Figure 4: Photographs showing examples of species found in Brazil
\nFigure 4: Photographs showing examples of species found in Brazil
\nWith reference to the images in the resource booklet, Figure 4, justify your choice of one animal as the most suitable to promote conservation.
\nan ideal flagship species (has a wide appeal to the public);
conserving this species will (result in habitat protection that will) also protect other species;
eg Golden tamarin:
potential attraction for eco-tourism;
as a primate it is closely related to humans/easy for humans to empathize with;
it has a human-like face / it is cute/cuddly/aesthetically attractive;
not found anywhere else / unique to Brazil (unlike other three species);
highly suitable for publicity/fund raising (eg posters/soft toys);
eg Brazilian merganser:
is critically endangered (most under threat and therefore needs conservation measures more quickly than the other organisms);
may attract many tourists/bird watchers/ornithologists;
appearance may be considered aesthetically attractive;
eg Broad-snouted caiman:
potential attraction for eco-tourism;
it is a predator and its loss could negatively impact other/keystone species;
eg Giant metallic ceiba borer:
may be a keystone species / its loss could impact on other species;
IUCN Red List status has not been assessed and therefore we should be cautious and ensure that it is not lost;
it is shiny which could be considered aesthetically attractive;
Award [0] if any plant species is used, or if an animal not listed above is used as an example.
Accept any reasonable responses.
[2 max]
\nMost candidates performed reasonably well on this question achieving one or two marks. The most popular answer was Golden tamarin as they are aesthetically attractive or cute. Candidates that chose an alternative animal often struggled to provide a second reason. Unfortunately, a large number of candidates selected a plant and hence were awarded no marks.
\nThe resource booklet provides information on Brazil. Use the resource booklet and your own studies to answer the following.
\nFigure 5(a): Fact file on population
\n[Sources: www.wwf.org.uk and www.survivalinternational.org]
\nUsing data from Figure 5(a) in the resource booklet, calculate the natural increase rate for Brazil in 2015.
\nIdentify one reason why the natural increase rate, calculated in part (a), is different from the actual growth rate of the population, which was 0.63% in 2015.
\n(natural increase = ) = 0.788%/ 0.79% / 0.8%;
\n7.88 per thousand.
\nCorrect units (% or per thousand) are required to be credited the mark.
\n[1 max]
\nmigration/emigration
\n[1]
\nMany candidates struggled to calculate the natural increase rate (NIR) correctly. Some candidates failed to apply the correct units. There were a significant number of candidates that did not attempt either of the calculation questions in this paper.
\nMany candidates were unable to identify migration as a factor that affected NIR. Many responses incorrectly suggested that the NIR did not take into account the crude birth rate, death rate or indigenous tribes. Some candidates did not appear to make the connection that the question was asking why the actual NIR was lower than the calculated rate in Q5a.
\nFigure 5(b): Age-gender pyramid for Brazil, 2014
\nFrom the shape of the age-gender pyramid in the resource booklet, Figure 5(b), suggest how the population in Brazil is likely to change in the next 30 years.
\ninitially the population will continue to grow rapidly;
…because there are still a significant number entering child-bearing age;
however, because the base of pyramid is decreasing/there are fewer children;
…this suggests fewer will be entering fertile bracket in future;
…lower birth rate;
…which will lead to slower growth rate;
…fertility rates may fall below replacement levels / reduction in fertility rates;
increasing proportion of higher age / in future an aging population (over 65 years old);
…the average age of the population will increase / higher median age of population;
…will lead to a larger senior dependency ratio;
a greater number of people in working age group (16–65 years old);
…compared to children (0–16 years old) will improve dependency ratio;
Brazil is at stage 3 and is moving to stage 4;
…will lead to a more stable population / equal proportion in each age group / birth rates
are equal to death rates.
Accept any other reasonable suggestions.
\n[3 max]
\nMost candidates achieved some marks for this question, with many achieving full marks. A common error was only to describe the illustrated age-gender pyramid and not suggest how it may change in the next 30 years. Many recognised that over the years it would become an aging population with a decrease in birth rate. Few students recognised that Brazil is currently at stage 3 and moving to stage 4 of the demographic transition model or that the growth rate would decrease, although the overall population would initially continue to rise.
\nFigure 4: Photographs showing examples of species found in Brazil
\nWith reference to the species listed in the resource booklet, Figure 4, identify two factors that may have contributed to their status given on the IUCN Red List.
\nreduction in population size;
population size / numbers of mature individuals / number of individuals able to reproduce;
geographical range / area of occupancy (ie where species are normally found) / extent of occurrence (boundary line that can be drawn around sites that the species occupies);
reduction in number of locations (the species is found in);
degree of fragmentation (eg via road or urban development);
quality of habitat / loss of habitat / habitat degradation;
probability/high risk of extinction.
Do not accept “availability of food/water/shelter”.
Do not accept “deforestation/hunting/low reproductive potential/habitat threatened” unless a link is made to the IUCN factors, as listed above.
[2 max]
\nIn general candidates did not answer this question well. The majority were unable to link the threats they gave to the IUCN Red List criteria e.g. how deforestation is linked to habitat loss and increase fragmentation of the habitat; or how hunting can result in a reduction in population size and change in the geographical range of the species.
\nFigure 9(a): Area used for bioethanol production and quantity of
bioethanol produced between 1990 and 2014
Figure 9(b): Biofuel production versus food production
\nFigures 9(a) and 9(b) in the resource booklet provide information about the production of ethanol from sugar as a biofuel.
\nExplain how biofuel production can be used as a strategy to control greenhouse gas emissions in Brazil.
\nFigures 9(a) and 9(b) in the resource booklet provide information about the production of ethanol from sugar as a biofuel.
\nOutline one limitation for using biofuels as a strategy to control greenhouse gas emissions.
\nbiofuel crops can be used to absorb carbon dioxide;
biofuels produce less greenhouse gases (when burnt) compared to fossil fuels/oil/petrol/gas;
use of biofuels is carbon neutral / carbon dioxide released during combustion is equal to the amount of carbon dioxide absorbed during plant growth (stage of biofuel production);
due to efficiency of biofuel production, further land clearance is not required, potentially protecting carbon sinks/forests;
production of biofuels may release less emissions than extraction and production of fossil fuels;
use of biofuels can reduce/replace use of fossil fuel (a non-renewable resource) / biofuels can replace use of fossil fuels in vehicles;
it can reduce the amount of carbon dioxide entering the atmosphere from storage.
[4 max]
\nproducing biofuels can conflict with production of sufficient food supply (for growing population) / reduce land used for food production / can reduce food production/availability of food;
…leading to more food being imported / this can elevate cost of food, (particularly impacting on the poor) / cause food shortages / it could lead to famine;
production of biofuels can use limited resources eg water for irrigation;
…this can result in water shortages/insufficient water for other uses;
adoption of intensification of farming practices can lead to greater use of fertilizers and pesticide;
…this can result in greater pollution of the environment eg nutrient run-off can cause eutrophication / use of pesticides can cause death of non-target species;
increasing amounts of land are required for growing biofuel crops;
…this can result in loss of habitats for native species/loss of biodiversity/land clearance can lead to soil degradation;
biofuels can be expensive;
…therefore less likely to be used;
growing crops for biofuels usually involves monocultures that reduces diversity;
…monoculture system is less resilient / high risk of crop failure.
Only one limitation should be credited.
For [2] the limitation and its impact must be explained.
Do not accept that burning biofuels still releases carbon dioxide as net increase compared to use of fossil fuel is still reduced.
Accept any other reasonable suggestions.
[2 max]
\nMany candidates focused on biofuel replacing the use of fossil fuels and how it produced less pollution than gasoline and therefore achieved 2 marks. Common errors included: (i) suggesting that when biofuels are used they do not produce any greenhouse gases; (ii) stating that biofuels produced less GHGs without reference or comparison to fossil fuels; (iii) discussing the disadvantages of using biofuels even though the command term was ‘explain’ and not ‘evaluate’. Few candidates recognised that carbon dioxide is absorbed by the crops used to make fossil fuels or that its use could be considered carbon neutral.
\nThe majority of candidates achieved at least one mark, with some good responses scoring 2 marks for this question. Common errors included stating two limitations (rather than the one specified) or not outlining the impact of the limitation given (e.g. a reduction in food production could lead to food shortage, famine or increase in food cost).
\nFigure 11(a): Ecological footprint and biocapacity of Brazil
\n(Biocapacity can be defined as the amount of biologically productive land, measured in total hectares per capita.)
\n[Source: © 2017 Global Footprint Network National Footprint Accounts from http://data.footprintnetwork.org]
\nWith reference to Figure 11(a), suggest what conclusions can be drawn regarding the sustainability of the Brazilian population over the period shown.
\necological footprint increasing over period suggests they are moving toward unsustainability;
biocapacity decreasing over period suggests they are moving toward unsustainability / Brazil is living unsustainably (using resources at a rate that is not replenishable) resulting in a decline in the biocapacity / if the line for biocapacity and ecological footprint meet/crossover it suggests unsustainability;
rate of decrease in biocapacity is falling/stabilizing toward end of period suggests they may remain/be moving towards being sustainable;
the Brazilian population/government will need to reduce their ecological footprint to sustain biocapacity;
ecological footprint being lower than biocapacity suggests population is sustainable.
Do not accept only “current ecological footprint is unsustainable”.
Do not accept “steady ecological footprint is sustainable”, as a stable ecological footprint is not necessarily a sign of sustainability.
To be credited the mark the response must link to sustainability.
[2 max]
\nThere were very mixed responses to this question. Many candidates outlined the change in the biocapacity and ecological footprint over time but did not relate this correctly to a reduction in sustainability. Some candidates misinterpreted the graphs and suggested that a decrease in biocapacity showed that land was being better cared for or that the rise in the ecological footprint showed that the population was living more sustainably.
\nThe concentration of DDT at different trophic levels of the food chain.
\nFigure 1: Levels of concentration of DDT in food chain
\n[Source: © International Baccalaureate Organization, 2017]
\nState the main source of energy for the food chain in Figure 1.
\nState the trophic level labelled X in Figure 1.
\nIdentify one use of DDT that has led to its presence in the environment.
\nWith reference to the concepts of bioaccumulation and biomagnification, outline how the concentration of DDT has changed along the food chain.
\nState the relationship between large and small fish in Figure 1.
\n\n
Outline how this relationship may be of benefit to the populations of both species.
\nSun/sunlight/insolation/solar energy
\n(primary) producer / autotrophs / phototrophs / phytoplankton / green plants
\nThe command term “State” requires a “specific name” so do not credit “trophic level 1”.
\n\n
insecticide/pesticide / kill pests/insects / control malarial mosquitoes / plague / OWTTE
\n\n
\n
bioaccumulation: DDT absorbed by a given trophic level is not broken down/excreted / is non-biodegradable so accumulates in tissues [1 mark]
\nbiomagnification: the concentration of DDT will increase as it’s passed along/up food chain (because other biomass is lost) [1 mark]
\nDo not allow simply “organisms at higher levels eat/consume more”. Higher trophic levels do not consume more biomass in a given time than lower trophic levels.
\n\n
predator-prey / carnivory / predation / OWTTE
\nDo not credit “small fish are eaten/consumed by large fish”.
\n\n
\n
the predator benefits by gaining food from prey / its population is limited/stabilized by amount of prey available [1 mark]
they prey benefits by predators limiting/stabilizing its population / selecting out weaker/diseased individuals / maintaining healthy gene pool in prey / reducing competition in prey for available food/resources [1 mark]
Award full marks is response describes negative feedback between both populations, or indicates that each group regulates population of the other.
\n\n
Only around half the candidates were able to identify solar energy as the energy source for food chains.
\nGreat majority were able to identify plants/primary producers as base of food chain.
\nMost were able to identify DDT as a pesticide … students should be advised that where question specifies a single response it is not a wise strategy to offer a selection of responses.
\nVery few candidates were able to apply these terms of “bioaccumulation” & “biomagnification” appropriately …some confused the two; some made no reference to them as required by the question. More were able to identify biomagnification correctly than bioaccumulation.
\nMost were able to identify predation but a surprisingly large number failed to do so.
\n\n
The great majority were able to identify benefits to both populations.
\nWater stress is the total annual extraction of water as a proportion of the renewable supply in a given area. If the extraction represents 40 % or more of the available supply it is described as a high risk area.
\nFigure 2: Water stress for selected crops
\n[Source: World Resources Institute,
http://www.wri.org/resources/charts-graphs/portion-agricultural-production-under-high-or-extremely-high-stress.
Used with permission.]
State the crop that is under the greatest water stress.
\nIdentify two strategies that could be used to grow crops in areas of high water stress.
\nIdentify three factors that may lead to an increase in water stress.
\ncotton
\nimproved irrigation efficiency eg drip irrigation;
use crop cultivars that require less water (eg drought resistant seeds/GMOs) / replace high stress crops (eg cotton) with low stress (eg oats);
improve water catchment/storage with dams; reservoirs;
install desalinization plants in coastal areas;
plant cover crops/use terracing (to reduce evaporation/run-off losses);
use salt-tolerant crops to exploit available sea-water/saline soils.
Do not credit simply “irrigation”. Too vague.
\n\n
increased demand through increased population / domestic/agricultural/industrial use;
increased water consumption through more affluent lifestyles / shift to meat-rich diets;
move towards more intensive agriculture/irrigation / unsustainable abstraction of water;
movement of water out of drainage basin eg aqueducts / upstream use by other countries;
growing of inappropriate/heavily water-dependent crops;
deforestation in drainage basin / pollution/contamination of water sources;
drought/reduction of rainfall (due to global warming/El Niño).
Award [1] for each correct factor identified, up to [3 max].
For last MP, do not accept simply a description of a regular climate eg low rainfall/dry season. The question asks for what will increase stress, so there needs to be a suggestion of change.
Marking points above may be stated as given or explicitly demonstrated through reference to examples/case studies (eg cotton around Aral Sea absorbs excessive water from an environment at risk).
\n
The vast majority correctly associated cotton with highest water stress.
\nMajority of candidates could identify at least one appropriate strategy …incorrect responses were generally due to being too vague or inaccurate e.g. ‘better irrigation’; ‘crop rotation’.
\nMost candidates could come up with a couple of valid causes of water stress …incorrect answers again were often too vague e.g. ‘growing lots of crops’ and a significant number mistook water stress for flooding.
\nThe soil system includes storages of inorganic nutrients.
\nIdentify two inputs to these storages.
\nThe soil system includes storages of inorganic nutrients.
\nIdentify two outputs from these storages.
\nSolid domestic waste may contain non-biodegradable material and toxins that have the potential to reduce the fertility of soils.
\nExplain how strategies for the management of this waste may help to preserve soil fertility.
\nThe provision of food resources and assimilation of wastes are two key factors of the environment that determine its carrying capacity for a given species.
\nTo what extent does the human production of food and waste each influence the carrying capacity for human populations?
\nInputs:
\nCandidates may present their answers in the form of a diagram, but it is not necessary for full credit.
Award [1] for each correct input identified, up to [2 max].
Do not credit flows that are transfers or transformations within the soil eg ammonification / nitrification / capillary movement, etc.
Do not accept “pesticides” (these do not provide inorganic nutrients).
Outputs:
\nCandidates may present their answers in the form of a diagram, but it is not necessary for full credit.
Award [1] for each correct output identified, up to [2 max].
Do not credit flows that are transfers or transformations within the soil eg ammonification / nitrification / capillary movement, etc.
recycling/re-use helps by preventing the release of non-biodegradable material/toxins into the soil;
reduction helps by reducing the quantity of non-biodegradable material/toxins produced/manufactured;
promoting selective consumerism to avoid toxic products prevents them being present in domestic waste;
education/laws/fines that promote disposal of hazardous domestic waste in appropriate collecting facility will reduce their impact on soil fertility;
incineration may be helpful in breaking down non-biodegradable substances/organic toxins;
…and the remaining mineral content can be used to enhance soil fertility;
landfills can limit the release of non-biodegradable material/toxins into soil with effective lining;
sorting of waste before entry to landfill can remove many toxic substances eg batteries/fluorescent lamps/tyres/spray cans reducing risk to soil fertility through leakage;
deep well injection of hazardous wastes will prevent soil toxification;
all strategies that prevent release of toxins will preserve the soil fauna that contribute to fertility;
composting (although it does not breakdown non-biodegradable material/toxins) can compensate to some extent by providing soil nutrients that improve soil fertility.
Award [1] for each correct explanation, up to [7 max].
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nQuestion 6 was a quite popular choice. Part (a) very rarely scored full credit with a lot of responses going for non-mineral inputs and outputs (e.g. water, sun, CO2 etc).
\nQuestion 6 was a quite popular choice. Part (a) very rarely scored full credit with a lot of responses going for non-mineral inputs and outputs (e.g. water, sun, CO2 etc).
\nMost candidates were able to name a few relevant strategies for managing solid domestic waste. However, credit was generally less than maximum because responses focused on evaluating the strategies (particularly their weaknesses), which was not required by the question. Responses would have scored more by identifying further modifications or other strategies.
\nA significant proportion of responses identified the fundamental relationship between food/waste production and carrying capacity …but then did not go far beyond this in exploring how these are influenced by agricultural techniques/management strategies/geographical and social factors and so on.
\nThere are concerns that increased carbon dioxide (CO2) emissions are leading to changes in the global climate.
\nFigure 3: CO2 emissions for select countries in 2007 and 2030 (Projected)
\n[Source: World Resources Institute,
http://www.wri.org/resources/charts-graphs/capita-co2-emissions-select-major-emitters-2007-and-2030-projected.
Used with permission.]
\n
Calculate the projected percentage increase from 2007 to 2030 in CO2 emissions for Russia.
\nOutline how CO2 emissions may cause a change in the global climate.
\nIdentify two possible reasons for the projected change in CO2 emissions for China.
\nIdentify one reduction strategy that the United States might use to achieve its projected change in CO2 emissions.
\nIdentify one adaptation strategy that could be used to reduce the impacts of climate change.
\nExplain how the ability to implement mitigation and adaptation strategies may vary from one country to another.
\n= 34% increase (allow 32−36%).
\n\n
\n
emissions (lead to higher concentration) of CO2 which is a greenhouse gas;
…causing greater absorption of infra-red/heat radiation and rise in global temperature;
…leading to increased evaporation/changing winds/shifting patterns of precipitation/droughts/extreme weather events/storms/hurricanes/El Niño.
\n
growing number of fossil-fuelled vehicles/transport;
rapidly advancing economy/standard of living;
increase in fossil-fuelled power plants / increased industrialization;
increase in intensive/mechanized farming systems (in place of traditional);
burning of forests to clear land for agriculture.
Accept any other reasonable suggestions.
Award [1] for each correct reason identified, up to [2 max].
\n
reduction of energy consumption/CO2 production through laws/taxes/education;
use of alternatives to fossil fuels;
CO2 removal though CCS;
afforestation / reducing rates of deforestation.
Accept any other reasonable suggestions, but they must be explicitly linked to reduction in C emissions ie not simply “improve public transport” or “recycling”.
\n\n
flood defences (ie levees/dikes);
desalinization plants to replace freshwater losses;
planting of crops in previously unsuitable areas;
water conservation (eg restrictions on use of irrigation/sprinklers);
exploiting areas that have become more productive for crops through climate change;
developing (eg drought-resistant) crops better adapted to areas impacted by climate change;
green roof system that cools the building through evapotranspiration/reflection.
Accept any other reasonable suggestions.
Some strategies can be acknowledged as both adaptive and mitigating eg a “green roof” both reduces impact of climate change by cooling the building (adaptation) and reduces cause of climate change by reducing C emission (mitigation). Such suggestions should not be credited unless the link to reducing impact is made clear.
\n
political will/pressure for change may differ due to some countries being more/less committed to their industrial lifestyles/economic growth / inhibited through political corruption;
finance/economics may/may not allow some countries to fund new technologies/infrastructures;
some countries may depend upon others for knowledge transfer/technological assistance to implement resolutions;
religious/political/cultural norms/education in some countries may promote/limit their perception of environmental threats/approach to management;
geographical location of some countries may place them at greater/more immediate risk from impacts of climate change (eg low-lying islands/tropical storm-prone nations) / or offer them greater opportunities for mitigation (eg available sources of alternative energy);
some countries may perceive greater immediate priorities eg war in Syria/poverty in Somalia.
Award [1] for each correct explanation, up to [4 max].
Accept other valid explanations of equivalent validity.
Do not accept eg “Economics” alone without an explanatory note.
\n
The majority of candidates were unable to calculate a % increase.
\nMost could identify CO2 as a greenhouse gas …but a surprisingly large proportion associated its impact incorrectly with the ozone layer/depletion and UV radiation.
\nA considerable majority correctly identified changes shown in the data and offered valid explanations.
\nA considerable majority correctly identified changes shown in the data and offered valid explanations.
\nOnly a minority of candidates could offer an example of adaptation strategies.
\nMost candidates identified one valid reason for differences between countries …incorrect answers were again too vague, e.g. ‘economics’; ‘politics’ …there needed to be at least a degree more explanation. Responses tended to focus on economic/technological differences rather than the geographical and cultural.
\nFigure 2(b): Examples of ecosystems in London
\n[Source: (top left) O’Connor, P., 2015. GOC Walthamstow to Stratford 164: Old English Garden, Victoria Park. [image
online] Available at: https://www.flickr.com/photos/anemoneprojectors/25609419345/in/photostream/ Attribution-
ShareAlike 2.0 Generic (CC BY-SA 2.0) https://creativecommons.org/licenses/by-sa/2.0/ [Accessed 22 May
2020]. Source adapted.
(top right) Taylor, J., 2009. Park Crescent, London NW1 private communal garden. [image online] Available at:
https://fr.m.wikipedia.org/wiki/Fichier:Park_Crescent,_London_NW1_private_communal_garden_-_geograph.org.
uk_-_1268358.jpg Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) https://creativecommons.org/licenses/bysa/
2.0/ [Accessed 22 May 2020]. Source adapted.
(bottom left) Haywood, Jay., 2004. Grey Heron in London Wetlands Centre. [image online] Available at:
https://commons.wikimedia.org/wiki/File:Grey_Heron_in_London_Wetlands_Centre_-_geograph.org.uk_-
_795424.jpg Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) https://creativecommons.org/licenses/by-sa/2.0/ [Accessed 22 May 2020]. Source adapted.
(center left and right) Oberst, T., 2019 Untitled. [photograph].]
Figure 3: Climate graph for London
\nFigure 4(a): Green spaces in London
\n[Source: Greater London Authority, 2016. Draft Economic Evidence Base 2016. [online] Available at: https://www.london.
gov.uk/sites/default/files/draft-eeb-2016.pdf [Accessed 1 June 2020].]
With reference to Figures 2(b) and 3, identify an ecosystem found in London.
\nOutline one factor which limits the primary productivity of an ecosystem in London.
\nIdentify one distribution pattern of green spaces seen in Figure 4(a).
\nOutline three ways that London’s green spaces are considered natural capital.
\ngrassland/meadow /marshland/wetland/ pond/lake/ river / urban/ (temperate/deciduous/temperate deciduous) forest / woodland / garden / (city) park/parkland;
\nNote: Do not accept only ‘terrestrial/freshwater ecosystem’.
\ncold temperatures in the winter months (4 °C in January) could inhibit photosynthesis/plant growth;
seasons/limited insolation in the winter could reduce photosynthesis/plant growth;
air pollution limits photosynthesis/plant growth;
Notes: Do not credit ‘limits variety of vegetation/lowers primary productivity’.
For credit, response must link to photosynthesis/plant growth, not just productivity.
Do not credit ‘low precipitation/rainfall’.
Notes: For credit response must relate to the distribution of green spaces.
Do not accept ‘uneven / found in the South’.
The majority of candidates correctly identified an ecosystem found in London.
\nVery few candidates answered this question correctly. Many candidates did not consider the command term used and stated a correct factor eg low temperature or sunlight but did not relate this to its effect on photosynthesis and therefore primary productivity. A few responses incorrectly suggested that high levels of rainfall caused flooding.
\nMost students answered this question well with many responses referring to the green spaces found on the edges of the city.
\nResponses varied widely for this question with most candidates achieving at least one mark. A common error was to repeat statements from Figure 4(b) rather than use this information to consider the goods and services gained from London’s green spaces.
\nFigure 8: Area used for grain production and quantity of grain produced between 1990 and 2014
\nDescribe the relationship between harvested area and grain production as shown in the resource booklet, Figure 8.
\nWith reference to Figure 8, outline two reasons for the relationship between the area used for grain production and the quantity of grain produced.
\nthe amount of grain production has significantly increased over time / the amount of grain produced has increased almost 4-fold / from about 50 million tonnes to about 200 million tonnes over 24 years;
whereas the amount of land used to grow grain has only increased slightly/from about 30 million hectares to about 50 million hectares;
the increase in land used is not proportional to the increase in grain production / grain production is independent to harvested area / there is no relationship between grain production and land harvested / grain production has increased more rapidly than harvested area;
there is a (slight/small) positive relationship/correlation between the amount of land used and amount of grain produced / crop production increases (to some extent) with the amount of land used.
If quantification is used the units should be correct, ie either in thousand thousand/million hectares/tonnes.
\n[2 max]
\nintensification of farming methods/technological improvements that does not increase amount of land used to grow more crops / more efficient land use leads to increase in crop production;
increase in use of fertilizers to increase crop production;
increase in irrigation to increase crop production;
use of pesticides to reduce crop losses to pests or reduce competition;
growing pest resistant plants resulting in higher yields;
use of crop varieties (genetically modified organisms GMOs) that produce high yields / high yielding varieties HYV;
use of crops that grow more quickly allowing multiple harvests;
increase in mechanization allowing greater speed of planting/harvesting crops reducing crop losses;
increase in number of times crops are planted in a year.
Do not accept “more land available, the more grain can be produced” as it does not address the large increase in crop production.
Method must relate to increase in crop production.
Accept any other reasonable suggestions.
[2 max]
\nMost candidates scored at least 1 mark on this question although some responses lacked the necessary detail or did not include the correct units as specified on the y-axis in Figure 8.
\nMany candidates were unable to explain why the level of grain production had significantly increased with only a relatively small increase in the amount of land used and simply suggested that the increase in production was due to an increase in land used. Those that gave a correct response often referred to improvements in technology or use of fertilizers that have allowed grain production levels to increase without increasing the amount of land used. Some candidates did not link ‘cause’ with ‘effect’ i.e. they stated ‘use of fertilizers’ without linking it to an increase in grain production.
\nIdentify four ways in which solar energy reaching vegetation may be lost from an ecosystem before it contributes to the biomass of herbivores.
\nSuggest a series of procedures that could be used to estimate the net productivity of an insect population in kg m–2 yr–1.
\nTo what extent are the concepts of net productivity and natural income useful in managing the sustainable harvesting of named resources from natural ecosystems?
\nreflected from the leaf surface;
absorbed by non-photosynthetic surface;
heat/some wavelengths are absorbed by leaf but not used in photosynthesis/not converted into chemical energy;
(chemical energy/GPP) respired by vegetation;
(chemical energy/GPP) not eaten/harvested by consumer / dead material consumed by decomposers;
eaten but not absorbed by herbivore / lost in faeces;
absorbed by herbivore, but lost through respiration.
Award [1] for each correct way identified, up to [4 max].
\n\n
measure change in population size over year;
using Lincoln Index/mark-release-recapture;
set traps/capture a sample, mark and release them;
re-set traps for a second capture and calculate the proportion marked and unmarked;
use the equation:
\nweigh a sample of insects to find (wet) weight;
use a conversion factor to calculate dry weight from (wet) weight;
calculate mean dry weight/biomass per individual;
from mean dry weights and population sizes calculate total weight change over year;
estimate area occupied by population using measuring tapes/scale maps;
divide total change in dry mass by area in m2;
Award [1] for each correct suggestion, up to [7 max].
Credit any alternative sequence of procedures that is equally appropriate to finding net secondary productivity eg using lab population and weighing dry weight of food, faeces, respiration rates, etc, awarding marks similarly to scheme above.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nQuestion 4 was the least popular question and generated very few good responses. Most candidates focused on energy losses in the atmosphere before reaching the vegetation …which was not addressed by the question.
\nA good proportion of candidates gained some credit for describing a protocol to estimate population size, but few could go on to find productivity.
\nMost could link net productivity and natural income with sustainable harvesting …although some confused natural income with financial gain. Very few were able to evaluate this in different contexts however, particularly so in regard to the weakness in these quantities/models.
\nIdentify four characteristics of ecosystems that contribute to their resilience.
\nExplain how positive feedback mechanisms may influence the equilibrium of an aquatic ecosystem during the process of eutrophication.
\nPollution management strategies may be aimed at either preventing the production of pollutants or limiting their release into ecosystems.
\nWith reference to either acid deposition or eutrophication, evaluate the relative efficiency of these two approaches to management.
\nbiodiversity (genetic/species/habitat diversity);
diversity/complexity of interactions/linkages between components/developed food webs/nutrient cycling/establishment of keystone species;
size of storages/population sizes / abundance of resources;
presence of negative feedback mechanisms;
position of tipping points/thresholds of change;
maturity/later stage of succession/climax community;
balance of inputs and outputs / steady state equilibrium.
Award [1] for each correct characteristic identified, up to [4 max].
Do not accept responses that simply state “storages” or “tipping points”, all systems have these. It is the size or position of the storage or tipping point respectively that determines its resilience. Simply stating “biodiversity”, however, is acceptable because it is inherently quantitative.
Do not accept responses referring to low human interference, etc. Reduced disturbance may lead to more stable ecosystems, but it does not influence their resilience as such (ie their inherent ability to resist disturbance).
\n
in eutrophication, positive feedback amplifies changes in the system and drives it toward a tipping point;
…when a new equilibrium is adopted with low diversity/loss of species/dominance of algae;
Award [5 max] for marking points given above (including each of those in a box on the diagram) or up to [7 max] if the processes identified complete a genuine loop of positive feedback ie where a given change promotes further change of same process.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nFor Eutrophication:
\nFor Acid Deposition:
\nIf response addresses both acid rain and eutrophication, only award marks for the higher scoring topic.
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nQuestion 5 was a popular choice. The majority could identify biodiversity as a factor contributing to resilience; other factors were less commonly listed or too vague/confused to gain credit.
\nA very significant majority were able to gain over half the available marks through a description of eutrophication. Few were able to demonstrate a complete and valid positive feedback loop, commonly seeing it as just an ongoing process with lots of impacts (no feedback).
\nResponses were very generally quite poor with the vaguest of strategies, e.g. ‘banning the pollutant’; ‘limiting the use of the pollutant’. Also, many responses failed to make a clear/valid distinction between preventative and limiting strategies.
\nFigure 5: Fact file on deer species found in London
\n[Source: Nilfanion, 2010. Muntjac deer at Dumbleton Hall. [image online] Available at:
https://fr.wikipedia.org/wiki/Fichier:Muntjac_deer_at_Dumbleton_Hall.jpg Attribution-ShareAlike 3.0 Unported (CC
BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.en [Accessed 22 May 2020]. Source adapted.
Lviatour, 2011. Cervus elaphus Luc Viatour 6. [image online] Available at:
https://commons.wikimedia.org/wiki/File:Cervus_elaphus_Luc_Viatour_6.jpg Attribution-ShareAlike 3.0 Unported
(CC BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.en [Accessed 22 May 2020]. Source
adapted.
Manfred Antranias Zimmer /Pixabay.com, 2018. Striking Fallow Deer Buck, boasting an impressive rack. [online]
Available at: https://pixabay.com/photos/antler-fallow-deer-deer-dama-dama-899123/ [Accessed 13 September
2021].]
Figure 6(a): Population of deer in Richmond Park, 2013–2017
\nFigure 6(b): Number of deer removed from Richmond Park, 2013–2017
\nFigure 6(c): Fact file on Richmond Park
\nRichmond Park is a national nature reserve and Special Area of Conservation.
\n[Source: The Royal Parks, 2020. Deer in Richmond Park. [online] Available at: https://www.royalparks.org.uk/parks/
richmond-park/richmond-park-attractions/wildlife/deer-in-richmond-park [Accessed 1 September 2020].
Oberst, T., 2019. Untitled. [photograph].]
Using Figure 5, construct an identification key for the deer species found in London.
\nWith reference to Figures 6(a), 6(b) and 6(c), predict how the ecosystem would be affected if the deer population in Richmond Park was not managed.
\ncorrect identification of features [2 max] such as:
\nNotes: Do not accept questions relating to bigger/smaller or specific size of deer (which could be dependent on age of deer).
Do not credit suggestion that Reeves muntjac has no antlers.
Do not credit just ‘skin pattern/pattern on body’.
iv. correct format of key; [1 max]
\nNotes: Accept a dichotomous key with clear yes/no questions and two branches from each question, leading to the correct deer at each end point or clear question statements with “go-to” links.
Mark can be achieved for correct format of key even if inappropriate identification features are chosen.
Note: Do not accept only ‘causes instability / causes positive feedback / causes ecosystem to collapse / causes land degradation / competition for food / food hard to get / resources are depleted’.
\nMost candidates struggled with this question with very few achieving the maximum three marks. Many responses incorrectly used size (of body or antlers), location, breeding rates or diet to differentiate between the deer. A significant number of candidates that did not attempt this question.
\nMany candidates answered this question well with most recognising that the population of deer would increase resulting in overpopulation. Many responses then connected this to overgrazing. Some responses were too vague stating ‘instability’ or ‘collapse of the ecosystem’ without indication of the actual changes or why.
\nFigure 8(a): Fact file on urban agriculture and vertical farms
\nVertical farms:
\nUrban beekeeping:
\nFigure 8(b): Underground vertical farm
\n[Source: LouisHiemstra / www.istockphoto.com.]
\nFigure 8(c): Rooftop beekeeping
\n[Source: Permission from Berkeley Homes.]
\nState one strength and one weakness of using the ecological footprint as a model for measuring sustainability.
\nState one factor that would allow a region’s ecological footprint to exceed its biocapacity.
\nWith reference to Figures 8(a), 8(b) and 8(c), suggest how urban agriculture could be used to increase the carrying capacity of London.
\nStrengths of model: [1 max]
\nNotes: Do not accept only ‘it is inaccurate / does not use outliers’.
Do not accept ‘does not account for changes over time’.
importing resources/food;
exporting waste products;
Notes: Do not accept only ‘bees increase resources available’ without reference to increasing food.
Do not accept ‘bees provide healthier food’.
Do not accept only ‘no pesticides used / provides goods / produces agricultural items / pesticides cause eutrophication’.
Many students attempted to give a definition of an ecological footprint or sustainability rather than focusing on a strength and a weakness of using a model in determining EF.
\nFew candidates answered this question correctly. This question was misinterpreted by most students and many responses incorrectly focused on using more local resources.
\nMost candidates achieved some marks for this question with many recognising that vertical farming uses less water, less land area and increases availability of food. Few candidates linked beekeeping to pollination and primary productivity. Some students confused the use of pesticides with fertilizers, incorrectly suggesting pesticides cause eutrophication. There was a significant number of candidates that did not attempt this question.
\nFigure 9: Annual mean oxides of nitrogen (NOx) concentrations measured in London air, 2016
\n\n
[Source: Greater London Authority (GLA) https://data.london.gov.uk/dataset/london-atmospheric-emissions-inventory--
laei--2016.]
With reference to Figure 9, explain why the highest levels of NOx are found in the centre of London.
\nEvaluate one strategy to reduce NOx emissions from transport.
\nIdentify two potential impacts of improved air quality on London and its population.
\nNotes: Figure 2a states electricity is generated outside the city.
Do not accept there are more industry/factories in central London that generate NOx.
Do not accept only ‘there are few green spaces/trees’, link needs to be made to trapping air pollutants/cleaning the air.
Examples of strategies include (N.B. no marks for stating strategy): use of congestion charges/higher tax for using cars, increase/shift to hybrid/electric cars, use of catalytic converters, increase public transportation / increase bicycles/free bicycle scheme, carpooling, shift to cleaner fuel sources for public transportation, stricter emissions controls on car exhaust, shift to solar powered cars/vehicles.
\nConclusion [1 max] needs to consider both sides of the argument for credit. For Example 1, above, “while higher taxes may decrease the number of cars entering the city, this simply moves the problem into other zones around the centre, and therefore it is not an effective strategy.”
\nNotes: Conclusion is not mandatory and [3] marks can be achieved through consideration of both advantages and disadvantages.
Do not award a mark for stating only strategy.
Accept other reasonable responses.
Notes: Doesn’t need to be one impact for London and one for population.
Do not credit only ‘improved health/reduction in diseases / reduction in photochemical smog / affects plants / better vegetation’.
Do not credit ‘less pollution would lead to greater tourism and increased revenues’.
Most candidates achieved at least one mark here for recognising that the high density of transportation in London contributed to the higher levels of NOx. Many responses only provided one or two reasons rather than the three required to achieve the three marks for this question.
\nMost students were able to give an appropriate strategy but in a significant number of responses there was no evaluation.
\nThere were some very good responses to this question with many candidates achieving full marks. Common error was to give vague responses e.g. improves health or reduces disease.
\nThe resource booklet provides information on the Swakop River Valley. Use the resource booklet and your own studies to answer the following.
\nFigure 1(b): Map showing Swakop River in Namibia
\nFigure 4(b): Investigation into the impact of Mesquite on mammals in the Swakop River Valley
\nThe data in the table show the number species captured by camera shots, in two areas of different
mesquite densities, over 100 days.
Figure 5(a): Graph to show Uranium prices from 1980 to 2013
\nFigure 6(a): Strategic Environmental Management Plan (SEMP) for the Swakop Valley
\nFigure 7: Erongo water desalination plant
\n[Source: Adapted from http://www.world-nuclear-news.org/C-Areva_water_plant_to_supply_Namibian_mines-1908134.html]
\nState the biome for the area shown in Figure 1(b).
\nIdentify three natural sources of water available in the Swakop area.
\nOutline two reasons why the Swakop river is considered to be ecologically important.
\nOutline whether an invasive species such as Mesquite is likely to be r-strategist or K-strategist.
\nWith reference to the data in Figure 4(b), suggest two conclusions which can be drawn from the camera trap data.
\nJustify whether or not Mesquite should be cleared from the Swakop River Valley.
\nWith reference to Figure 5(a) describe how Uranium prices have changed over time.
\nOutline two reasons why the value of resources like Uranium can change over time.
\nWith reference to Figure 6(a) describe two ways in which Uranium mines have had an impact on water resources.
\nWith reference to Figures 6(a) and 7, calculate the amount of water available for other uses, after the Erongo desalination plant has met the needs of the three operational mines.
\nUsing evidence from the resource booklet, justify from an ecocentric viewpoint why the Husab Uranium Project should not be approved.
\ndesert/savanna
\n[1]
\nThis question requires “Resource Booklet - Nov 2016 SL paper 2”, available under the \"your tests\" tab > supplemental materials.
\nSwakop river/river runoff/linear oasis;
groundwater/aquifers;
rainfall/precipitation;
condensation/dew/coastal fogs;
ocean.
3 correct award [2].
2 correct award [1].
1 correct award [0].
[2 max]
\nThis question requires “Resource Booklet - Nov 2016 SL paper 2”, available under the \"your tests\" tab > supplemental materials.
\nrange of habitats/passes though different ecosystems;
\nwater supply/linear oasis/corridor of water through the desert/lifeline for animals/buffer against drought;
\ncontains endemic species/higher biodiversity/unusual plants e.g. Welwitschia;
\nmouth important habitat/feeding ground for birdlife;
\ninteresting study site / place to study invasive species.
\n[2 max]
\nThis question requires “Resource Booklet - Nov 2016 SL paper 2”, available under the \"your tests\" tab > supplemental materials.
\nr-strategist because produces many offspring/many seeds/spreads quickly/grows rapidly.
\nAward [1] for r-strategist plus valid reason.
\n[1]
\nConclusion (Conc): some species increase whereas others decrease with density of mesquite;
Development (Dev): e.g. Oryx is more common in low mesquite areas but Baboons are less common;
Conc: number of species/species richness is same in high and low mesquite areas;
Dev: i.e. both areas have same number/12 species present;
Conc: species diversity is greater in low mesquite area;
Dev: the diversity index is about 5 in low and about 4 in high mesquite area;
Conc: some species are more common/more commonly photographed than others;
Dev: e.g. most were Steenboks (193 times) and least were Badgers (5 times);
Conc:: some species seem quite unaffected by mesquite;
Dev: e.g. steenboks/jackals have very similar numbers in both areas;
Conc: total no of organisms/activity appears to be higher in mesquite area;
Dev: ...because there are a total of 309 camera shots in high mesquite and only 267 in low / mesquite area may provide better habitat quality/more food/better shelter;
Conc: some species e.g. baboon/kudu/wildcat/klipspringer/porcupine do better in high mesquite;
Dev: perhaps because they feed on mesquite / their competitors are more negatively affected by mesquite;
Conc: some species e.g. Oryx/duiker/rodent do less well in high mesquite;
Dev: perhaps because mesquite replaces important source of food/shelter.
If development is given with no explicit conclusion, award 1 max for that example.
Credit any reasonable conclusions from the data for [1], with some development or exemplification for the second mark.
Accept other reasonable responses.
\n[4 max]
\nThis question requires “Resource Booklet - Nov 2016 SL paper 2”, available under the \"your tests\" tab > supplemental materials.
\nCandidates can argue either way:
for example: yes, it should be cleared because:
its negative effect on farms / outcompetes their crops;
it is invasive/spreads rapidly/is non-native displacing local species;
has changed the habitat significantly/research shows negative impact on vegetation, wildlife & birds;
due to aesthetic reasons;
it has a negative effect on water resources in an arid area;
For example: no it should not be cleared because:
it provides a renewable resource for humans;
e.g. firewood/food for humans;
local communities can earn an income from it;
Namibia is a poor country and so helps to address poverty / less than 1 % of thepotential income from Mesquite pods is currently being generated;
Some animals may have adapted to it/feed on it and would be negatively affected (e.g. baboon).
Accept other reasonable responses.
This is not a “discuss” question, so candidates should opt for one response only, and justifications should be credited for either clearing the mesquite or not clearing the mesquite.
[3 max]
\nprices decreased gradually from 1980 to 1985/1989;
\nremained fairly stable between 1985/1989 to 2005;
\nthere was a spike in prices between 2006 and 2008;
\nprices dropped between 2008–2010;
\nbut have remained higher than pre-2005.
\nWTTE / other figures if appropriate are acceptable.
\n[2 max]
\nvalue of resources change over time due to changing needs/shifting cultural values/technological development/accessibility;
\nas technology made it possible to use uranium for nuclear energy, demand (and price) of Uranium increases;
\nas countries seek alternatives to fossil fuels / more nuclear power stations opened so uranium increases in value;
\nadoption of ecocentric values e.g. Sweden, reduces demand for uranium so price falls;
\nconcern over nuclear accidents like Fukushima reduces demand for uranium so price falls;
\nmore mines opened/new deposits found so increase in supply reduces price;
\ndrop in global uranium extraction (due to political decision) may cause increase in price.
\nAccept other reasonable responses.
Credit responses referring to dynamic nature of resources, even if they use other resources as example.
[2 max]
\nuranium mines use huge amounts of water so deplete supplies/lead to over abstraction;
\nuranium mines contribute to pollution of water resources with radio-nuclides/wastes from mining;
\nwaste rock dumps can lead to diversion of water courses.
\n[2 max]
\n10 million cubic metres [per year]
\n[1]
\nThis question requires “Resource Booklet - Nov 2016 SL paper 2”, available under the \"your tests\" tab > supplemental materials.
\nHusab will negatively affect endemic species e.g. Welwitschia;
\nHusab will disturb natural processes e.g. pollute Swakop river/groundwater from radioactivity/waste rock dump;
\nimpacts of Husab will infringe biorights/degrade intrinsic value of species/ecosystems;
\ninstead of supplying more uranium we should be looking at more renewable energy alternatives;
\ncommunity involvement is important and this is unlikely with a large scale privately owned mine;
\nuranium is not a sustainable solution to energy needs as there is a finite amount of uranium;
\nwe should be reducing our use of resources (such as uranium and water) not increasing them;
\nonly 1.8 % of the population is employed in mining anyway so local communities are not benefiting much from the industry;
\nthe tourist value of the area is of greater significance in terms of employment than uranium mining.
\n[4 max]
\nOnly a very small minority gave an incorrect answer here, as long as they knew what a biome is; it was occasionally confused with ecosystem.
\nMost answers managed to gain one mark. The answers commonly confused man-made sources of water like “dams”, so some candidates did not meet the second mark.
\nThe candidates understood the concept of the question and most gained the 2 marks. But a minority did not gain credit since they described economic or social aspects instead of those that are ecologically significant.
\nMost candidates answered well, with a few exceptions that didn’t realize that ‘outline’ needs reasoning to obtain full marks, and just stated “r-strategist”.
\nThe candidates generally had no problems; nevertheless some candidates couldn’t read the diagram, so it was hard to get full marks since two conclusions were needed.
\nMost candidates managed 2 marks here, but some ability of written expression was needed to get the three marks.
\nMost candidates got the two marks.
\nThe candidates could often identify supply/demand principles to the value of a resource; nevertheless, some candidates forgot to link their reasoning to a specific change in value, making 2 max as a result.
\nSince there were two possible answers depletion and pollution of water resources, most candidates performed well, except for a few who were unable to state the cause of the water pollution.
\nMost candidates gained the full mark, with a small percentage unable to perform even the simplest mathematical calculations.
\nVery few candidates were able to get 4 marks, since no clear and explicit links to ecocentric viewpoints were made. Usually they could identify biorights and at times the pollution of groundwater, but not much further.
\nOutline one climatic and one edaphic (soil) factor which affect the final climax community in an ecosystem.
\nExplain two examples of soil degradation and the appropriate soil management strategies from a named farming system.
\nEvaluate the impact of economic development on the ecological footprint of a human population.
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nClimatic:
amount of precipitation / insolation / (mean) temperature;
limit primary productivity/rate of photosynthesis that will determine the available biomass/food base/on which climax community will depend;
Edaphic:
soil depth / mineral content/amount of N/P/K / soil compaction/aeration / soil particle size / balance between clay, silt and sand / percolation rate / soil pH;
determine the particular vegetation types/plant species adapted to those conditions that support the climax community.
Award up to [2 max] for climatic factor and up to [2 max] for edaphic factor.
\n[4 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nNamed farming system: e.g. intensive corn (Zea mais) farming in Mid-West of USA;
\nDegradation (Deg) + Strategy (Strat): soil compaction managed by addition of organicmatter/manure / reduced tillage;
\nDeg: compaction leads to reduced drainage/oxygen levels in soil which reduces ability of roots/crop to grow (and support crop);
Strat: organic matter enhances the soil ecosystem which helps aerate soil / reduced tillage allows soil ecosystem to recover and aerate soil;
Deg + Strat: toxification of soil managed by reduced use of inorganic fertilisers/pesticides / bioremediation;
\nDeg: excess use of liquid ammonia/fertilisers / pesticides can reduce range of soil microorganisms able to live;
Strat: reduced use of chemical additives allows soil ecosystem to recover and provide ecosystem service of nitrogen fixation;
Deg + Strat: acidification of soil managed by addition of lime;
\nDeg: acid precipitation in areas with soils that are naturally acidic, can quickly acidify the soil beyond normal levels;
Strat: lime neutralises the acid pH of the soil;
Deg + Strat: waterlogging of soil managed by addition of organic matter/sand/drainage systems;
\nDeg: reduced organic content through over-harvesting / elevated water table through over-irrigation / lack of use of organic fertilisers;
Strat: improve soil drainage through addition of organic matter/drainage ditches/sub-surface pipes;
Deg + Strat: soil runoff/erosion managed by maintained plant cover all year / reduced grazing / wind breaks/stone walls / contour terracing/ploughing;
\nDeg: caused by soil compaction / overgrazing / leaving land bare means soil may blow away in wind or wash away with rain;
Strat: plant cover/reduced grazing/windbreaks/contour ploughing reduces ability of wind/rain to erode soil.
For each of two examples award [1 max] for named degradation and appropriately linked strategy; 1 mark for development of degradation i.e. its cause/effect; and 1 mark for development of management strategy i.e. how it works:
\nAward [5 max] if no named farming system.
Award [3 max] if no explanations.
[6 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nIncreasing Ecological Footprint (EF):
equation I = PAT (Impact = Population × Affluence × Technology) predicts that increasing economic development (affluence) will increase a population’s impact on the environment/ecological footprint;
economic development (ED) may increase the use of resources/desire for material goods and thus increase the EF of a population;
as demand for power from electricity, if electricity generation is from fossil fuels or nuclear power, EF will increase (due to area needed for waste assimilation);
as population becomes richer meat consumption usually increases, (increasing the area of land needed agriculture), increasing EF;
waste generation increases with increased consumption, increasing EF;
Decreasing EF:
ED may mean a move to renewable energy production (decarbonised society) (reducing need for land to assimilate waste);
ED may increase use of technology to reduce waste production / increase energy efficiency, decreasing EF;
ED may increase education level of population about environmental problems leading to a reduced EF;
ED may slow or decrease population growth and thus reduce impact of population on EF;
ED normally associated with increasing urbanisation which leads to greater efficiency of the population, thus reducing EF;
Countries with strong cultural/religious/ecocentric values may be more likely to regulate their ED to reducing/restricting EF.
Conclusion should be a clear statement of effect of ED on EF that is supported by evidence given in response.
\ne.g. generally ED leads to an increase in EF but this can be dependent on geographical location/cultural/religious background e.g. simple lifestyles / predominantly vegetarian diets;
ED has often lead to increasing EF in the short term, but as EVS are shifting / alternative technologies are available there may well be a longer term reduction in EF.
Conclusion should be a clear statement of effect of ED on EF with supporting statements.
Award [7 max] if no clear conclusion regarding relative strengths or weaknesses.
Award [5 max] if only strengths or limitations discussed.
Award [3 max] if EF is not explicitly discussed.
[8 max]
\nExpression of ideas [2 max]
\nWas rarely answered well, candidates were able to identify a climatic factor, but usually couldn’t elaborate or identify and edaphic one so clearly. The effect on the final climax community was often missing.
\nCandidates mostly got four points on this question, they usually identified one degradation example with a strategy, explanation was often lacking.
\nCandidates who answered this generally identified that increased economic development led to more resource consumption, and sometimes they would link it to consumption of meat. Another marking point they would occasionally earn was that increased economic development could reduce footprint with technology. After these points, very little was clearly identified. Even those candidates who successfully answered the question often missed out a conclusion.
\nOutline two historical influences on the development of the modern environmental movement.
\nDescribe two possible methods that could be used to collect data for a baseline study for an environmental impact assessment.
\nEvaluate the proposal to convert an area of tropical rainforest into agricultural use.
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
Al Gore produced film, “Inconvenient Truth”;
this raised international awareness about global warming;
Rachel Carson published book, “Silent Spring”;
this raised awareness about impact of pesticides/DDT on ecosystems / encouraged establishment of EPA in US;
Industrial revolution led to high levels of atmospheric pollution;
the impact of this on human health/living standards promoted great public concern/interest in pollution;
John Snow made connection between water quality and spread of cholera/water borne disease;
this led to public concern to manage water quality standards/introduce water treatment;
Passenger pigeon in US became extinct through overhunting;
this unexpected extinction led to first conservation efforts in US / Woodrow Wilson setting up first National Parks;
Wackernagel & Rees introduced concept of ecological footprint;
this model has gained widespread recognition as a means of evaluating environmental impacts of societies/populations.
For each of the TWO examples, award [1 mark] for naming and stating influential action and [1 mark] for describing/developing their influence on environmental movement
\n[4 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nEvaluating species’ abundance:
identifying sample points through random coordinates/along transect to cover area of development;
employ sampling method appropriate for given species e.g. quadrats/traps/sweep nets;
calculate total abundance from sample nos e.g. through extrapolation of sample size/Lincoln index/mark-release-recapture;
Evaluating ecological significance/diversity:
survey area obtaining comprehensive species list/no of species/species richness;
identify any species of special interest/Red List Status/local breeding/feeding grounds;
use abundance data to calculate diversity index/Simpsons Index;
quantify current status of ecosystems using a biotic Index;
Evaluating abiotic variables:
identify those abiotic variables most relevant/likely to be impacted by the development e.g. pollutant levels/water temperature/soil qualities;
design a sampling regime to cover relevant area/seasonal variations/diurnal variations/max-min ranges;
select appropriate instrumentation for recording abiotic factors e.g. temperature probes/pH meters/atmospheric particle collectors;
Evaluating social factors:
distribute questionnaires to local population to identify responses/opinions regarding development;
set up community meetings of different constituencies e.g. developers/commercial/residential/environmentalists;
carry out surveys/research to establish current economic/employment/land ownership/land use issues associated with proposed area.
[6 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nReasons to not convert tropical rainforest (TRF) into agricultural use:
TRF contain high levels of biodiversity/ are significant hotspots;
when TRF is the home of indigenous people, we can't suppress their rights (to have a decent living);
TRF provide important ecosystem services of global value / have high intrinsic value;
e.g. carbon storage / involvement in water cycles / oxygen production;
TRF normally have nutrient poor soil due to fast cycling of nutrients in tropical climate;
soils in tropics vulnerable due to high levels of rainfall;
…which can contribute to loss of top soil / loss of productivity / landslides;
Reasons to convert tropical rainforest (TRF) into agricultural use:
may lead to employment opportunities for local populations;
economic development may lead to investment in local medical and education facilities;
produce a greater income for country leading to development;
high population/growth rate may entail that this conversion is the only means to feed local community;
exploitation of limited areas may provide income to support conservation/reduce exploitation of larger areas. [1 max]
Conclusion should be a clear statement of whether the conversion should go ahead and be justified by evidence given in the response.
\ne.g. conversion should not go ahead because despite short term gains, in the longer term it is not sustainable;
conversion should go ahead where it is necessary for the subsistence of local populations but should be limited to more eco-friendly agriculture e.g. coffee and spice plantations/polyculture/integrated agriculture which reduce the ecological value of the forest less than large scale monoculture.
Conclusion should be a clear statement of whether the conversion should go ahead with supporting statements.
Award [7 max] if no clear conclusion regarding relative strengths or weaknesses.
Award [5 max] if only strengths or limitations discussed.
[8 max]
\nExpression of ideas [2 max]
\nIf the candidate was able to identify a historical influence they usually handled it very well, but some very vague influences were mentioned.
\nCandidates rarely performed well in this question, they tried to determine species abundance or diversity but without much detail of how to do it, probably due to lack of teaching of ecological methods. Social factors were rarely addressed.
\nMost candidates answered this questioned successfully. Most could identify the loss in biodiversity and the strongest candidates discussed the vulnerability of TRF soils. Mostly in Q3, (a) & (c) were well answered.
\nOutline why top carnivores are vulnerable to non-biodegradable toxins.
\nExplain two factors which lead to a loss of marine (ocean) biodiversity.
\nEvaluate one possible pollution management strategy for solid domestic waste.
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
organisms lower down food chain/plants absorb small/non-lethal amounts of toxin (into their fatty tissue/biomass);
as the toxin is non-biodegradable it stays in the organism’s body/is not broken down/is persistent, it accumulates over time (bioaccumulation);
toxin is then passed on to further trophic levels through feeding;
because non-toxic biomass is lost (through respiration/metabolism) along food chain but the mass of toxin is not, its concentration increases (biomagnification);
so concentration of toxins increases as it passes up the food chain / concentration increases by an average of 10 times per level (assuming an ecological efficiency of 10%);
...so impact on health of top carnivores is more severe/lethal than lower trophic levels.
Do not credit the response that “higher trophic levels eat more than lower trophic levels”.
\n[4 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
Factor (F): global warming;
Explanation (E): leads to higher ocean temperatures to which many marine species are sensitive;
Explanation (E): some species cannot adapt/evolve/migrate quickly enough / compete successfully, leading to loss in biodiversity/extinction;
Explanation (E): changing temperatures may reduce productivity by phytoplankton leading to loss of diversity throughout the food chains;
Explanation (E): higher temperatures may lead to coral death/bleaching affecting whole food webs/ecosystem;
Factor (F): ocean acidification;
Explanation (E): leads to coral bleaching (especially at higher ocean temperatures);
Explanation (E): most marine organisms have a very narrow band of tolerance for pH (shells won’t develop) leading to possible extinction and loss of biodiversity;
Factor (F): pollution from plastic;
Explanation (E): tiny pieces of plastic ingested by organisms may carry associated persistent organic pollutants(POPs)/toxins that can be absorbed and passed along food chains;
Explanation (E): marine organisms become entangled in plastic and unable to feed/suffocate;
Explanation (E): marine organism/scavenging birds ingest plastic causing suffocation/starvation;
Factor (F): pollution from oil spills;
Explanation (E): oil spills will take long time to degrade, having a long term negative impact on ecosystems and biodiversity;
Explanation (E): oil leading to animals losing their protection to cope with cold/waterlogging/drowning;
Factor (F): overfishing/unsustainable fishing methods/hunting of keystone species;
Explanation (E): some fishing methods (e.g. bottom trawling, electrocution/poison/explosives) are indiscriminate and take all organisms leading to the loss of all organisms from an area;
Explanation (E): some fishing methods destroy the habitats (e.g. scallop dredgers or bottom trawlers) leading to local loss of diversity;
Explanation (E): if fish populations are harvested at rates greater than replacement then loss of numbers will lead to possible (functional) extinction;
Explanation (E): nets and fishing lines can entangle seabirds (especially Cormorants) and marine mammals (e.g. fur seals in Sub-Antarctic);
Explanation (E): Hunting top carnivores e.g. shark can disturb food webs leading to loss of diversity.
Award [4 max] if only one factor explained.
Do not give credit for more than 2 factors. Only credit “eutrophication” as a factor if it is specifically identified in the context of estuarine/shallow water/coastal waters (it is not relevant to oceans/marine systems at large).
[6 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nAnswers may include: recycling, incineration, landfill, composting, altering behaviour e.g. Recycling:
\nStrengths:
in general recycling reduces the amount of energy and resources required for a product;
e.g. the amount of energy saved when recycling aluminium is 95 %
e.g. plastic is usually made from oil which is a non-renewable resource and thus recycling saves a valuable resource;
recycling reduces air pollution and carbon emissions in comparison to a pollutionmanagement strategy (PMS) such as incineration;
recycling can be managed in many ways, such as a doorstep mixed collection, household sorting, drop-off at recycling points, and in less developed countries, by individuals picking through discarded rubbish/trash;
Limitations:
at the moment recycling is often not economical as it is cheaper to produce items from new raw materials;
recycling may not encourage a change in behaviour towards reducing rubbish/trash/garbage;
recycling is challenging for plastics as there are many grades of plastic and you can’t “upcycle” poorer grade plastics;
people may not want to sort their trash when recycling is only available through separation by households;
it is not possible to recycle all products due to poor packaging design.
Conclusion should be a clear evaluative statement of the named pollution management strategy that is justified by evidence given in the response.
[1 max]
e.g. recycling is a particularly effective management strategy because, unlike landfill/incineration/composting, it not only reduces waste but also reduces demand on natural resources;
e.g. recycling is a very effective way of reducing the impact of waste on the environment, but since it depends on altering human activity it will only become really successful with a shift to more ecocentric value systems;
Award [7 max] if no clear conclusion regarding relative strengths or weaknesses.
Award [5 max] if only strengths or limitations discussed.
[8 max]
\nExpression of ideas [2 max]
\nCandidates usually earned one or two marks, but only a handful of candidates could demonstrate a true understanding of biomagnification. Very few scored the maximum 4 marks as there is confusion on the terms bioaccumulation & biomagnification.
\nThis question was handled well by many candidates. They could usually identify two factors easily, with at least one explanation for each, but few achieved the full marks since they lacked depth.
\nMost students identified a couple of advantages and disadvantages for their chosen strategy. Q4 was the most popular. Similarly, the case on Pollution Management Strategy’s (Q4c); most achieved 3-5 marks. Some excellent responses. Lacking detail, thorough explanation of the content.
\nDistinguish between the causes of recent global warming and those of ozone depletion.
\nExplain the impact of global warming and ozone depletion on coastal ecosystems.
\nEnvironmental value systems may lead to different approaches to addressing the issue of global warming. Discuss which environmental value system(s) you consider to be most appropriate in the management of global warming.
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
Gases involved:
for GW are CO2/CH4/CFCs (whereas) for OD are halogen containing gases/CFCs/NOx;
Human activities responsible:
for GW are human causes are very diverse (whereas) for OD more limited;
for GW include burning fossil fuels for transportation/agriculture/heating / rice culture / deforestation (whereas) for OD include refrigeration / spraying / cleaning electronics;
Mechanism;
for GW involves GHGs trapping more infra-red/heat (whereas) OD involves chemical breakdown of ozone molecules;
for GW involves increase in mean global temperature (whereas) OD involves more UV passing through atmosphere;
Distribution:
GW occurs globally (whereas) OD is concentrated around the poles;
OD is caused largely by MEDC activities (whereas) LEDCs make significant contribution to GW through deforestation/rice culture.
[4 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
Global Warming:
is affecting coastal ecosystem globally;
as coastal waters become warmer leads to an increase in productivity from phytoplankton;
but in some areas, waters may become too warm for locally adapted phytoplankton reducing productivity;
warmer waters hold less dissolved oxygen and may become less able to sustain larger organisms;
increase/decrease in productivity of phytoplankton will have the same impact on the entire ecosystem;
coastal ecosystems may contain coral reefs which are prone to bleaching in warmer temperature;
changing temperatures changes ecosystem characteristics and may allow invasive species to colonise an area;
sea level rise may cause coastal erosion;
change in ocean currents/El Nino patterns may bring in more nutrients increasing productivity / or the exact opposite: may deprive coastal areas from nutrient inflow thus decreasing productivity;
Ozone depletion:
may be more important in southern oceans or northern oceans around coastlines as ozone hole is greater near the poles;
Increases mutation rates in phytoplankton changing ecosystem dynamics;
ozone depletion differential reduces productivity of phytoplankton (some more than others);
reduced primary productivity has knock-on effects for entire ecosystems and may reduce population sizes of consumers and secondary productivity of ecosystem;
increased UV may cause health effects/reduce viability of marine animals e.g. young fish/shrimp larva/sea urchins living in coastal waters.
Award [4 max] if only global warming or ozone depletion considered.
\n[6 max]
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
\nPlease note: although \"quality of expression\" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.
Ecocentric approaches:
promote education about global warming as a way to change human behaviour causing the problem;
promote energy efficient strategies in order to reduce production of greenhouse gases (GHG);
promote greater use of public transport / reduced flights / car sharing in order to reduce GHG production;
promote changes in diet to reduce meat consumption and thus reduce meat industry’s contribution to GHGs;
small communities, self-sufficiency / reduction of food miles, reduced consumerism - so less production GHG;
Anthropocentric approaches:
financial incentives to change behaviour such as tax credits for using renewable energy/increasing household energy efficiency;
market based solutions such as carbon trading will incentivise companies to reduce carbon emissions;
legislation in the form of taxation on high carbon emissions;
legislation by government to reduce carbon emissions / e.g. international negotiated treaties/government targets/regional targets for carbon emissions;
community based initiatives such as meat free Mondays to reduce meat consumption and therefore community carbon footprint;
Technocentric approaches:
promote adaptation to new conditions that result from global warming;
increase research and development for new fuels/renewable/nuclear energy / carbon capture technology;
invest in geoengineering solutions to reduce effect of greenhouse gases;
promote development of new technologies to reduce carbon emissions such as more fuel efficient cars/electric cars/hybrid cars.
Award [4 max] if only one EVS is discussed.
Award [2 max] for a personal conclusion regarding which EVS is most effective in managing global warming that is justified by evidence given in the response e.g. although I would personally favour an ecocentric approach because I think this addresses the root cause of environmental degradation...;
...the technocentric approach goes a long way to conserving the environment while allowing for the continuing economic development that seems so inevitable;
Award [7 max] for responses with no personal conclusion.
[8 max]
\nExpression of ideas [2 max]
\nMany candidates often had some partial understanding of GW and OD, but often failed to make clear distinctions. The command verb posed a high difficulty so students achieved low scores for this question.
\nThose candidates who understood the difference between GW and OD would generally earn a couple of points for global warming, and identify one for OD. Most students will describe mostly terrestrial ecosystems. Students seemed to lack understanding on the subject since they mainly got 3-4 marks at the most on this question.
\nCandidates seemed to have some understanding on the characteristics of the value systems but many failed to apply them specifically to strategies to address GW. The main problem remains the reading and interpretation of the question. It seems that if the question includes \"Environmental impact assessment\" they explain everything they know about EIA without actually answering the question.
\nDefine the term carrying capacity.
\nIdentify three reasons why carrying capacity can be difficult to estimate.
\nthe maximum number of individuals/load of a species that can be sustainably supported by a given area/habitat/environment OWTTE;
\nNB. Definition needs to make clear that cc is associated with a single species. This means that: “The maximum number of a species that can...etc” is acceptable, but “the maximum number of species that can…” is incorrect, and should not be credited.
\nGenerally:
there are many different potential limiting factors for natural populations;
populations’ needs may change through time due to genetic changes/evolution;
environmental conditions may change eg climate change/introduced species;
it takes extensive/long-term study to identify a precise relationship between a species and given environmental factor;
For human populations:
human populations exploit/depend upon a far greater range of different resources than most other species;
(human ingenuity) humans are able to substitute one resource/material for another;
variations in lifestyle/culture/economic status between human populations mean different resources/amounts of resources are used/needed;
the importation of resources from other ecosystems/regions can offset a lack of resources in an area;
technological developments cause changes in resources required/available over time;
Award [1] for each correct reason identified, up to [3 max]
\nDo not credit responses addressing changing population size (has no influence on carrying capacity).
\nAlthough, in other contexts, allowances are made for linguistic imperfections, for the purpose of a “define” question, language does need to be precise. For example, in response to this question the phrase “maximum number of a species” means something quite different to “maximum number of species” …and many responses used the latter concept which is incorrect. Similarly, a number of responses omitted the key element of “sustainably” (i.e. as in “…can be sustainably supported”)
\nCandidates often found one valid difficulty in estimating carrying capacity but few went further. A significant minority confused the estimation of carrying capacity, with the estimation of population size.
\nFigure 2: Map to show the location of Yasuni National Park in Ecuador,
a globally significant high biodiversity area
[Source: © International Baccalaureate Organization 2017]
\nDefine biodiversity.
\nWith reference to Figure 2 identify three factors that could explain the high biodiversity in Ecuador.
\nFigure 3: Table to show the species richness of Yasuni National Park
\n[Source: Margot S. Bass, Matt Finer, Clinton N. Jenkins, Holger Kreft, Diego F. Cisneros-Heredia, Shawn F. McCracken,
Nigel C. A. Pitman, Peter H. English, Kelly Swing, Gorky Villa, Anthony Di Fiore, Christian C. Voigt and Thomas H. Kunz,
‘Global Conservation Significance of Ecuador’s Yasuní National Park.’ PLoS One, January 19, 2010.
https://doi.org/10.1371/journal.pone.0008767]
Describe a method that may have been used for collecting the tree data in Figure 3.
\nbiodiversity is a broad concept encompassing the total diversity of living systems / biodiversity includes the species, habitat and genetic diversity within an area / the amount of biological diversity per unit area; OWTTE;
\nAward [1 max] for a correct definition.
\nclose to the equator/high primary productivity/favourable climate/highrainfall/insolation;
(Ecuador is in latitude of) tropical rainforest biome (which is a biodiversity hotspot);
(greater species/genetic diversity due to) high habitat diversity/climatic zones/biomes/range of coastal/lowland/forest systems;
active plate tectonics creating barriers to populations (and so encourages speciation);
altitude variation on mountains (create zonation/diversity of habitats);
active plate tectonics enabling succession (from volcanic material/lava/lahars etc);
large protected area/national park;
Award [1] for each correct factor identified, up to [3 max].
\naerial photograph;
identify from the leaf canopy the different species seen;
OR
\nuse quadrat sampling/sampling points along a transect;
identify and count all the different species seen in quadrats/along transect;
OR
\ncollect live specimens of leaves/fruits/seeds etc from the unit area;
have them identified (in labs) using keys/expert botanists;
Award [1] for each step identified up to [2 max].
\nDo not credit responses that address abundance rather than number of different species.
\nA good proportion of candidates were able to give a valid definition of biodiversity, though many confused the term with species diversity.
\nThis was well answered. Great majority of candidates had the basic analytical skills to identify three geographic features that contributed to high biodiversity.
\nMost were able to suggest a valid practical method for finding number of tree species, though some mistakenly addressed methods for measuring abundance, or Simpson’s diversity index, or even the Lincoln index (for moving animals).
\nFigure 5: A layer of smog covering the Chilean city of Santiago
\n[Source: CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=428144]
\nIdentify one human factor that contributes to photochemical smog.
\nIdentify one natural factor that contributes to photochemical smog.
\nExplain why the formation of photochemical smog may have harmful effects on the environment of cities such as Santiago (Chile).
\n(intensive) combustion of fossil fuels/organic matter/through high density traffic/urbanisation/industrialisation/forest burning/release of VOCs from aerosols;
\nlocal topography/high insolation/sunlight/low wind/thermal inversion;
\nreduced growth and productivity of plants/reduces crop yields by damaging them;
leads to the reduction of the air quality/visibility/ambience within the urban area;
particulates/chemicals within the smog enter the lungs and irritate respiratory system/cause respiratory disease/lung cancer;
particulates/chemicals within the smog may cause irritation of eyes/eye diseases;
the chemicals within the smog react with plastic/rubber causing it to perish/become hard/inflexible;
tropospheric ozone (a secondary pollutant) is a greenhouse gas/contributes to global warming/climate change;
smog pollutants reduce immune system of humans and animals (become more susceptible to diseases);
Award [1] for each correct explanation, up to [4 max].
\nMost were able to identify a valid human factor contributing to photochemical smog, though a good number mistakenly identified CO2 from fossil fuels.
\nA slim majority were able to identify one natural factor.
\nVast majority were able to identify at least one impact of smog but very few identified four for full credit.
\nFigure 6(a): Map showing distribution of birch forest in 874 and in 2015
\n[Source: Map drawn by Björn Traustason, Icelandic Forest Service (www.skogur.is). Used with permission.]
\nFigure 6(b): Map showing soil erosion in Iceland in 2007
\nFigure 6(c): Model to show changes in vegetation cover during the six stages of soil degradation in Iceland
\nFigure 7(a): Fact file on Nootka lupin
\n[Source: Icelandic Institute of Natural History]
\nFigure 7(b): Known distribution of lupin in 2010
\nThe resource booklet provides information on Iceland. Use the resource booklet and your own studies to answer the following.
\nWith reference to Figures 6(a), 6(b), 6(c) and 7(b) identify two ways in which vegetation cover has changed over time in Iceland.
\nOutline two ways in which human activity may have increased soil erosion in Iceland.
\nWith reference to Figures 6(c), 7(a) and 7(b) explain the problems associated with land restoration in Iceland.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nvegetation cover has been significantly reduced;
change from woodlands to heath/moor/shrubs/desertified/bare landscape;
extent of birch forest has reduced (significantly/by more than half);
increase in coverage of lupins;
lupins replace/outcompete native flora;
Do not accept change from ‘vegetation cover to desertified landscape’
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ndeforestation has exposed the soil to erosion/made soil more prone to erosion/resulted in loss of root system that holds the soil in place;
overgrazing by livestock has prevented regeneration of vegetation/exposed soil to erosion;
climate change/global warming/higher temperatures has led to melting of ice and increased floods causing soil erosion;
trampling on ground can reduce vegetation and expose soil to erosion/cause soil particles to break away and increase erosion/cause soil compaction that increases runoff and associated soil erosion;
NB Only credit if reason given is explained, do not accept only \"logging/deforestation/overgrazing/trampling/soil becoming compact/climate change/global warming\" without an account of how this impacts erosion.
Accept other reasonable responses.
\n
This question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ncan be expensive/labour intensive/the longer you leave it the more it costs;
the longer you leave it the lower your chance of success/chance of success is lowered with time/greater stage of vegetation loss;
strategies may have unforeseen/unpredicted effects;
eg lupins (introduced to control soil erosion) are invasive/outcompeting native species/have become a large-scale problem/have spread across the island;
eg herbicides may cause water pollution/adversely affect other species;
eg mowing/grazing/pulling up lupins can increase soil erosion;
harsh climate may make it difficult;
cause of problem may be external/global eg climate change;
reduction/low in soil nutrients/poor soils;
Accept other reasonable responses.
\nLevel of success must be linked to time period/stage of vegetation loss to be credited the mark. Do not accept removal of lupins increases cost of restoration.
\nAlthough there were some very good answers, a significant number of candidates discussed the reasons for lack of vegetation and soil erosion levels rather than focusing on the actual change in vegetation cover.
\nFew candidates answered this question well. Some responses confused soil erosion with soil degradation. Many answers were too vague and just stated ‘farming’ or ‘grazing’ without explaining how these activities increases soil erosion.
\nMost candidates achieved some marks for this question by identifying the introduction of lupin, an invasive species as a key problem. Candidates that were also able to interpret the data in figure 6c appropriately achieved full marks.
\nThe resource booklet provides information on Iceland. Use the resource booklet and your own studies to answer the following.
\nEvaluate the possible impacts of climate change on Iceland.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nPositive effects [3 max]:
increase in temperature leads to increase in agriculture/farming productivity;
migration of new species might lead to increase in fishing industry;
forest growth at higher altitude may lead to less erosion;
increase in hydroelectric power as more water in glacial rivers;
increase in temperature lowers heating costs in a cold country;
melting of ice/glaciers could make available land for agriculture/forest;
provide favourable conditions for more species/which increases biodiversity;
Negative effects [3 max]:
reduction in population numbers (eg puffin) due to reduced food sources/may have a detrimental effect on reproduction/species unable to adapt to change in climatic conditions;
loss in biodiversity/extinctions;
shifts in food webs as new species arrive/shifts in food web as some species are lost;
economic loss due to reduction in potential catch in fishing industry/loss of some species could result in loss of food supply for humans;
volcanic eruptions more likely as ice melts;
long term decline in hydroelectric power as melt water decreases;
reduced tourism due to loss of attractions eg ice caps/loss of wildlife;
increased precipitation may lead to increase in soil erosion/increased precipitation could increase leaching of nutrients from the soil;
melting of ice/glaciers could cause flooding/increase soil erosion;
melting of ice/glaciers could reduce stores of potential drinking water;
rise in sea levels could cause coastal flooding;
loss of ice/snow could reduce albedo effect/increase heat absorption and lead to further warming;
melting of permafrost will release greenhouse gases/methane/carbon dioxide;
Opinion/Appraisal statement (that is substantiated with evidence) [1 max]:
eg short-term benefits may be accompanied by long-term problems;
Iceland is going to need to be adaptable as economic opportunities must be balanced by losses;
effects may not be known for some time due to multiple factors/feedback/complexity of systems;
Overall climate change will have a positive effect … as the warmer temperatures will allow for greater growth of trees that help conserve the soil/result in greater agricultural yields whereas loss to the limited number of endemic species on the island is likely to be minimal;
Max 4 marks if there is no opinion/appraisal.
\nDo not accept only ‘temperature increases productivity/vegetation’ without explanation of how this is a benefit.
\nMarks achieved for this question varied widely. There were some good responses although a number of students made no or little attempt at the question. Others gave answers that were too vague eg ‘climate change impacts species’ without explaining how and what the impacts of this could be. Most responses lacked any final appraisal.
\nFigure 8(c): Food web for the Atlantic puffin
\nFigure 8(d): Graph showing global capture fisheries of Atlantic herring in tonnes 1950–2010
\nThe resource booklet provides information on Iceland. Use the resource booklet and your own studies to answer the following.
\nIdentify one argument in favour of humans hunting puffins.
\nIdentify one argument against humans hunting puffins.
\nWith reference to Figure 8(c) state the impact that an increase in the mackerel population might have on the Atlantic puffin population.
\nIdentify two reasons why the future size of the Atlantic puffin population is difficult to predict.
\nWith reference to Figure 8(d) identify two factors which may account for the changes in total capture of Atlantic herring.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ncultural/traditional practice for Icelanders;
they are not locally endangered;
legally allowed in Iceland;
source of protein/food;
economical value;
puffin meat/products may attract tourists;
hunting puffins reduce competition for fish stocks;
\n
This question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nknock-on effects on food web;
biorights of puffins/intrinsic value of puffins;
population in decline;
status may change from vulnerable to endangered/extinct;
if over-exploited will not be a sustainable source of food/will cease to be a source of food;
Do not accept only ‘puffins are vulnerable’.
\nnumber of puffins could decline (as mackerel eat their prey/competition for food sources);
\nDo not accept only ‘there is less food available for puffins’.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nmultiple interrelated threats affecting them;
impact of extreme weather/impact of climate change not fully understood;
unexpected diseases may affect population numbers;
inaccuracies in population counts;
large geographical range makes representative sampling difficult;
difficult to predict future number of prey species/food availability/difficult to predict number of competitors (eg mackerel);
calculations only based on estimates with large margin of error;
in future changes may be made to the management/legislation/policies on puffins (eg hunting of puffins may be banned);
NB Do not credit for only over-hunted/overfishing/is part of a complex food web/‘weather’.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nincrease in catch due to more boats at sea;
increase in catch due to improvements in technology;
increase in catch due to extended fishing grounds;
increase in catch due to recovery of fishing stocks from over harvesting;
improved fishing technology/over-fishing may lead to reduced populations over time resulting in reduced catches;
reduction in catch due to less number of boats allowed to fish/increase in mesh size of nets;
reduction in catch due to more strict regulations/reduced quotas/total allowable catches/regulations to restrict catches/increase in catch due to increase in quotas/total allowable catches;
increased number of predators may reduce population of herring/reduction in number of predator (eg puffin) may increase population of herring/reduction in prey reduces herring population/more available prey may result in an increase in the population of herring;
changes in demand for herring from markets results in an increase/decrease in catches;
climate change may cause changes in distribution and populations that result in an increase/decrease in catches;
NB A correct reason must be linked to either a rise or fall in the amount of captured Atlantic herring to be credited a mark. Restricting/limiting fishing can be considered as a reduction in fish catches.
\nMost candidates answered this question well.
\nMost candidates answered this question well. A common error was to state that puffins are vulnerable without commenting how hunting could further reduce its population numbers or alter its IUCN classification to endangered.
\nA common error was to explain there was competition between mackerel and puffins but not to suggest that this could result in a reduction in puffin population.
\nMany students answered this question well. The most common responses were extreme weather conditions and availability of food.
\nFew candidates answered this question well. Many gave generic answers eg ‘use of quotas’ without linking their answer to the increase or decrease of catches illustrated in figure 8d.
\nFigure 2: Fact file on Iceland
\n[Source: Open access/Wikipedia]
\nFigure 9(a): Graph showing primary energy consumption in Iceland 1940–2008
\nFigure 9(c): Pie chart showing sources of greenhouse gas emission in Iceland in 2010
\nWith reference to Figure 9(a) outline how Iceland’s primary energy consumption has changed over time.
\nWith reference to Figure 2 and Figure 9(c) outline two possible reasons why energy demand declined in Iceland after 2008.
\nthe energy consumption has increased overtime (from 1940 to 2008);
in 1940s/initially energy consumption was reliant mainly on coal;
in 2008/more recently it was predominantly reliant on geothermal/renewable energy/ has relatively little reliance on fossil fuels/coal/overtime it has changed from being mainly coal/fossil fuels/non-renewable to geothermal/renewable energy;
from around 1940-1970 there is a steady growth in consumption/greater use of oil and geothermal;
from 2004/05 there is a rapid increase in consumption/expansion of geothermal and hydropower;
Accept other responses that correctly link the change in growth in energy or the balance of energy sources to the time period.
\neconomic crisis in 2008 led to industrial decline /reduction of demand for aluminium world-wide;
following economic crisis, households had less money/tighter budgets and therefore reduced energy use;
industry accounts for the largest share of energy consumption (40 %);
deliberate efforts to reduce consumption through energy conservation
Do not accept only ‘2008 economic crisis has led to reduction in energy demand’ without explanation or ‘emigration could reduce energy demand'.
\nThere were some good responses that linked the increase in energy consumption and the changing mix of energy sources to specific time periods. Common error was not to refer to the time period being discussed or incorrectly interpreting the graph and suggesting coal and oil were the most used energy sources in 2008.
\nFew candidates achieved full marks for this question. Many responses identified ‘economic crisis’ but did not link this to reduction in industrial activity and therefore reduction in energy demand. Another common error was to assume that changing to renewable energy sources reduces energy demand.
\nIdentify four reasons why the genetic diversity of a population may change over time.
\nExplain how changes in the concentration of stratospheric and tropospheric ozone in the atmosphere can affect global biodiversity.
\nEnvironmental value systems differ in how they view the importance of biodiversity and this could influence a community’s approach to conservation.
\nDiscuss how these different perspectives, including your own, may influence approaches to conservation.
\nmutation may lead to new genotypes/increased diversity;
\nnatural selection/survival of fittest may eliminate some genotypes/reduce diversity;
\n(human activities) eg pollution/hunting/habitat destruction/alien species may reduce population/diversity / lead to a bottleneck effect;
\nmigration causing mixing of populations/subjection to new selective pressures;
\nclimate change may eliminate certain genotypes/reduce diversity;
\n…or lead to evolution of new genotypes/increase diversity;
\n(tectonic activity may create) natural barriers leading to divergent evolution/speciation/greater diversity;
\ngenetic drift/random loss of genes;
\nmixing of GMOs/selectively bred/farmed escapees introduces new genes to wild populations.
\nAccept any other reasonable suggestions.
Responses that identify relevant factors eg “mutation”, but do not identify why/how this influences diversity should not gain full credit.
Award [1 max] for responses that list three valid factors without identifying how they influence diversity.
Award [2 max] for responses that identify four such factors.
Award [1] for each correct reason identified, up to [4 max].
Award [1] for the following point:
\nstratospheric ozone has decreased and (production of) tropospheric ozone has increased;
\nAward [1] for each part of the explanation given below, up to [6 max].
\nchange in stratospheric ozone allows more UV radiation to reach earth;
…which causes mutations/damage to DNA/cancers;
…(possibly) resulting in death of organisms/reduction in biodiversity;
…also reduces plant growth/NPP/especially phytoplankton / damages chlorophyll;
…affecting populations all along food chain/reducing diversity of food web; [4 max]
change in tropospheric ozone in urban areas gives rise to photochemical smog;
…that is toxic (to humans/other species);
…damages plant leaves reducing NPP of ecosystems/food chains;
…tropospheric ozone is a greenhouse gas contributing to global warming/climate change;
…resulting in population declines/death/reduction in biodiversity; [4 max]
Do not credit the common misconception that ozone depletion/UV radiation leads to global warming (its connection, if any, is negligible).
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nQuestion 7 was the most popular choice. A good proportion of candidates could identify at least a couple of factors affecting genetic diversity although further answers were commonly too vague for full credit, e.g. human influence; genetic engineering. A significant minority mistakenly addressed species diversity in communities.
\nA significant minority showed a clear understanding of the differences between stratospheric and tropospheric ozone and their impacts. However, a large majority showed profound confusion by linking ozone depletion in stratosphere with global warming and climate change. Many made no distinction between stratospheric and tropospheric ozone.
\nMost candidates were able to distinguish different value systems …although their distinctions were commonly vague and somewhat caricatured/simplistic. A significantly smaller group were able to link the value systems with specific conservation strategies/approaches.
\nThe resource booklet provides information on Iceland. Use the resource booklet and your own studies to answer the following.
\nTo what extent might Iceland be viewed as a role model for sustainability by other countries?
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nIt is a model for sustainability because [max 4 marks]:
renewable energy accounts for a very high percentage of energy consumption (aim of 100% by 2050)/reduced reliance on fossil fuels that produce GHGs;
use of renewable energy sources instead of fossil fuels allows for sustainable development where the needs of the present are met without compromising the needs of future generations;
taking steps to address soil degradation by planting lupins;
attempting to remove invasive species;
fish stocks such as Atlantic herring appeared to have increased/recovered (since 1979) suggesting appropriate management;
growth in tourism can be used as a reason to conserve/protect its wildlife/puffins/whales/areas of wilderness/growth in tourism can provide alternative employment to aluminium smelting/industries that can produce significant levels of GHGs;
aluminium smelting which is high energy consumption is located here to make the most of renewable energy;
hunting of puffins is restricted to April/only one month of the year to avoid them becoming endangered/extinct;
It is not a model for sustainability because [max 4 marks]:
Icelanders harvest/eat species (eg puffins), whose numbers are in decline/Iceland legalise hunting/eat puffins that are classified as vulnerable;
Iceland has a very high ecological footprint which is three times the Earth share;
home to industries which produce lots of greenhouse gases (eg aluminium smelting);
there are high rates of soil degradation;
there has been a high loss of original birch forest/woodlands;
invasive lupins/alien species are not fully controlled/a threat to native species/wildlife/habitats;
mass tourism during the summer months can stress wildlife/puffins/whales that can reduce reproductive success/cause injury through tourist boats steering too close;
due to the extent of vegetation loss the chances of successful recovery/restoration are low;
development of hydroelectric power schemes can result in reduction of forest areas/pristine areas of wilderness/disrupt migration patterns of some aquatic species/fish;
government has approved oil exploration in Icelandic waters potentially increasing use of non-renewable resources/unsustainable use of natural capital/risk of oil pollution/further emissions of greenhouse gases;
population has grown significantly since 1800/1900 resulting in greater use of natural resources/resulting in overfishing/overgrazing;
with high rates of vegetation/woodland loss the restoration costs are high with low probability of success;
use of herbicides to remove lupins may adversely affect non-target species/native species;
energy industry (including geothermal)/industrial processes still emits substantial amounts of the Iceland’s greenhouse gases;
Opinion/Conclusion [1 mark]:
Eg While Iceland has a high EF, it is actively working to reduce GHG by focusing on renewable energy and replanting forest/focusing on reducing soil degradation, and therefore can be considered as a role model of sustainability to other countries;
Despite aiming to use 100% renewable energy by 2050, Iceland cannot be considered to be a role model of sustainability for other countries because of its high EF and significant loss of forest that has reduced carbon dioxide sinks/stores and also accelerated soil erosion;
Iceland can be considered as being a model because sustainability is the responsible use and management of resources that allows natural regeneration and minimises environmental damage which is evident in how it deals with its energy requirements;
Iceland cannot be considered as a model of sustainability because this requires responsible use and management of resources that allows natural regeneration and minimises environmental damage and Iceland has poorly managed its land that has caused extreme soil erosion/significant loss of forests;
Note to examiners: An isolated statement/opinion, eg “Iceland is a role model for sustainability”, should not be considered as a valid conclusion. A valid conclusion may, however, be stated within the body of the response rather than at the end, and may involve some balanced decision.
\nMax 5 marks if there is no conclusion/opinion.
Accept other reasonable responses supported by information in the resource booklet.
Some candidates gave a well-argued response covering both points of view on whether Iceland should be considered a model for sustainability, together with a clear conclusion. However, there were a large number of responses that were too generalised and lacked the level of detail required and did not give a clear conclusion supported by evidence. A significant number of candidates did not attempt this question at all.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nIdentify one ecosystem in Algonquin Provincial Park.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nPossible ecosystems include:
deciduous forest/maple forest/beech forest/temperate forest;
coniferous forest/boreal forest/taiga forest/spruce forest/pine forest;
lake;
river/stream;
meadow / beaver meadow;
marsh / beaver marsh;
pond / beaver pond;
wetlands.
Do not accept forest/wood as too general.
Do not accept biomes eg “taiga/tundra biome” or only “taiga”.
The majority of candidates correctly identified an ecosystem present within Algonquin Provincial Park. Incorrect responses included naming a biome e.g. tundra or giving generic responses such as ‘forest’.
\nOutline four different ways in which the value of named resources have changed over time.
\nThe use of renewable resources is not always sustainable due to the activities involved in their production.
\nJustify this statement for a named source of renewable energy.
\nIncreasing concern for energy security is likely to lead to more sustainable energy choices.
\nDiscuss the validity of this statement, with reference to named countries.
\ncultural influence eg rising environmental awareness led to value of straw as building material;
social influence eg animal rights leading to devaluing of animal furs in fashion;
economic influence eg increased investment in industrial processes led to higher value of fossil fuels;
technological influences eg progress in nuclear technology led to higher value of uranium;
political influences eg increasing concern for energy security in US has led to devaluing of oil / increased value of tar sands;
ecological influences eg greater understanding of ecosystems/ecology has led to high value attached to biodiversity.
NB As question does not specify further, and syllabus makes reference to marketable value (price), responses made in such terms should be credited.
Award [1 max] if four influences are identified without examples.
Award [1] for each correct reason identified, up to [4 max].
Valid influences/reasons may not be categorized in precisely the same way as above, but examples need to demonstrate different kinds of influence to gain separate credit.
eg hydropower (accept other valid examples of renewable energy):
hydropower is renewable because the water flow is replenished by the water cycle;
building the dam will inhibit migration of fish reducing their populations;
involve the flooding/destruction of terrestrial ecosystems;
cause sedimentation that will lead to more flooding upstream;
involve use of non-renewable building materials;
construction/maintenance involves heavy use of fossil fuels/GHG production;
reduced downstream flow threatening riverine populations/species;
(reduced downstream flow threatening) associated terrestrial systems dependent on water flow eg floodplains/wetlands;
building of access roads/growth of recreational activity may lead to damage of terrestrial/riparian systems;
may increase water loss/scarcity through increased evaporation rates;
impacts of dam may reduce sustainability of local populations through eg reduced fishing/breeding ground for parasites/loss of agricultural land.
eg solar energy:
solar energy is renewable because of continuous input/insolation;
energy for panel construction/extraction of silicon involves use of fossil fuels/GHG production;
production utilizes plastics derived from (non-renewable) fossil fuels;
manufacture results in plastic waste that is non-biodegradable;
require metals/elements that are non-renewable resources;
(metals/elements) extracted through mining that damages habitats/ecosystems;
manufacture involves use/production of many industrial toxins/hazardous waste;
manufacture/operation requires considerable water supply (for cooling etc);
transport of materials for manufacture/installation impacts environment;
limited life span/decommissioning will lead to further waste;
solar farms can take up/displace large areas of natural ecosystems.
Award [3 max] if example of energy source is non-renewable or unnamed.
Award [1] for each correct answer given above or for any other points of equivalent relevance, validity and significance, up to [7 max].
If candidate addresses more than one valid resource, limit total credit to highest scoring one.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQ7 (a) Question 7 was the most popular choice. In part (a) most candidates could identify the influence of two or three factors on the value of a named resource. Some responses were more limited in their range of influences and gave multiple examples of a similar influence on different resources.
\nMost candidates clearly grasped the essence of the question and many scored well. Weaker responses, however, were too generalised/non-specific to again extensive credit. For example, simply claiming that a dam would “alter water flow” rather than specifying how the flow is altered upstream and downstream and the likely impacts of that alteration. While majority of candidates addressed hydropower as an example, candidates addressing solar or wind power, for example, scored similarly.
\nMost candidates had some grasp of energy security although their grasp was sometimes quite vague. Furthermore, most candidates could give a range of national energy choices as examples and so scored effectively within the 4–6 markband. Only the better candidates were able to effectively and clearly link these energy choices to issues of security as such, and then explore counter examples to produce the balanced analysis/argument necessary for the 7–9 markband.
\nWith reference to Figures 1(b) and 1(c), identify the biome found at the highest altitude in Madagascar.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ngrasslands/woodlands
Must include both grasslands and woodland to be credited.
\n
Most students correctly identified the biome found at the highest altitude. Incorrect answers included ‘dry deciduous forest’ or giving only a partial response i.e. ‘grassland’ rather than ‘grassland/woodland’ as labelled on figure 1c.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nFigure 6: Simplified Algonquin Provincial Park food web
\nWith reference to Figure 6, draw a food chain that includes four trophic levels.
\nIdentify two ways that human activity in Algonquin Provincial Park may affect the food web.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nAward [1] for 4 named species correctly identified as being in the same food chain and [1] for arrows going in the correct direction.
For example:
spruce/maple tree → woodland jumping mouse → red fox → Algonquin wolf
spruce/maple → snowshoe hare → red fox → Algonquin wolf
spruce/maple → fairy moth → grey jay → northern saw whet owl.
Do not accept just “trees/vegetation”.
Do not credit arrows if more than one set of arrows given eg illustrating waste/respiration.
This question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nhunting/trapping/fishing removes species from the food chain / hunting of beavers/moose reduces food availability to predators such as wolves/bears;
logging (forest management) removes species from food chain;
trampling (from tourist)/development of tourism facilities could reduce food source/first trophic level;
introduced species, eg cats/dogs, add additional predators or prey;
removal of dams may lead to loss of pond species eg bullhead lily/dragonfly/bullfrogs/pearl dace reducing food source for other species;
protection of wolves increases wolf numbers, thereby increasing predation on beaver/moose/hare etc. reducing herbivore numbers.
Note: For credit the human activity must be explicitly linked to effect on the food web.
Do not credit if activity is only linked to habitat loss.
Do not accept “deforestation/agriculture or only “pollution”.
Accept other reasonable responses.
This question was answered well with most candidates correctly identifying 4 species and drawing arrows in the correct direction within the food chain. Drawings/sketches of the species are irrelevant and therefore candidates should not use valuable time in the exam doing this. Marks were most commonly lost for arrows pointing in the wrong direction and a few students confused a food chain with a food web or a trophic pyramid.
\nThe majority of candidates only achieved one mark for this question. A common error was to discuss human activities for which there was no evidence within the resource booklet e.g. deforestation or agriculture. In addition, many answers were too vague and did not link the human activity to the effect on the food chain.
\nDescribe the role of primary producers in ecosystems.
\nExplain the potential impact of ocean acidification on environmental systems and societies.
\nTo what extent do anthropocentric value systems dominate the international efforts to address climate change?
\nproducers are plants that convert light energy into chemical energy by photosynthesis;
photosynthesis/primary producers convert carbon dioxide and water into glucose/sugar and oxygen;
this conversion/glucose forms the raw material of biomass/the basis of food chains;
producers (thereby) provide food for consumers/energy in a form that can be passed along food chains;
the production of oxygen by producers is vital for the majority of ecosystems;
the absorption of CO2 maintains a balance of CO2 in atmosphere/reduces global warming;
primary producers may alternatively generate biomass through chemosynthesis;
chemosynthetic bacteria use chemical energy to produce food without using sunlight;
plants may also provide other resources/services for ecosystem eg habitats/soil conservation/cycling of matter;
Award [1] for each correct role described, up to [4 max].
\nocean acidification is caused by increased CO2 levels in atmosphere leading to more CO2 absorbed into ocean;
the CO2 reacts with the water forming an acid (carbonic acid)/decreasing the pH/changing pH from about 8.2 to 8.1;
macro-algae/seagrasses may benefit from higher CO2 conditions in the ocean;
some organisms are adapted to a narrow pH range/very sensitive to pH changes;
low pH/reduces ability of shelled organisms to maintain their shells/reduces reproductive ability in fish/shellfish;
producers eg phytoplankton/corals in ocean environments can be particularly sensitive to low pH;
corals are more prone to bleaching/less able to recover from damage in acidified water;
reduction in producers reduces the resilience of an ecosystem/impacts entire food webs/is a potential tipping point for marine systems/reduces biodiversity;
collapse of a natural ecosystem may lead to collapse of fisheries/collapse of aquaculture (eg oysters)/overfishing of diminishing fish populations;
loss of fisheries can lead to limited food supply for indigenous communities/need to import food;
decline in fishing/aquaculture would result in reduced employment/socio-economic hardship;
coral reefs support economically valuable ecotourism that may be lost/decline;
loss of corals will bring an aesthetic loss/infringe biorights of organisms;
Do not credit responses that mistakenly address acid deposition.
Award 2 max for describing process of acidification.
Award 5 max if impacts are limited only to ecosystems or only to societies.
Award [1] for each correct explanation, up to [7 max].
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nPlease refer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQ4 was the most popular choice in Section B. Great majority were able to identify a couple of aspects of the role of primary producers but few went on to gain full credit.
\nThere were some excellently detailed answers in response to this question, though a great number confused ocean acidification with acid precipitation which have very different causes and impacts. Similarly, many mistakenly addressed contamination of food sources, bioaccumulation etc.
\nAgain there were some very impressive responses that correctly characterised the anthropocentric position and their role in many named international agreements developing a clear argument in contrast to other environmental value systems. A good deal of responses, however, portrayed a rather distorted version of anthropocentrism more along the lines of cornucopian values or climate change sceptics, so the argument became unbalanced or confused.
\nFigure 2: Fact file on Madagascar
\n[Sources: The World Factbook 2018. Washington, DC: Central Intelligence Agency, 2018 https://www.cia.gov/library/
publications/the-world-factbook/index.html and Rhett Butler/WildMadagascar.org]
Figure 3(a): Age–gender pyramid for Madagascar in 2016
\nFigure 3(b): Population curve for Madagascar (1960–2015)
\nWith reference to Figures 2, 3(a) and 3(b), identify two reasons why Madagascar is considered to be at Stage 2 of the demographic transition model.
\nhigh birth rate;
falling/decreasing/declining death rate / increasing life expectancy;
rapid growth in population / growth rate of 2.54% (32.1–6.7/10) / population has increased almost fivefold since 1960 / high rate of natural increase (NIR) / population is exponentially increasing;
population doubling time of 27.56 years (70/(2.54));
wide base of age-sex pyramid / largest age group is 0–4 years / predominantly young population / high proportion of population are children (under 19).
Do not accept only values of either birth rate or death rate e.g. “death rate is 6.7/1000”; response needs to specify whether it is high or decreasing respectively.
Do not accept “low death rate” or just “increase/growth in population”.
Do not accept “crude birth rate is higher/greater than crude death rate” as this is applicable to other DTM stages.
Do not accept only “many/lots of children / more births/many births”.
Do not accept “industry is mostly agriculture/forestry/fishery”.
Most candidates achieved at least one mark for this question. Common errors were to focus on the prevalent industry in Madagascar or give responses that lacked the required detail that differentiated it from other stages of the DTM e.g. stating there is a growth in the population without linking to scale or rate of change or that crude birth rates are higher than crude death rates.
\nFigure 8(a): River before and after beaver dam construction
\nFigure 8(b): Graphs to show nutrient and oxygen content in beaver pond and stream
(Error bars show standard deviation)
Figure 9(a): Fact file on beaver’s role in the ecosystem
\n© International Baccalaureate Organization 2018
\n\n
Figure 9(b): The succession of ecosystems caused when a beaver dam is built across a river
\nWith reference to Figures 8(a) and 8(b), describe the changes in nutrient and oxygen content that occur after beaver dams are constructed. Include quantities in your response.
\nWith reference to Figures 9(a) and 9(b), explain the impacts of beaver dams on biodiversity within Algonquin Provincial Park.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nAward [1 max] for changes in ONE nutrient:
amount of carbon in sediments is 5 % higher in ponds/after construction of the dam / carbon is 20% in pond and 15% in stream;
concentration of phosphate is higher by 1.1 mg kg–1 in ponds/after construction of the dam / phosphate concentration is about 1.15mg kg–1 in the pond compared to about 0.05mg kg–1 in both streams;
concentration of nitrate is higher by 0.75 mg kg–1 in ponds / nitrate concentration in pond is 2 mg kg–1 compared to 1.25mg kg–1 upstream/site A / nitrate concentration in pond is 2 mg kg–1 compared to 0.25mg kg–1 downstream/site C.
Award [1 max] for changes in oxygen:
concentration of dissolved oxygen is lower by 9 ppm in ponds / oxygen concentration in pond is 3ppm compared to 12 ppm upstream/downstream/after construction of the dam.
Note: Figures do not need to be exact for nitrates or phosphates but some quantification is required.
Do not accept phosphate levels are negligible.
This question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ndams reduce stream velocity/water flow creating ponds/marshes/additional habitat diversity / beaver ponds create new habitats for different aquatic plants (which increases plant diversity);
dam could reduce (diversity of) river fish species / cause loss of brook trout species;
dams lead to loss of trees/terrestrial vegetation from flooding (reducing species diversity);
as flooded trees die more nesting sites are provided for birds (increasing species diversity);when flooded trees die it decreases habitat availability for some organisms reducing species diversity;
low levels of oxygen in the resultant pond could reduce fish diversity/aquatic species diversity;
succession in meadow after dams collapse results in greater habitat diversity / when dams collapse, beaver meadows create habitats which differ from the surrounding forest.
Accept other reasonable responses.
Do not accept only “trees die / speciation”.
Responses varied widely with some good answers. A common error was to state only the amount of nutrients or oxygen levels within the pond and not give comparison values. Some candidates incorrectly read the values on the graph or did not give any values at all within their response.
\nThis question was well answered with a significant number of students achieving full marks.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nFigure 4(a): Tavy – traditional method of slash-and-burn agriculture used in Madagascar
\nFigure 4(b): Clearance of forest for traditional tavy method of agriculture
\nFigure 4(c): Agroforestry – an alternative to the traditional tavy method of farming
\nWith reference to Figures 4(a), 4(b) and 4(c), outline two reasons why a change from tavy agriculture to agroforestry may be more sustainable.
\nOutline two reasons why the change from tavy agriculture to agroforestry may be difficult to achieve.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nIn agroforestry:
forests/habitats and their biodiversity are maintained / reduces deforestation;
tree/forest cover/root system reduces risk of flooding/flash floods/soil erosion;
tree canopy/plant cover reduces impact of precipitation on soils / soil erosion;
within agroforestry soil maintains organic matter / levels of fertility / trees fix nitrogen in soil / leaves from trees enrich soil;
forest provides a variety of resources e.g. medicinal plants/firewood/timber/crops / farmer can get milk and food from agroforestry / forest can provide fodder for animal;
manure from animals can be used as a fertilizer for crops/trees;
land can be used sustainably/indefinitely/over long period of time rather than for a few years;
no burning of woodland reduces amount of carbon dioxide effect on global warming/climate change / forest can absorb carbon dioxide.
Accept converse statements for tavy method.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ntavy is a method that can be considered part of the local culture/traditions;
people tend to have an aversion to change / do not trust change;
if site conditions are poor, rehabilitation can take time / if soil is poor in nutrients it can be difficult to establish agroforestry / trees take time to grow so benefits would not be seen immediately;
agroforestry cannot provide same products as traditional methods e.g. rice;
lack of education to explain the advantages of alternative methods / lack of knowledge about agroforestry / agroforestry is a more complex system to farm / tavy is easier than agroforestry /agroforestry requires more work;
lack of funds to promote agroforestry.
\n
The majority of responses were good and a large proportion achieved full marks.
\nThe majority of candidates achieved either 1 or 2 marks for this response. A common error was focusing on only one marking point.
\nFigure 1: Three projections for world population from the present day to 2100. The three lines indicate the high, medium and low projections for population size.
\n[Source: From World Population Prospects: the 2015 Revision, by UN Department of Economic and Social Affairs, Population Division, ©2015 United Nations. Reprinted with the permission of the United Nations.]
\nCalculate the range between the highest and lowest projected population size for 2100.
\nIdentify two factors that could explain the variation in the projected population growth for the world.
\nOutline one economic implication of the highest projection for world population being realised.
\nOutline one environmental implication of the highest projection for world population being realised.
\nOutline one advantage of modelling future human population sizes.
\nOutline one disadvantage of modelling future human population sizes.
\n(16.3 billion − 6.6 billion =) 9.7 billion;
\nAccept 9.5 billion to 10 billion.
\n[1 max]
\nstrict anti-natal policies;
higher level of education for women (reduces number of births/leads to lower population);
disease (can reduce population growth);
war (can reduce population growth);
natural disasters (can reduce population growth);
availability / lack of sufficient resources/water/food (can curtail population growth);
pro-natal policies;
lack of access to contraception/birth control/family planning;
increase access to healthcare;
technology / technological development (that allows sufficient resources/food to meet demand of growing population);
varied basic assumptions;
different modelling methods.
[2 max]
\nlack of sufficient jobs (for increasing number of people) leading to under employment / unemployment;
unemployment leading to greater demand for unemployment insurance/social assistance;
unemployment leading to growth in crime requiring more investment in police force/greater insurance costs;
increase in the number of people in poverty;
increase in workforce contributing to economic development/growth;
greater demand for schools/health care increases cost to government;
greater demand for housing increases economic cost in building;
increasing demand for limited resources will elevate prices.
Accept any other reasonable response.
Do not accept ‘shortage of resources’ without link to economic implication.
[1 max]
\n\n
destruction of protected/marginal areas/clearance of land for agricultural production to feed the larger population/for urban development;
use of marginal lands for agriculture and increased soil degradation;
loss of habitat to land development/farming;
loss of species from loss of habitats/increase in hunting/poaching;
increase in pollution/waste production (from increased numbers of people);
increased extraction of water (for drinking/agriculture) leading to water scarcity/water shortages for other species;
increased need for desalination leading to changes in chemistry in coastal waters.
Accept any other reasonable response.
Do not accept only ‘loss/depletion of (natural) resources’.
[1 max]
\n\n
allows projections to be made for planning purposes (e.g. schools/hospitals);
allows changes to be proposed to policies to slow population growth;
allows policy makers see what impact a policy might have on population;
can help with decisions on resource management to meet the needs of the population;
models are simple to understand.
[1 max]
\n\n
all models are a simplification and therefore incorrect;
the data on which the modelling is based may be unreliable;
the model/computer program used may be imperfect;
human behaviour can change, so that the prediction is not fulfilled;
many factors in the environment can change, making projections uncertain;
it cannot foresee natural disasters or international conflicts;
potential for human error in calculation/tool development/application/interpretation of model.
Do not accept ‘not correct/unreliable’ without explanation.
Do not accept ‘model relies on many factors’ as it is the accuracy of the data used that is important.
[1 max]
\n\n
The majority of responses were correct. A frequent mistake was to incorrectly calculate the range or omit ‘billion’ from the number.
\nGenerally candidates responded well to this question with most achieving either 1 or 2 marks. Common error was to state there was an increase or decrease in birth/death rates without identifying the factor that could cause this change.
\nThere were some excellent responses however a significant number of candidates suggested there would be fewer resources available without linking to an economic change (e.g. increase in price of goods) or the environmental implications of using more natural resources (e.g. deforestation).
\nThere were some excellent responses however a significant number of candidates suggested there would be fewer resources available without linking to an economic change (e.g. increase in price of goods) or the environmental implications of using more natural resources (e.g. deforestation).
\nThe majority of candidates correctly identified an advantage of using population models.
\nMany candidates gave a vague response e.g. the model is inaccurate/imprecise without explaining a reason for this.
\nDistinguish between the concept of a “charismatic” (flagship) species and a keystone species using named examples.
\nExplain the role of two historical influences in shaping the development of the environmental movement.
\nDiscuss the implications of environmental value systems in the protection of tropical biomes.
\nAward 1 mark for two valid examples (one of each kind)
charismatic/flagship eg Panda/Tiger and keystone eg Northern Spotted Owl/Sea Stars/Fig Trees/Sea Otters/Jaguar;
Award 3 max for valid points of distinction:
charismatic/flagship species are used to publicise/advertise conservation campaigns/stimulate public action/raise economic support;
...they are selected because they appeal to humans/have ideological/cultural/religious significance;
their value is primarily subjective/relative to a society rather than ecological;
keystone species have a disproportionately large effect on their environment/may determine structure of an ecosystem/have many other species dependent on them;
keystone species may be publicly unpopular/threat to locals/considered pests/killed for fur/trophy;
they are identified through ecological/scientific/objective study of their relationships with the entire ecosystem;
While it is acceptable to award a mark for stating a discriminatory feature of just one kind of species (without referring to contrasting feature of the other), do not credit directly converse statements twice e.g. “flagship are X ...keystone are not X” would gain only 1 mark if X was valid.
\neg Rachel Carson – Author of Silent Spring (1962);
Silent Spring documented/highlighted the problems caused by the widespread use of synthetic pesticides;
focus was placed on the activities of chemical companies;
explained impact of use of insecticides/pesticides on birds of prey;
led to widespread awareness amongst (American) public of environmental issues/bioaccumulation/biomagnification;
was a focal point for the social/environmental movements of the 1960s;
inspired many other environmentalists;
led to ban on DDT for agricultural uses;
inspired the formation of the U.S. Environmental Protection Agency;
eg Fukushima Daiichi nuclear disaster of 2011;
a natural disaster/earthquake/tsunami led to the biggest nuclear disaster since Chernobyl at Fukushima Nuclear Power Plant;
estimates vary about the number of people affected by the disaster/no direct deaths initially/over 600 deaths by workers/thousands with increased risk of cancers;
as the disaster was able to happen in a “developed” country like Japan, many societies came to the conclusion that nuclear power could not be “safe”;
this has led to increased public pressure to phase out nuclear power generation;
eg Germany sped up plans to close nuclear reactors/over 90 % of Italy voted against government plans to expand nuclear power/Switzerland also decided to phase out nuclear power;
Award [1 max] for correctly identifying/naming two historical influences.
Award credit for valid statements that describe the personality/event; explain how it has influenced the movement; and explain exactly what gave rise to the influence.
If more than two events/personalities are addressed credit only the highest-scoring two.
Award [4 max] for each explanation of how historical influences shaped the development of environmentalism up to max of 7 marks.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nPlease refer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQ5 was the least favourite of the options in Section B and yet the highest scoring. Part (a) was generally very well-answered with clear distinctions given between charismatic and keystone species and valid examples of each.
\nAgain, the majority of candidates provided two valid examples of historical influences along with sufficient detail of their significance in the environmental movement.
\nMost candidates were able to sketch the character of two or three value systems, though these were often rather woolly and were not always applied effectively to the protection of tropical biomes specifically. This resulted in many responses not emerging from the 1-3 markband because there was no real analysis or detailed, relevant examples.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nIdentify one of the criteria that may have been used by the International Union for Conservation of Nature (IUCN) Red List to classify aye-aye as endangered.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nreduction in population size;
population size / low population;
number of mature individuals / number of individuals able to reproduce;
geographical range / area of occupancy (i.e. where species are normally found) / extent of occurrence (boundary line that can be drawn around sites that the species occupies);
reduction in number of locations (the species is found in);
degree of fragmentation (e.g. via road or urban development);
quality of habitat / loss of habitat / habitat degradation;
probability of extinction;
Link must be made to the IUCN factors, as listed above.
\n\n
Only about half the candidates answered this question correctly. Common errors included focusing on 1933 when Aye-aye were incorrectly considered to have been extinct, that Aye-aye are endemic species or the fact that they are hunted.
\nFigure 9(a): Fact file on beaver’s role in the ecosystem
\n© International Baccalaureate Organization 2018
\n\n
Figure 9(b): The succession of ecosystems caused when a beaver dam is built across a river
\nWith reference to Figures 9(a) and 9(b), describe one abiotic change and one biotic change in a beaver meadow community undergoing succession.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nBiotic [1 max]:
increase in small bushes followed by trees / reforestation / plant diversity increases;
increase in (mammal) species more adapted to forests;
increase in animal diversity / increase in predation due to greater animal diversity;
Abiotic [1 max]:
reduction in soil moisture (as water is taken up by trees);
reduction in soil nitrogen / reduction in soil nutrients;
reduction in light penetration;
reduced temperature ranges due to greater shade in day;
increased humidity due to transpiration by trees/water channel/creation of river;
Do not accept only “change in vegetation/creation of new vegetation area”.
Do not accept “increase in water turbidity” as meadow is not a water body.
Very few candidates correctly described changes in two suitable factors. Most candidates described changes linked to a river system that was being dammed rather than a beaver meadow undergoing succession. Some students did not know the difference between biotic and abiotic factors.
\nFigure 6: Fact file on aye-aye (Daubentonia madagascariensis)
\n[Source: © International Baccalaureate Organization 2018]
\nWith reference to Figure 6, evaluate the role of international zoos and wildlife parks in the conservation of aye-aye.
\nAdvantages [2 max]:
zoos provide a safe haven for aye-aye;
they provide an opportunity to research aye-aye biology and behaviour/increase our knowledge;
they can be used to raise awareness/educate the public about the threats to the species/ wildlife in Madagascar;
they can be used to obtain funds to help conservation efforts in Madagascar;
breeding (pairs) can be used to increase the number of aye-aye;
these can be re-introduced into the wild.
Disadvantages [2 max]:
re-introduced individuals can find it difficult to survive in the wild;
it is difficult to recreate suitable/natural habitats for animals in captivity;
it is morally/ethically wrong to keep these primates in captivity;
captive animals can develop health problems / species can become stressed in captivity / experience behavioural problems in captivity;
international zoos/wildlife parks are expensive to create and maintain;
funds from zoos could instead be spent on habitat conservation efforts / funding for zoos detracts funds from habitat conservation;
does not address the causes of reduction in aye-aye population e.g.
deforestation/hunting/cannot stop people killing aye-aye in the wild;
Appraisal/conclusion [1 max] that is balanced and substantiated, for example:
although international zoos provide an opportunity to increase species numbers through breeding programmes, without tackling the issue of habitat protection the species will remain under threat.
Most students achieved 1 or 2 marks by focusing only on the advantages of using zoos and wildlife parks rather than also including disadvantages and giving a balanced appraisal.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nSuggest how an ecologist might measure the changes in one abiotic factor along a transect from a beaver marsh, through beaver meadow to the adjoining forest.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nuse appropriate method/sampling device for identified abiotic factor eg use of thermometer to measure soil or air temperature / pH probe to measure pH value of soil / light sensor to measure light intensity / soil test kits to measure concentration of nutrients/nitrates/phosphates / hygrometer to measure humidity / use of soil moisture sensor/tensiometer / soil texture using different mesh size sieves;
use systematic sampling/interrupted belt transect/ take readings at regular intervals along transect;
repeat readings to obtain averages/increase reliability /take multiple readings to obtain average/increase reliability.
Candidates generally performed poorly on this question and a substantial number did not attempt it. A significant number of responses discussed the measurement of a biotic factor instead of an abiotic factor. Very few candidates included how an abiotic factor could be measured, the importance of taking samples at regular intervals or the value of taking replicate samples or repeated readings.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nExplain why Madagascar has a high number of endemic species.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nisland is too far from the mainland for exchange of genetic information / location of island results in limited migration of species from/to other areas;
geographical isolation has caused speciation / species have developed in isolation/independently / species have adapted/evolved to the conditions on the island;
limited resources on the island required specialization to reduce competition;
climate has been stable for a long time, allowing for specialization of organisms;
there are a diverse range of biomes/ecosystems (providing a diverse range of habitats/niches) / variation in altitude/elevation provides a range of habitats/niches;
tropical rainforests provide many different niches/have high biodiversity;
high biodiversity is associated with larger island size (The Theory of Island Biogeography).
Responses varied widely for this question with many candidates achieving at least one mark. However, few candidates were able to correctly identify 3 factors that led to the high level of endemic species in Madagascar. Many students referred to isolation but did not link this to speciation.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nFigure 7(b): Fact file on beaver hunting
\n[Source: adapted from www.couplesresort.ca, www.ontario.ca, www.sbaa.ca,
www.ecology.info, www.tobyhemenway.com and http://acs7.cortland.edu]
With reference to Figure 7(b), calculate the percentage reduction in the price of beaver pelt between 1940 and 2015.
\nIdentify one reason why the value of beaver pelts has changed over time.
\nAward [1] for working/calculation and [1] for correct answer.
Working/calculation [1]
500 − 19 = 481, then × 100 ;
\n(500 − 19)/500 × 100;
500 -- 100 % then 19 ---- 3.8 % followed by 100 - 3.8;
500 -- 100% then 19 ---- 3.8 % followed by 481 ---- 96.2 %;
500 −19 = 481 then 500 -- 100% followed by 481 ---- 96.2 %;
19/500 = 0.038 then 1− 0.038 = 0.962.
Answer [1]
= 96 / 96.2
\n
This question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nless demand for beaver pelts/fur / people no longer want to wear fur / change in fashion tastes / fur no longer considered beautiful;
changing attitudes towards hunting;
alternative materials available, eg synthetics developed;
glut in market (oversupply) from other areas reducing unit price / large number of beavers in 2015 resulted in cheaper pelts.
Do not accept “almost extinct in 1900” since the two comparative dates are 1940 and 2015.
Do not accept “beavers are considered by IUCN as least concern”.
Do not accept only “there has been an increase in numbers”.
\n
The majority of students correctly conducted this calculation and achieved full marks. A few candidates lost a mark by not showing any workings of the calculation.
\nThere were mixed responses to this question. A common error was not linking the high number of beaver pelts in 2005 to lower prices compared to 1940. Many candidates just referred to beavers nearly becoming extinct in 1900 or its IUCN status.
\nFigure 7: Ecological footprint and biocapacity* per person in Madagascar
\n* biocapacity: amount of biologically productive land, measured in total hectares per person
\nDescribe the trend in the ecological footprint over the period shown in Figure 7.
\nOutline why the ecological footprint for the total population of Madagascar has increased during the period shown in Figure 7.
\nOutline one reason for the trend in biocapacity during the period shown in Figure 7.
\necological footprint has gradually declined / there has been a small reduction/decline in the ecological footprint;
the ecological footprint has declined from 2 hectares per person (in 1961) to about 1 hectare per person (in 2012).
figure 7 only shows individual ecological footprint / EF per person has decreased / individual/personal EF has decreased (not ecological footprint for the total population);
population increased over this period / overall ecological footprint for population increases due to growth in population;
population has increased at a greater rate than decline in individual ecological footprint.
biocapacity has declined over time due to degradation/erosion of soil;
traditional/tavy method of farming results in nutrient poor soil reducing biocapacity/biological productive land;
traditional/tavy method of farming results in soil erosion/degradation reducing biocapacity/biological productive land;
increase in population reduces biocapacity per person/per capita / increase in population reduces global hectares per person/per capita / with increasing population amount of productive land needs to be divided between more people;
increased population has resulted in more land used for houses/urbanisation reducing biocapacity/productive land.
Only about half of responses were correct. Some candidates did not seem to understand what was required and instead of describing the ‘overall trend’ stated each small change over time. Other common errors included suggesting the trend showed no change or an increase in ecological footprint, alternatively some responses focused on changes in biocapacity.
\nFew candidates understood the difference between ecological footprint per capita and ecological footprint for the country. Some recognised the increase in population caused the overall ecological footprint of the country to increase. However, many candidates incorrectly related the differences to industrialisation or decline in biocapacity.
\nMany candidates struggled with explaining why biocapacity declined overtime. Popular responses suggested it was because of tavy agriculture or deforestation but did not suggest how this reduced soil productivity.
\nFigure 2: A graph showing past mass extinctions.
\n[Source: The Earth Through Time, Eighth Edition by Harold L. Levin. John Wiley & Sons. ISBN: 9780471697435. 2006. Chapter 14 Life of the Mesozoic. Graph:Diversity of marine animals through geologic time, as indicated by number of known fossil genera. Used with permission from Wiley. Permission conveyed through Copyright Clearance Center, Inc.]
\nState two possible causes of these past mass extinctions.
\nIdentify two ways in which the current extinction differs from mass extinctions in the past.
\nExplain one factor that may make a species less prone to extinction.
\nOutline how the process of natural selection is a mechanism for evolution.
\nmeteorite/asteroid/comet impacts;
significant volcanic events/volcanic eruptions/basalt flows;
climate change/ice age;
catastrophic methane release (e.g. from methane clathrate);
drop in oxygen levels;
sea level changes;
cosmic events/radiation from space that depletes atmospheric ozone.
Do not accept ‘natural disasters/disease/earthquakes/floods/water levels rising’.
\n[2 max]
\n\n
rate of change is faster/happening over a shorter time frame;
caused by another species changing the environment/not caused by natural phenomena as in the past/caused by humans;
humans can prevent current extinction.
[2 max]
\n\n
reach sexual maturity early;
…which means they are able to produce offspring early/have more offspring/have larger populations (and increase their species chances of success);
they can have high reproductive success/produce large number of offspring;
…large populations can increase the chances of their survival;
they are opportunistic /r species able to adapt to a wide variety of conditions;
…this allows them to be present in many habitats / have wide geographical coverage;
they have fast lifecycles (e.g. r species);
…which allows them to adapt quickly to change;
they have a number of habitats they can shelter/live/ are widely distributed;
...so if a population is affected in one habitat (e.g. by disease/predation) the species will still survive in another habitat/location;
they are omnivores/generalist feeders/switching predators;
...this adaptability to eating different foods results in potentially a large available food source/with some food source available even under harsh conditions;
ability to hide/camouflage/successfully fight;
...which can reduce predation rates and increase chances of species survival;
have high genetic diversity;
...they are able to adapt to changing environmental conditions;
valued by humans (e.g. as keystone/flagship species);
..increases human investment/action into conserving the species/its habitat (e.g. Giant Panda);
not considered valuable by humans (e.g. as pets or making ornaments);
...it is not hunted /removed from habitat thereby reducing risk of extinction.
Award 1 mark for identifying the factor and 1 mark for the explanation.
Accept other reasonable responses.
[2 max]
\norganisms in any population vary;
\nsome traits make them better adapted to survive / selection pressures in the environment may favour some variations over others/‘the survival of the fittest’;
\nthus organisms become adapted to environmental conditions;
\nsome of these variations give it a competitive advantage leading to breeding success / those organisms that survive are able to breed and pass on their traits to their offspring;
\nwhere conditions (e.g. climate) change, the organism may respond by adapting to it;
\nisolation (geographical/ecological/reproductive) may separate a part of a population from others;
\ndifferences in the environments may cause speciation/evolution of new species as the population adapts to the new environment;
\nthe new species may be unable to interbreed with the parent species to produce fertile offspring.
\n[2 max]
\nMost students were able to state two correct reasons.
\nMost candidates were able to identify at least one way in which current extinction is different from past mass extinctions.
\nThis question was answered well by the majority of candidates. Some responses identified a factor but did not give an explanation.
\nResponses to this question varied widely from well-focused answers to those that gave a vague description of evolution.
\nOutline the reasons why natural capital has a dynamic nature.
\nExplain how the inequitable distribution of natural resources can lead to conflict.
\nThe management of a resource can impact the production of solid domestic waste.
\nTo what extent have the three levels of the pollution management model been successfully applied to the management of solid domestic waste?
\nthe value and status of natural capital may vary regionally;
eg cork may be highly valued in areas where grapes for wine are grown;
the value may also vary over time;
eg cork has been used for millennia as bottle stoppers for wine and other products but in the last 20 years its value has decreased as other resources have been used to seal wine bottles;
the value may vary due to other reasons, eg social/political;
eg uranium’s value decreased quickly after the Fukushima nuclear disaster when public pressure led to several countries declaring they would phase out nuclear power;
the value may vary due to environmental/technological reasons;
eg lithium’s value has increased as it is used to make batteries for electric cars and personal devices;
Award [1] for each correct reason and/or example, up to [4 max]. N.B. Credit may be allowed for alternative egs of equivalent validity, detail and relevance.
\nnatural resources like water/food/productive land/fossil fuel/ore deposits are distributed unequally around the globe/some countries have a lot, some others have few;
eg sub-Saharan African countries face water shortages/Middle East countries have a huge surplus of oil;
which may lead one country to invade another for its resources eg ore deposits in Congo/Afghanistan;
inequitabilities may also arise from changes within societies due to over consumption/population growth/lack of technology (agricultural/extraction/mining)/unsustainable development;
…or from changes in their surroundings eg climatic change/international politics/economics/war/embargoes;
eg food price crisis in 2008 causing protests/riots/political/economic/social unrest (in both LEDCs & MEDCs);
eg water scarcity due to climate change in Syria is argued to be a major cause of civil war in 2011;
Inequitability often leads to conflict when a resource is shared across national borders (usually water storages or oil deposits);
eg sharing the Nile’s water resources between Ethiopia, Sudan and Egypt;
inequitability in energy/fuel reserves is particularly significant to economics/national security;
eg leading to, and promulgating many conflicts in the Middle East;
conflicts can also occur between constituencies within a country eg social classes/ethnic groups/resentments over government regulations/bans/taxation/private ownerships v public;
eg when cost of clean water is prohibitive for lower social classes;
Award 1 mark for any argument/valid eg connecting unequal resource distribution to conflict;
Allow 4 max for outlining inequality in resource distribution without clear reference on how it is leading to conflict.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with“Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nPlease refer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nWhere candidates correctly associated the term “dynamic” with the status or economic value of a resource/natural capital, they generally scored well on exemplifying this in their response.
\nAlthough most candidates could recognise the principle being addressed, they generally failed to gain full credit by limiting their response to a single context in which conflict over resources arise, rather than exploring a fuller breadth of contexts to more fully explain the phenomenon.
\nWhile a good proportion of candidates had some notion of the 3-level pollution management model, some struggled to apply this to the management of solid domestic waste. And, many of those that were able to do this failed to go on to evaluate its success with any rigour. Such a lack of analytical skill commonly kept the response out of the 7-9 band and even limited scores within the 4-6 band.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nIdentify one reason why the trapping of beavers is permitted in Algonquin Provincial Park.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nrecognition of rights of First Nations to keep cultural traditions alive / part of cultural heritage of First Nations / food source for indigenous people;
population of beaver are high / populations are able to recover easily;
beavers are categorised as “Least Concern” on IUCN Red List;
hunting only occurs at a very small scale;
value of pelts is so low that trapping will be motivated by cultural influences rather than economic factors;
reduces damage to property/flooding caused by beavers/beavers cause economic damage;
provides income from hunting licences.
Do not accept only “beavers cause damage / trapped by indigenous people / increases tourism / caught only during hunting season”.
\nThis question was answered well by most candidates. However, some candidates inappropriately discussed how beavers were hunted instead of focusing on the reasons.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nIdentify one benefit of the reintroduction of beavers in Europe.
\nIdentify one potential problem with the reintroduction of beavers in Europe.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nbeavers increase diversity of habitats with their dams which increases biodiversity;
opportunities for ecotourism as people can see the beavers;
beavers once lived in this area so this is ecosystem restoration;
additional food source for other species, eg wolves;
possible economic benefits if trapped for pelts;
increased genetic diversity of beaver population / can breed with other beavers and increase beaver population;
to restore wetland habitat.
Do not accept “beavers build dams that regulate water flow”.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nincreased damage to property (through gnawing wood);
flooding when beaver dams collapse / beaver dams can cause flooding;
increased conflicts between landowners and beavers;
upset/unbalance the food webs / outcompete other species / competition with other species;
impact on existing habitats / create short-term changes;
people are not used to them so will not know how to manage them;
poaching is a risk in a region with a high density of human population;
genetics of introduced population may be very different from that of original stock;
may not adapt well to new location and die;
may have no natural predator to limit population.
Do not accept “beavers are an invasive/alien species”.
\nThis question was extremely well answered, with most candidates recognising that beavers are introduced into Europe to restore wetlands.
\nFigure 8(a): Fact file on MaMaBay
\n[Source: © International Baccalaureate Organization 2018]
\nFigure 8(b): MaMaBay including Antongil Bay, north-east Madagascar
\nFigure 8(c): Deforestation hotspots within MaMaBay in 2009
\nWith reference to Figures 8(a), 8(b) and 8(c), suggest two reasons why Makira National Park was created in the area shown.
\nhigh level of biodiversity in the area / park is located in area that contains 50% of the island’s biodiversity / to protect biodiversity;
threat to habitat due to deforestation / is a deforestation hotspot that threatens habitats/biodiversity / as an attempt to reduce deforestation in the area;
provides a corridor to Masoala National Park;
few villages are located there so it is easier (less opposition from locals) to create the National Park there / has limited effects/restrictions on villages surrounding the area;
potential for ecotourism development in the area.
This question was well answered by the majority of candidates.
\nFigure 3: The number of plant species present on the slopes of two volcanoes, which erupted in the 1880s. Measurements were taken in 1930, 1975 and 2015.
\n[Source: Data courtesy of Roger del Moral]
\nState the ecological processes illustrated by the data in Figure 3.
\nDescribe a method for measuring the abundance of plant species in volcanic areas.
\nSuggest two reasons why there are differences in the number of plant species found on Krakatau and Tarawera.
\n(primary) succession / colonisation (of islands)/lithosere.
\nDo not accept ‘secondary succession’.
\n[2 max]
\nselect sample areas representative of the area / select sampling sites using random sampling method / use aerial photographs of the area;
\ndo quadrat/transect based sampling to collect data;
\nrecord the number of individual plants of each species / proportion of cover;
\ncalculate abundance as % frequency / % cover / using ACFOR scale in the quadrats;
\nextrapolate for the whole volcano;
\nrecord during different seasons.
\n[3 max]
\npresence of ash increases plant diversity/different type of volcanic surfaces affects speed of colonization/weather differently;
... ash is plant ready whereas lava has to weather before it can support plants;
...having plants in ash will speed up weathering of adjacent lava;
...ash can be nutrient rich enhancing plant growth/diversity;
...plant roots can more easily penetrate ash than lava surfaces thereby contributing to greater plant diversity;
differences in climate/latitude: one is in tropics and experiences high rainfall/and temperature/insolation / one is in temperate latitudes with lowerrainfall/temperatures/insolation;
...plants in tropical rainforest biome grow rapidly all year / conditions can support a wide range of plant species;
...plants in temperate latitudes/with less insolation/rainfall/lower temperatures grow more slowly /conditions support a narrower range of plant species;
the level of biodiversity from nearby areas that are the source of the colonising species varies;
…there is a high level of biodiversity near Krakatau;
…there is a lower level of biodiversity near Tarawera;
direction of prevailing winds determine from which areas seeds/species are introduced from;
…Krakatau is downwind of areas which are rich in biodiversity;
…Tarawera is downwind of areas which have lower levels of biodiversity;
development of tourism/human activity in one area could reduce the number of species;
...building of infrastructure/roads/houses/amenities could result in removal of some species.
2 max for identifying 2 factors and 2 max for explanation of these factors.
Do not accept ‘volcanic eruption happened earlier in Krakatau’ or difference in latitude/climate without specifying which factors e.g. higher rainfall.
[4 max]
\nA significant proportion of candidates did give the correct response. A common mistake was to state volcanic eruption or zonation as the process.
\nMost candidates achieved some marks for this question, with many correctly suggesting the use of random sampling strategy and quadrats. Many answers incorrectly included Lincoln Index or Simpson Diversity Index and confused determining abundance of species with species diversity.
\nMarks varied widely between 0 and 4 for this question. Some responses were too vague e.g. referred to climate without linking how higher/lower levels of sunlight/rainfall/temperature would affect plant diversity at each specific location.
\nOutline how soil can be viewed as an ecosystem.
\nCompare and contrast the impact of humans on the carbon and nitrogen cycles.
\nDiscuss the role of humans in the destabilization of ecological systems.
\nLike an ecosystem, soil is an open system with inputs and outputs;
(inputs of) eg water/O2 (and outputs of) eg CO2/nitrogen;
...and storages and flows/processes;
(storages of) eg nitrates/water (and flows of) eg leaching/decomposition;
like an ecosystem, soil is a community of living/biotic and abiotic elements;
(biotic) eg bacteria/fungi/earthworms (and abiotic) eg clay/sand/silt/water/heat;
...with the many complex interactions/interrelationships/eg mineral cycling/leguminous plants;
interacts with/supports other systems/eg vegetation growth, animal movement/burrowing/human development;
Award marks as above for identifying relevant common features, and also for giving examples (provided it is clear what is being exemplified).
\nin both cycles combustion (of forests/fossil fuels) increases concentration of oxides in atmosphere;
in both cycles deforestation/agriculture/SDW lead to decomposition that also releases oxides;
...but carbon dioxide released (by respiration) into atmosphere/(whereas) nitrous oxides are released into soil water (by nitrification);
both oxides will increase impact of global warming/climate change;
...but NOx to a smaller degree;
both oxides result in the acidification of water/aquatic bodies;
...but only NOx may cause acid deposition/acidify soils;
deforestation removes organic storages of both N and C (stored in plant biomass);
…and reduces absorption of C from atmosphere (via photosynthesis) (but not N);
…causes soil erosion which reduces inorganic N storages in soil (but not C);
use of inorganic fertilisers increases N in soil (but not C);
…and run-off may cause excessive inorganic N in aquatic systems (but not C);
pesticide/herbicide use in agriculture might kill organisms thus reducing both C and N organic storages (stored in their biomass);
… thus reducing nitrification/denitrification/decomposition process/(whereas) effect on C cycle is limited to reducing respiration by soil animals;
extraction of oil/coal/gas reduces underground (ancient) C storages/transfers C storages on surface (for human use)/(whereas) effect to N cycle is limited to a few organic compounds/aromatics found in oil;
Award 5 max if only similarities or only differences are identified.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nQ7 was the second most popular option in Section B. Most candidates could identify some key features of a system or ecosystem and exemplify them within soil, but few identified sufficient for full credit.
\nA good majority of candidates had some knowledge of C and N cycles but few could identify human impacts on these much beyond the burning of fossil fuels to increase atmospheric storage of carbon.
\nThe most successful responses to this question demonstrated a sound grasp of the principles of ecological stability and the concepts of resilience and tipping points and were able to develop a strong line of analysis and argument. However, the majority of candidates simply catalogued a range of human impacts limiting their scores to the lower markbands. This raises an issue of question selection. With a “Discuss” command term a candidate needs to be confident of producing a balanced argument and analysis to gain full credit, and not simply a long list of relevant knowledge statements.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nFigure 7(a): Fact file on North American beavers
\n[Source: adapted from www.sbaa.ca, www.ecology.info, www.tobyhemenway.com and http://acs7.cortland.edu]
\nFigure 10(b): Algonquin wolf pack territories and protected areas
\nWith reference to Figure 7(a), outline one reason why there are more beaver remains in wolf faeces during summer.
\nThe number of wolves in Algonquin Provincial Park is estimated to be between 250 and 1000. Outline two reasons why it is so difficult to estimate the number of wolves accurately.
\nWith reference to Figure 10(b), explain the threats to the future existence of a small and sustainable population of wolves as a result of their protection in limited area.
\nbeavers remain in lodges in winter so they are unavailable as a food source / harder for wolves to catch them / easier to spot beavers in summer when they are out of their lodges;
other species (eg moose) are easier to catch in winter;
other prey of wolves like snowshoe hare or foxes may be harder to catch in summer;
young are out in summer and are more vulnerable/easily caught;
density of population higher in summer following breeding.
Do not accept only “beavers breed in the summer” or “beavers remain in lodges in winter”.
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nremote wilderness areas so hard for scientists to spot them easily / densely wooded so not easily visible from the air;
large territorial range (35 km2)/highly mobile so hard to locate;
wolves are nocturnal/hunt at night/sleep during the day and therefore difficult to spot;
look very similar to coyotes so hard to identify accurately;
lack of long-term records to use as baseline data;
camouflaged so hard to see especially in winter;
seasonal fluctuations in numbers.
Do not accept “wolves are dangerous/predators/migrate”.
Do not accept “wolves are mobile so use of quadrat method is not effective” or “use of capture, mark, release, recapture method is not suitable (as it may harm the wolves)”.
Do not accept only “wolves look similar to coyotes / have large territorial range”.
This question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nif the range overlaps with areas outside of Algonquin Provincial Park, ie not protected, the wolf is at risk of being hunted / may be mistaken as coyotes in the buffer zone and killed by accident;
genetic isolation may occur as there may be no mixing with wolf populations from outside of Algonquin Provincial Park;
restricted gene pool can lead to less resistance to diseases;
high population density increases risk of diseases spreading;
wolves may end up competing for territory/food with each other leading to higher mortality/limiting population growth / increase in intraspecific competition;
concentrated population is more prone to high losses during event of wildfires/natural disasters.
Many candidates gave responses that were too vague to be credited. For example, a common error was not to link beavers remaining in lodges to reduced predation by wolves during the winter.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nExplain how the protection of forests in Makira National Park may contribute to the conservation of the aquatic environment of MaMaBay.
\npreserving forests reduces soil erosion / tree roots hold soil / protecting tree canopy reduces impact of rainfall on soil erosion;
forests reduce sedimentation into the bay;
sediment can smother organisms living in the bay;
suspended solids in the bay can reduce light penetration and result in reduction of photosynthesis/loss of plant species;
protection of forest could reduce agricultural activity/urban development that contributes to nutrient pollution/runoff;
run-off/effluents containing nutrients can lead to eutrophication/algal blooms in the bay;
eutrophication/algal blooms could cause anoxic conditions/cause death of fish/reduce biodiversity within the bay;
protection of forest increases carbon sink, which mitigates global warming and reduces warming oceans/ocean acidification which could negatively impact the bay (e.g. loss of coral reefs/loss of fish diversity);
protection of forest increases tourism that generates funds that can be used for conservation of the bay/coast;
protection of forest prevents development of industry that would otherwise release effluents into the bay.
Few candidates answered this question well. A significant number of candidates did not understand the link between the forests, as a catchment area to the bay. Many students repeated information from the booklet rather than applying their knowledge from the ESS syllabus to this scenario.
\nThe resource booklet provides information on Algonquin Provincial Park in Canada. Use the resource booklet and your own studies to answer the following.
\nTo what extent does Algonquin Provincial Park provide a model of sustainable management of a protected area?
\nThis question requires “Resource Booklet - Nov 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nWays in which Algonquin IS a model of sustainable management [4 marks max]:
multiple nature reserve zones that protect different ecosystems/landscapes and species for future generations (environmental sustainability);
Algonquin Provincial Park is a large area (7630 km2) allowing for greater biodiversity (environmental sustainability);
high level of biodiversity makes the area more resilient to change;
(low-impact) recreational uses are allowed accounting for the recreational needs of humans (social sustainability);
indigenous people are still allowed to trap in the park so First Nation rights have been respected (social sustainability);
trapping of beavers is allowed but only on a very small scale / only with ethical traps /hunting of beavers is controlled;
managing beaver population limits damage/flooding of other habitats;
hunting of wolves is prohibited;
park generates an income (economic sustainability) which can be reinvested in managing the park / used for further conservation measures;
no humans are allowed to live in the park to ensure that conflicts are avoided/minimised;
visitor centres are provided in a small part of the park reducing impact elsewhere;
visitor centres contribute to educating people about the park/conservation;
single access point to the park so visitor numbers can be controlled;
campsites are kept simple in wilderness areas so will not have a big impact on most wild areas;
one million visitors a year but still has very high rates of diversity suggesting they are doing a good job of managing it sustainably;
buffer zone around the park protects coyotes and wolves if they stray beyond the boundary.
Ways in which Algonquin IS NOT a model of sustainable management [4 marks max]:
trapping of beavers is still permitted and many people believe that animals should not be harmed (biorights);
boundary of park does not correspond with territorial ranges of wolves so once wolves step outside the buffer zone they may still be hunted or trapped by accident;
nature reserve is only 7% of the area so potentially damaging economic activity is still allowed in 78% of the park;
logging results in habitat destruction (hence conflicts with protection);
natural reserves are fragmented meaning populations might be isolated genetically;
major routeway (route 60) passes through the park so vehicles could hit and kill animals as they cross / roads fragment habitat / roads create a barrier for wildlife movement;
poaching is difficult to control as surrounding roads (Highways 17 and 11) increase access to more remote areas of park;
one million visitors a year is likely to have a big impact as it may be hard to enforce good behaviours, eg not littering, in remote parts of the park / recreational activities may still disrupt wildlife;
development zone is connected to a wilderness zone, so wilderness zone is likely to have heavy use;
development zone is located within wolf pack territory.
Conclusion/Appraisal [1]
For example:
Despite the number of protected areas within the park, the large number of visitors is likely to have an overall detrimental effect on its habitats and associated wildlife and therefore this park is not an ideal model of sustainable development;
Algonquin Provincial Park provides an excellent model of sustainable management by balancing the recreational/social/cultural needs of people (including the First Nation) whilst preserving the biodiversity of the area.
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument) and supported by evidence. Do not credit the conclusion if only one side of the argument has been considered within the overall response.
\nAward 5 max if there is no conclusion/opinion.
Accept other reasonable responses supported by information in the resource booklet.
Do not accept 'protected designation prevents industrial/agricultural/urban development of area'.
Although most students achieved some marks for this question, few achieved full marks. Many candidates did not include both sides of the argument or a balanced conclusion. A significant number of candidates did not attempt this question or just copied out the information from Figures 1b and 2a.
\nFigure 4: The gross and net productivity at different trophic levels within the Silver Springs, Florida, ecosystem.
\n[Source: Kimball's Biology Pages © John W. Kimball, distributed under a Creative Commons Attribution 3.0 Unported (CC BY 3.0) license]
\nState the process represented in the box labelled X.
\nDefine net primary productivity.
\nDescribe how the second law of thermodynamics operates in relation to the transfer of energy within the Silver Springs ecosystem.
\nDistinguish between a pyramid of numbers and a pyramid of productivity.
\nrespiration
\n[1 max]
\nthe gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R).
\n[1 max]
\nthe 2nd law of thermodynamics has energy becoming dispersed, in the ecosystem /overtime there is an increase in entropy;
\nlight energy is converted to chemical energy in plants, with some energy being dispersed in less useful forms /with an increase in entropy;
\nthe chemical energy is passed down the food chain through eating/consumption;
\nthe energy is used in respiration which releases some of the energy (in a less useful form) as heat which increases disorder of the system/increases entropy of the system;
\n90% of energy is lost as heat with each transfer;
\nthe heat goes back to the atmosphere but is removed/lost from the ecosystem.
\nAccept answers which correctly apply the concepts of entropy / energy/heat sources and sinks.
\n[2 max]
\npyramids of numbers display the number of organisms at each trophic level;
...whereas pyramids of productivity refer to the flow of energy through a trophic level (measured in gm/m2/yr or J/m2/yr);
pyramids of numbers can sometimes display different patterns / e.g. an inverted pyramid when individuals at lower trophic levels are relatively large (e.g. oak tree to aphids to blue tits to sparrow hawk);
...whereas a pyramid of productivity always shows a decrease along the food chain;
the data for pyramids of numbers are relatively easier to collect than for pyramids of productivity
...whereas pyramid of productivity requires rate of biomass production overtime which is more difficult to collect;
pyramid of productivity shows the flow of energy overtime.
\nBOTH pyramid of numbers and pyramid of productivity must be addressed to achieve maximum 2 marks.
\n[2 max]
\nMost candidate correctly responded to this question.
\nFew students gave a comprehensive definition of net primary productivity. E.g. ‘per unit area per unit time’ was frequently omitted.
\nMost candidates demonstrated limited understanding of the second law of thermodynamics and responses lacked sufficient detail e.g. marks were lost for not explaining how energy was lost through the trophic levels.
\nIn general this question was well answered by most candidates.
\nFigures 1(a) and 1(b) show the availability of renewable freshwater per capita in 2013 and its predicted availability in 2040.
\nFigure 1(a): Water stress by country in 2013
\nFigure 1(b): Predicted water stress by country in 2040
\n[Source: Maps adapted from www.wri.org. File licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)]
\nFigure 2: Relationship between vegetation cover and evaporation
from different soil types
© International Baccalaureate Organization 2018
\nUsing Figures 1(a) and 1(b):
\nState one country with no expected change in water stress between 2013 and the 2040 prediction.
\nState one difference in water scarcity between 2013 and the 2040 prediction.
\nOutline how climate change may affect the availability of freshwater resources.
\nDescribe two water management strategies that can reduce water scarcity.
\nDescribe the overall trend for sandy soil shown in Figure 2.
\nCalculate the change in evaporation from clay soil when the vegetation cover changes from 50% to 100%.
\nOutline two reasons why loam soils are the most productive for plant growth.
\nCanada/Argentina/Russia/Saudi Arabia/Australia/Mexico/Brazil/India/UK.
\nNote: Do not credit names from Fig1(a), e.g. Europe/Australasia, as these are not country names. Credit may be given for valid countries not labelled in Fig 1(b) e.g. Peru/Libya/Sri Lanka.
\nincreased water scarcity in eg USA/France/Namibia/Spain/China;
increased water scarcity in some countries in sub-Saharan/southern countries in Africa/Middle East;
decreased water scarcity in eg Venezuela/Japan.
Note: a single named country OR a named region AND the difference (increase/decrease) is required for [1] mark. Credit reference to countries not named in Fig1(b), as long as difference is clearly identified.
\nincreased temperatures/evaporation may lead to increased loss of soil water/aridity/desertification;
increased temperatures/evaporation may cause loss/salination of water supplies lakes etc;
changes in precipitation/increased frequency of El Nino events may lead to increase/decrease of water supply/droughts;
rising sea levels may lead to inundation/salination of ground water;
increased temperatures may cause melting of glaciers/ice caps leading to increase/decrease of water availability (i.e. by increased input to lakes/run-off to oceans).
Note: to gain credit, each statement should clearly identify the \"climate change\" element (e.g. increased temperature / decreased precipitation / sea level rise / increased monsoons/typhoons/hurricanes / higher frequency of El Nino / increased evaporation), AND its effect to freshwater resources (e.g. increased supply by melting ice sheets of mountaintops / reduced stream discharge / reduced amount of water in lakes / increased soil aridity / increased salinity / increased or decreased groundwater supply).
\ndesalinisation to increase available supply;
use of water-saving agricultural strategies eg drip irrigation/terracing;
aqueducts/pipelines to move water from water-rich to water-scarce areas;
education/campaigns/increased charges so citizens use less water;
reduce production of crops with high water demand e.g. meat/dairy/almonds/cotton;
use of technology to collect/recycle/reuse water e.g. dams/rainwater/grey-water;
clean-up/restoration of polluted freshwater bodies/lakes/aquifers.
Note: Alternative valid responses may be credited but to gain credit they must identify appropriate strategy and at least indicate its relevance in addressing water scarcity as in MPs above.
\nOnly credit valid “management” strategies as opposed to personal behaviour choices eg taking short showers/turning taps off.
\nas amount/% of vegetation increases the amount of evaporation from soil declines / negative correlation between evaporation and vegetation cover.
\n20 − 5 = 15; Allow 14−16
\nNote: Response needs to show calculation to gain credit.
\nbecause it is a good balance of sand and clay avoiding each of their more negative qualities;
not prone to waterlogging / has good drainage (compared to clay);
allows easy root penetration / workability (compared to clay);
allows good aeration / oxygen supply to roots (compared to clay);
stable / not prone to wind erosion (compared to sand);
retains moisture (compared to sand);
retains nutrients/minerals (compared to sand).
Vast majority of candidates could identify a country with no expected change.
\nCandidates generally identified a specific change in a given country or region but some made statements that were too broad for validity e.g. “water scarcity will increase”.
\nMost candidates could identify one impact of climate change on water availability, although, again, a number made statements that were too vague for credit.
\nMany were able to describe appropriate strategies, but it was quite common for candidates to offer glib responses like ‘turn taps off after use’ or ‘take shorter showers’ that could not be credited as “management strategies”.
\nMost candidates could clearly identify the trend shown.
\nOnly a minority of candidates failed to complete this calculation correctly but, given its simplicity, the minority was quite sizable. Some lost credit for not showing their working which is required by this command term.
\nCandidates grasp of the nature of loam soils proved generally strong in addressing this question.
\nFigure 1 shows the process of carbon capture and storage (CCS) that can be used to manage climate change. Carbon dioxide (CO2) is pumped into three different underground locations, where it is stored.
\nFlow 1 pumps CO2 into an underground saline reservoir.
Flow 2 pumps CO2 into an oil reservoir; CO2 replaces oil; oil is produced.
Flow 3 pumps CO2 into a coal seam; CO2 replaces methane (CH4); methane is produced.
Figure 1: Carbon capture and storage flow chart
\n[Source: Adapted from http://www.wri.org/resources/charts-graphs/carbon-capture-sequestration-flow-chart.
Licensed under CC BY 4.0 International https://creativecommons.org/licenses/by/4.0/]
Outline the evidence that CO2 acts as a greenhouse gas.
\nState a greenhouse gas other than CO2.
\nOutline how the mitigation strategy shown in Figure 1 is different to an adaptation strategy for managing climate change.
\nIdentify two mitigation strategies to manage climate change, other than carbon capture and storage.
\nOutline how Flows 1 and 2 shown in Figure 1 may contribute to the capture and storage of atmospheric carbon.
\nCO2 absorbs (outgoing) longwave/IR radiation/heat elevating global temperatures.
\nAccept references to climate / CO2 data as causal link, eg increase in global CO2 levels correlate with rises in global temperatures.
\nmethane / water vapour / nitrous oxide / tropospheric ozone / CFCs / HCFCs / HFCs.
\nNB if candidate names more than one gas only the first one should be assessed (even if the first is wrong and a later one is correct).
\nthe mitigation strategy reduces the cause of climate change by removing CO2/greenhouse gas from atmosphere;
whereas an adaptation strategy reduces negative/maximises positive impacts of climate change / addresses impacts rather than causes of climate change.
Responses may involve giving examples of either mitigation or adaptation strategies, but to gain the [2 max] they must include the characteristic/distinguishing feature of both mitigation and adaptation (ie “reducing cause” and “addressing impacts”, respectively).
\nreducing energy/fossil fuel consumption through carbon tax/cap & trade;
reducing emissions of NOx/methane/through catalytic converters/regulations;
alternative energy sources;
geoengineering;
fertilizing oceans;
afforestation/biomass production.
Award [1] for each correct answer that will reduce emission/concentration of GHGs in atmosphere, up to [2 max].
\n(both) flows remove CO2 released by smokestacks/power plants/fossil fuel combustion / store waste CO2 underground/beneath impermeable rock/in saline/oil reservoirs;
however, Flow 2 is associated with extraction of fossil fuels that will release more CO2 (on combustion).
Award [1] for each correct answer, up to [2 max].
\nUnfortunately, many candidates interpreted this question as being more complex than it was, searching for evidence within the data on CCS, rather than simply stating an example of evidence required.
\nVast majority of candidates were able to identify another valid greenhouse gas.
\nProbably around half the candidates had a tentative grasp of the distinction between mitigation and adaptation strategies, though not always sufficiently explicit for full credit. There was a significant proportion of candidates erroneously suggesting the difference lay in the fact that adaptation was about changes in lifestyle while mitigation was about technology … whereas both strategies can be addressed through either lifestyle or technological changes.
\nGreat majority of candidates could identify a couple of valid mitigation strategies.
\nThe majority were able to identify that both these flows trapped CO2 underground that would otherwise enter the atmosphere. A minority recognised that Flow 2 was more limited in this respect since it led to the generation of oil that on combustion would release further CO2.
\nFigure 9(c): Tourism multiplier effect
\nOutline how the model shown in Figure 9(c) demonstrates positive feedback.
\nIllustration of positive feedback using figure 9c e.g.:
increase in international tourists generates more wealth for developing tourist industry;
more developed industry/better accommodation attracts more visitors.
Accept other reasonable responses where figure 9c is used to illustrate positive feedback.
\nResponses varied widely for this question. Many did not relate their answer to the information in figure 9c and gave a generic response about positive feedback. Some students misunderstood the term positive feedback and thought it meant a ‘good’ thing.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nOutline one advantage of increased tourism on wildlife conservation.
\nOutline one disadvantage of increased tourism on wildlife conservation.
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nincreased revenues to invest back into conservation;
raises awareness leading to greater support/public engagement with wildlife conservation;
consideration of wildlife as an asset that needs to be looked after;
if local population have jobs in the tourism industry they are less likely to engage in unsustainable tavy farming/fishing activities.
This question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ngrowth in tourist sites/hotels could cause loss of habitats/forests;
creation of roads that fragment habitats;
noise from tourism that disrupt wildlife/mating / disturbances caused by tourists can alter animal behaviour;
litter that can degrade environment / harm wildlife;
increased tourism puts greater demand on limited freshwater that is unsustainable / increase demand for limited water resources that competes with wildlife;
greater access to wildlife areas that could lead to increased poaching/illegal fishing/increase capture for illegal pet trade;
increase in tourism could increase demand of goods/services that cause deforestation/use unsustainable resources (e.g. fossil fuels);
animals/wildlife used as a tourist attraction maybe inappropriately/unethically treated / focus on popular tourist sites may leave less visited sites with fewer conservation resources/funds.
Most candidates answered this question well. Errors included not linking income from tourism to wildlife conservation or not linking raising awareness to increased support or engagement with wildlife conservation.
\nA significant number of candidates gave an answer that was too vague to be credited e.g. using generic terms such as ‘pollution/emissions’ or ‘impacts/effects’.
\nThe resource booklet provides information on Madagascar. Use the resource booklet and your own studies to answer the following.
\nTo what extent could development away from traditional lifestyles lead to greater sustainability in Madagascar?
\nThis question requires “Resource Booklet - May 2018 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nArgument for development away from traditional lifestyles [4 max]:
reduction in tavy agriculture would reduce deforestation/carbon dioxide emissions/soil erosion/soil degradation / tavy is unsustainable because it results in loss of trees/carbon dioxide emissions/soil erosion/soil degradation / increase in alternative practices e.g. agroforestry could increase sustainability by reducing soil degradation/reducing soil erosion/increasing carbon sink;
increase in tourism services could increase investment in conservation / establishing more national parks (to increase tourism) would limit deforestation/protect wildlife;
increase in service industry could reduce dependency on agriculture e.g. tavy;
increase education opportunities lead to better environmental awareness;
increased use of family planning/smaller family sizes could reduce population growth and potentially in the long term lower Madagascar’s ecological footprint;
migration from rural areas will reduce impact in these areas;
traditional beliefs that aye-aye are evil/bring bad luck/pests and should be killed could negatively impact their population/increase their risk of extinction;
alternative energy sources such as solar/wind power could be more sustainable than the traditional use of charcoal / use of renewable energy does not deplete resources (e.g. wood/fossil fuels)/produces lower emissions of carbon dioxide/greenhouse gases.
Against [4 max]:
use of alternative farming methods such as intensive farming could lead to soil degradation/loss of nutrients from soil/increase in runoff containing pesticides/nutrients damaging habitats;
migration to/growth of urban/tourist centres could increase deforestation to build more housing;
development of tourist resort/urbanisation could increase loss of mangrove forest/increase edge effect;
migration to/growth of urban/tourist centres could increase water stress in those areas;
migration to/growth of urban/tourist centres could increase discharges of sewage effluent that have a negative impact in those areas / sewage waste from tourism could damage reef systems/cause eutrophication within aquatic systems;
urbanization/growth of tourist centres could reduce biocapacity/amount of productiveland;
increase in tourism/urbanisation could lead to more roads that damage/fragment habitats;
tourism could increase damage to coral reefs through boat anchors/trampling;
country does not have systems in place to manage higher levels of solid domestic waste production from tourism / increased littering/waste disposal from tourism could damage habitats/species;
ecological footprint has stayed relatively stable (since 1961);
change in lifestyle is likely to increase consumerism/ecological footprint;
it would take time for land/forest that has been degraded (e.g. through tavy) to become suitable for agroforestry;
food production may become less localized/more intensive;
fewer farmers could lead to dependency on importation of food.
Award [5 max] for arguments for and against.
\nConclusion [1 mark] e.g.:
change to agroforestry is likely to increase sustainability but it is not so clear that ecotourism will.
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument) and supported by evidence.
Accept other reasonable responses that link changes in lifestyle to sustainability.
Responses varied widely from 0 to 6 marks. Many responses only focused on changes in agriculture practice from tavy to agroforestry and did not develop other potential changes eg move to tourism or increase in urbanisation. Some answers only focused on economic sustainability and did not consider environmental sustainability. Many accounts also lacked a counter argument to a change in lifestyle or a balanced conclusion.
\nFigure 6: The effects of organic pollution (raw sewage discharged from a pipe) on a stream ecosystem.
\n[Source: Dr. Mel Zimmerman, Professor of Biology and Director of Clean Water Institute at Lycoming College. Adapted from Bartsch and Ingram (1975) ]
\nDefine biochemical oxygen demand (BOD).
\nOutline how turbidity changes after the raw sewage discharge point in Graph B.
\nSuggest how the population growth curve for algae in Graph C would appear if the pollutant had been nitrates and phosphates from fertilizer run-off.
\nOutline why point source pollution is often easier to manage than non-point source pollution.
\na measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity.
\nOWTTE.
\n[1 max]
\nafter the point of sewage discharge the turbidity levels rise until about 150m (accept 125-175m) downstream where levels peak/plateau and thereafter steadily decline;
\nturbidity will increase at the point sewage enters the water, as the pollutant is particulate/coloured;
\nturbidity will increase after the outlet of sewage as bacteria grow rapidly as they consume/decompose the sewage;
\nturbidity remains high as algae now rapidly grow as there are nutrients from the sewage decomposition available;
\nturbidity decreases once the nutrients levels fall to the pre-sewage levels and the algae growth declines;
\nturbidity increases as algae decrease, and then decrease as algae increase.
\nAward 1 max for a clear description of change in turbidity levels along the stream.
\n[2 max]
\nincrease in nutrients will lead to rapid algae growth /could cause algal bloom;
\nalgae levels will decline as nutrient levels become more restricted downstream from the source;
\nalgae would look like the microorganisms curve in the diagram/ rapidly go up right after the pollution outlet;
\nalgae would also decline, like the microbe curve, as the nutrients run out and algae start to die;
\nmicrobes would grow and they could shade out the light for algae causing a further drop in the curve;
\nthe trend observed would be opposite to the current growth curve for algae (on graph C).
\nOnly credit responses that refer to algae levels in Graph C, do not credit descriptions of eutrophication.
\n[3 max]
\npoint source can be clearly identified;
\nso pollution can be more easily monitored;
\nsolutions should be more easily applied / pollution can be stopped directly;
\nwith non-point pollution, source is widespread/dispersed and difficult to identify;
\nsolutions also have to be widespread/dispersed, so there are increased costs/difficulties of monitoring;
\ncompliance is difficult to ensure with non-point pollution because of widespread/dispersed nature of sources.
\n[2 max]
\nVery few students were able to provide a comprehensive definition of biochemical oxygen demand.
\nMost students achieved a mark for describing changes in turbidity level along the stream. Few candidates were able to explain the cause of turbidity or give reasons for the changing levels.
\nMost candidates achieved some marks for this question but few achieved the full 3 marks. Many responses overly discussed eutrophication without reference to the curve.
\nThis question was answered well by most students.
\nThe resource booklet provides information on Iceland. Use the resource booklet and your own studies to answer the following.
\nState one biome found in Iceland.
\nThis question requires “Resource Booklet - Nov 2017 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\ntundra/arctic tundra/taiga/boreal forest/birch forest/coniferous forest;
\nDo not accept only ‘forests/temperate forest/woodlands/ice caps/ glaciers/mountains’.
\nA significant proportion of candidates gave tundra as a correct response. Common error was to suggest ice caps or mountains as a biome or to give a response that was too generalised eg forests.
\nSoil quality is important for global food production systems.
\nFigure 2(a): Soil texture triangle
\n[Source: Courtesy of USDA]
\nFigure 2(b): Horizons (layers) in a typical soil profile
\n[Source: Wilsonbiggs - derived work from File:SOIL PROFILE.png by Hridith Sudev Nambiar at English Wikipedia. Licensed under CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/deed.en)]
\nState the soil texture that has the following composition: 20 % clay; 55 % silt; 25 % sand.
\nDescribe how the addition of sand to a silty clay loam could alter its characteristics for healthy plant growth.
\nDraw a flow diagram to show the flows of leaching and decomposition associated with the mineral storage in the “A” horizon in Figure 2(b).
\nIdentify one other input to the mineral storage in the “A” horizon in Figure 2(b).
\nIdentify one other output from the mineral storage in the “A” horizon in Figure 2(b).
\nOutline why leaving arable farmland fallow (unused) between growing seasons could lead to soil degradation.
\nsilt loam
\nNB if candidate names more than one soil type, examiners should only assess the first one listed (even if the first is wrong and a later one is correct).
\nPositive effects:
it will increase drainage / prevent water-logging;
it will increase infiltration/permeability / reduce loss of water through run-off;
it will increase porosity/air spaces/reduce soil compaction providing more O2 to roots;
it would allow for increase flow/availability of nutrients;
it will promote detritivore/decomposer/mycorrhizal/microbial communities;
it will allow for easier root penetration.
Negative effects:
it will reduce water-holding capacity so less water for plants;
it will increase possibility of leaching, reducing minerals for plants;
it will reduce stability of soil giving less anchorage to plants.
Award [1] for each correct answer, up to [2 max].
Although question implies positive effects on soil, credit can be given for negative effects as long as candidates make this clear as in MPs given above.
Award [1] for each correctly labelled flow with arrows in the right direction.
\nleaching/mineral flow/eluviation through from O horizon;
nitrogen fixation (ie of N diffusing in from atmosphere);
addition of inorganic/nitrate/phosphate fertilizer;
capillary flow up from B horizon;
Do not credit use of simply “fertilizers” or organic fertilizer/compost etc as this would be an input from decomposition. Do not credit “water” as an input.
\nuptake of minerals by plants;
soil erosion;
denitrification;
human activities of mining/soil extraction;
immobilization/microbial conversion of inorganic to organic.
Do not credit cropping/deforestation (as in themselves they are a loss of biomass, not mineral storage). Do not credit drainage/percolation (synonymous with leaching).
Award [1] for correct answer, up to [1 max].
roots no longer hold soil in place/stabilize soil;
soil surface uncovered/more exposed to wind/water erosion;
uninterrupted rainfall/percolation will increase leaching of minerals;
greater evaporation may lead to salinization;
reduction/change in soil fauna/microbes;
lack of veg cover may lead to greater evaporation/drying out of soil.
Award [1] for each correct answer, up to [2 max].
\nA great majority could apply the soil texture triangle to identify a soil type.
\nMajority of candidates could identify at least one relevant impact of adding sand …incorrect responses were generally due to being too vague e.g. “make it better for plant growth/more like loam”.
\nMajority of candidates produced very confused, erroneous or ambiguous responses. All the question required was one storage/box labelled “minerals in A horizon” and two flows/arrows labelled respectively “leaching” and “decomposition” connecting to that box. Whereas, responses included sketches of soil profiles, unattached/unlabelled arrows, paragraphs of text, sequences of soil activities etc.
\nAgain, probably due to candidate’s ambiguous perception of the storage identified, this question produced mostly invalid responses.
\nA good proportion of candidates were able to score at least one of the available marks but often responses were too vague e.g. identifying “soil erosion” “loss of nutrients” but not outlining “why” these were connected to disuse.
\nFigure 6(b): Total annual sulphur dioxide and particulate emissions from smelting factories in Norilsk
\nThe significant increase in emissions in the early 1980s is related to the opening of the third smelter, Nadezhda, in 1979.
\n[Source: Nyland, K., Shiklomanov, N. & Streletskiy, D., 2017. Climatic- and anthropogenic-induced land cover change around Norilsk, Russia. Polar Geography, 40:4, 257–272, DOI: 10.1080/1088937X.2017.1370503.]
\nFigure 6(c): Vegetation damage associated with smelting factories in Norilsk
\n[Source: Adapted from AMAP, 2007. Vegetation damage zones around Norilsk. [online] Available at: https://www.amap.no/documents/doc/vegetation-damage-zones-around-norilsk/647 [accessed 26 February 2019].]
\nWith reference to Figure 6(b), identify one strategy that might have been used to achieve the trend in sulphur dioxide emissions since the early 1980s.
\nExplain the distribution of vegetation damage shown in Figure 6(c).
\nintroduction of scrubbers / use of pollution reduction equipment / reduced use of smelters / cleaner energy source / stricter legislation on emissions / use of a lower-sulphur ore/coal;
\nDo not accept ‘opening of third/new smelter’.
Do not accept ‘closure of smelters / control/limit number of smelters’.
Do not accept ‘only reduction in mining activity’.
Do not accept use of ‘catalytic converters’.
Do not accept only ‘a reduction in use of fossil fuels’.
prevailing/NW winds carry pollutants / winds drive acid deposition/particulates towards SE;
dilution effect of pollutants by wind / concentration of particulates declines with distance away from the source;
acid deposition declines with distance away from the source / acid deposition is greatest near the source of pollution;
higher concentration of pollutants corresponds to a greater level of damage;
transport/deposition rates dependent on nature of particulates;
different pollutants produce different damaging effects;
wind is funnelled along valleys (indicated by lakes)…;
…therefore pollutants carried along valleys…;
water in rivers/lakes spreads the pollutants;
Do not credit descriptions of the vegetation damage.
\nMany candidates incorrectly answered this question. Some candidates did not consider the overall trend since the 1980s through to 2015 as illustrated within Figure 6b and incorrectly gave a reason for an increase in sulphur dioxide levels (e.g. the opening of the third smelter). Some inappropriately linked the reduction in sulphur dioxide emissions to the use of catalytic converters in cars.
\nOverall this question was poorly answered by many candidates with most describing the vegetation damage illustrated in Figure 6(c), rather than explaining the reasons for the variation in damage observed. Many responses did not link the vegetation damage to the release of pollutants from the smelting factories in Norilsk or how these pollutants may be dispersed in the environment.
\nFigure 3(a): Graph showing Icelandic population change over time
\nFigure 3(b): Age-gender pyramid for Iceland in 2014
\n[Source: adapted from CIA World Factbook]
\nWith reference to Figures 3(a) and 3(b) describe the trends in Iceland’s population dynamic
\nno population prior to 874;
steady increase in population between 874 and 1700;
slight decline/no increase in population between 1700 and 1800;
exponential increase in population since around 1800-1900/significant increase in population from around 1900 onwards;
over recent years/past 24 years, birth rates are stabilizing/slight decline in birth rates/less children/reduction in population growth rate/population pyramid suggests population is stabilizing/entering/moving towards stage 4 of the demographic transition model (DTM);
Responses varied widely, some candidates only commented on one rather than both figures. Description of 3a sometimes was too generalised without reference to dates and associated changing trends.
\nFigure 6(d): The Nadezhda smelting plant in Norilsk opened in 1979
\nThe plant may be a possible source of the water discolouration.
\n[Source: NASA Earth Observatory image by Jesse Allen, using Landsat data from the U.S. Geological Survey.]
\nFigure 6(e): Daldykan River in Norilsk
\n[Source: © Liza Udilova / Greenpeace.]
\nDescribe a practical strategy using a biotic index to provide evidence that the Daldykan River (Figures 6(d) and 6(e)) is damaged by effluent from the metal processing plant.
\nWhen measuring levels of pollution, state one advantage of using a biotic index compared to measuring the pollutants directly.
\nAdvantage:
\n\n
When measuring levels of pollution, state one disadvantage of using a biotic index compared to measuring the pollutants directly.
\nDisadvantage:
\n\n
identify sampling sites upstream and downstream of plant/town / sample before and after effluent is released; sample invertebrate populations / e.g. using kick samples/nets;
identify and count numbers of each species; determine the absence/presence of indicator species;
calculate from this data the biotic index for each site / e.g. use BMWP/Simpson’s Diversity Index/Trent Biotic Index; repeat sampling throughout the year;
Do not accept ‘use of fish’.
Do not accept only ‘measure biodiversity’.
measures actual impact on living organisms/ecosystem;
can see if pollution has occurred in the past/in the lifespan of the indicator species even if the water is clean now;
records seasonal changes in the impact of pollutants;
does not require complex chemical analysis;
does not require expensive equipment / is relatively cheap;
Do not accept ‘using a biotic index is quicker than measuring pollutants directly’.
Do not accept ‘provides a numerical value for the level of pollution’.
Do not accept ‘can be used as a reference for future monitoring’.
does not identify pollutant causing impacts / does not measure the level of the actual pollutant;
does not directly measure the level of pollution;
does not help identify source responsible for impacts;
inaccurate as populations change naturally (during the season) / impacts could be due to natural changes in environment/other factors;
requires knowledge of/ability in identification of organisms for area;
requires existence of identification keys;
Do not accept only ‘it is not exact/precise’.
Do not accept ‘method kills organisms’.
Overall this question was poorly answered. A significant number of candidates did not attempt to answer the question, leaving a blank response. Few candidates were able to fully describe how the river could be sampled when using a biotic index. Some students inappropriately suggested the use of BOD, pH, turbidity, colour, fish, Lincoln's Index or vegetation around the river.
\nThere was a wide range of responses for this question, with many correctly linking their response to the actual impact on living organisms. However, it was clear that a significant number of candidates did not understand what a biotic index was and incorrectly discussed the use of abiotic parameters such as pH.
\nMany candidates correctly answered this question. A popular response was \"it does not measure the level of the actual pollutant\". A significant number of responses were too vague, such as \"it is not exact or precise\".
\nFigure 3 represents a system of aquaculture with four groups of harvestable species.
\nFigure 3: Integrated aquaculture
\n[Source: Adapted from and reprinted with permission from Ocean Conservancy]
\n\n
Identify one producer in the system illustrated in Figure 3.
\nOutline one reason why aquaculture production has increased globally.
\nDescribe two negative environmental impacts that may arise from integrated aquaculture.
\nExplain why this system may cause fewer environmental impacts than systems that farm only fish.
\nalgae/seaweed/sea grass
\nincreased food demand from increasing population/affluence;
health benefits / change of diet preferences;
depletion of marine fisheries / considered more sustainable;
limited arable land for food production;
more economically efficient/profitable;
requires less resources/expertise (boats, fishermen, etc) than wild fisheries;
technology/technological methods have improved.
Award [1 max].
\nescaped fish impact wild stocks through genetic degradation/disease/competition;
high density populations lead to more disease;
farmed species may consume/displace food species for local populations;
loss/degradation of habitat due to clearance for aquaculture / nets/cages may trap/endanger local species;
introduction of non-native species;
pollution due to use of medication/growth hormones/pesticides.
NB do not credit high nutrients/eutrophication/low diversity/high BOD or any other impacts that integrated agriculture actually limits or reduces (as indicated in responses to question 3(d)).
Award [1] for each correct answer identified, up to [2 max].
polyculture helps maintain biodiversity/complexity/resilience in the environment;
(polyculture) allows for species to recycle wastes of other species;
lobsters/mussels will reduce particles of organic waste/faecal matter/excess feed;
(reduction of particles will) reduce BOD/decomposition and oxygen consumption;
filtration by the mussels will improve water clarity/photosynthesis;
cropping/harvesting algae will prevent build-up of nutrients/eutrophication;
algae will absorb excess CO2 reducing acidification of water;
algae will release oxygen limiting anaerobic conditions;
food is provided naturally from within system/feeds made up from wild populations are not required.
Award [1] for each correct answer identified, up to [4 max].
\nThe vast majority of candidates identified a “producer” in the system.
\nThe great majority identified a valid reason for rise in aquaculture
\nA good proportion of candidates identified at least one potentially negative impact of aquaculture.
\nSurprisingly few candidates could suggest more than one (occasionally two) advantages of integrated culture. It was as if they had not registered the 4 marks available and were satisfied once they had given just one possible reason.
\nFigure 7(a): Fact file on taiga
\nFigure 7(b): Total exports of timber (in units of thousand cubic metres) from Russia between 2012 and 2014
\n[Source: With permission from GRID-Arendal. Source adapted.]
\nOutline one ecological service provided by the Siberian taiga.
\nWith reference to Figure 7(b), calculate the percentage of timber exports to China between the years 2012–2014.
\nExplain how deforestation in the taiga may impact the world’s oceans.
\nState one natural limiting factor to the successful restoration of taiga through replanting.
\nprovides habitat for animals/birds;
(photosynthesis) acts as a carbon sink/absorbs CO2 reducing greenhouse emissions;
(photosynthesis) releases O2 necessary for living organisms;
filters water / maintains water table;
cools/moistens climate through evapotranspiration / source of moisture for precipitation;
vegetation prevents soil erosion;
increases/maintains biodiversity (increasing/maintaining resilience of biosphere);
pollination of plants/crops;
Do not accept only ‘photosynthesis.
Do not accept provision of goods e.g. timber/food.
Do not accept cultural, intrinsic or aesthetical benefits e.g. spiritual/tourism/recreation.
For credit response must focus on ecological service/function.
\n
Note: Units are not required for credit.
\nremoving vegetation increases CO2 levels in atmosphere which promotes global warming / deforestation increases melting of permafrost which releases CO2 and CH4 which promotes global warming;
increased CO2 levels lead to ocean acidification (reduction in ocean pH) / carbon stores within oceans increase;
ocean acidification causes the bleaching of corals/corrosion of shells/loss of marine species/diversity;
global warming/higher temperatures cause thermal expansion which raises sea levels;
global warming/higher temperatures cause the melting of glaciers which raises sea levels;
higher sea water temperature causes bleaching of corals/loss of breeding grounds for marine organisms/loss of marine species;
deforestation leads to an increase in surface runoff which raises sea levels;
increase in freshwater input results in a reduction in seawater salinity;
reduction in forest cover so more soil erosion (by rain), leading to sediment input to the ocean / roots no longer hold soil in place which results in soil erosion, leading to sediment input into the ocean;
warmer waters can lead to a reduction in oxygen levels within the oceans;
lower oxygen levels within the oceans can reduce biodiversity;
Do not accept ‘the transport/exportation of timber causes ocean pollution’.
Do not accept only ‘global warming causes sea-level rise’.
Do not accept that deforestation causes an increase in nutrient run-off that causes eutrophication (taiga soils are nutrient poor).
Do not accept ‘climate change’ instead of the term ‘global warming’.
Accept other reasonable responses.
nutrient poor soils / low temperature / low rainfall / limited growing season / limited amount of sunlight / slow growth rates / permafrost inhibits plant growth;
\nDo not accept ‘wildfires / grazers/animals eat the plants/seedlings’.
Do not accept just ‘temperature/rainfall/soil fertility/time it takes for trees to grow/long mature time for trees’.
Many candidates correctly answered this question with popular responses including the taiga acts as a carbon sink, absorbs carbon dioxide or produces oxygen (via photosynthesis). However, a significant number of responses did not focus on an ecological service or function but instead included provision of goods e.g. timber.
\nThe majority of candidates successfully performed this calculation. Incorrect rounding, i.e. 60 %, was the most common source of error.
\nResponses varied widely for this question. Good responses gave detailed answers that linked deforestation to impacts in the ocean, ranging from ocean acidification to sea-level rise. A common error was to assume that eutrophication would occur as a consequence of deforestation despite the taiga soils being nutrient poor.
\nThis question was generally answered well by most students. Common errors included stating \"time it takes for trees to grow\" or stating only \"temperature\" or \"rainfall\" rather than \"low temperature\" or \"low rainfall\".
\nOutline how four different factors influence the resilience of an ecosystem.
\nExplain how a community of trees in a woodland may be considered a system.
\nDisturbance of the composition and processes of the atmospheric system through human activity always disturbs the equilibria of marine systems.
\nDiscuss the validity of this statement with reference to named examples.
\nValid factors:
greater diversity of components/species increases resilience;
complexity of interactions/developed food webs increase resilience;
establishment of keystone species increases resilience;
larger storages/stores / more abundant/productive resources (nutrients, water, sunlight, reproductive rates, biomass etc) increase resilience (NB for credit, there must be indication of abundance in these resources, and if multiple examples are given like those in brackets, there is still only [1 max] allowed for this MP);
larger size of the system increases resilience;
strong negative feedback systems increase resilience;
strong positive feedback mechanisms may decrease resilience;
human impact degrading structure/diversity/abundance will decrease resilience;
a steady state equilibrium/balanced inputs and outputs (as in climax communities) increases resilience;
systems being close to a tipping point decrease resilience.
Accept converse statements.
Award [1] for each correct factor identified, up to [4 max].
If valid factors are identified, but their effect on resilience is not, award [1] for each TWO factors up to [2 max] (ie FOUR factors). Eg identifying TWO factors and their effect on resilience, along with TWO factors but no specified effect would score [2+1=3] total OR eg TWO factors and their effect, along with ONE with no effect would score [2+0=2] total OR eg FOUR factors with no effect ([1+1=2] total).
A community of trees in a woodland has the following features of a system:
individuals/species of trees are the components of the system;
these components are interrelated/interdependent/form an integrated whole;
eg may regulate populations through competition / contribute to succession of community;
it has flows/transfers of matter/energy between components/storages;
eg leaf fall may provide nutrients through decomposition to other trees / pollination/genes/food storage in seeds / glucose is transported from leaves around tree;
components carry out processes/transformations;
eg photosynthesis/respiration/growth;
it is an open system exchanging matter and energy with surroundings;
eg absorption of solar energy / provision of nutrients for non-tree species (NB mark for either example of matter or energy, not both);
it has feedback mechanisms to maintain equilibrium/balanced inputs and outputs;
eg more seed production → more competition between seedlings → fewer viable offspring / death of trees → more light entering canopy → more tree growth.
Award [1] for each correct suggestion, up to [7 max].
Award [4 max] for identifying relevant generic features of system (given above) and [4 max] for examples of these within a tree community (beware of responses that are looking at entire woodland ecosystem as a system rather than the tree community alone). Credit alternative examples of equivalent validity/relevance and detail.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQuestion 4 was one of the least popular but often produced quite good responses. In part (a), a number of candidates could go no further than biodiversity (in its various forms) as a contributing factor to resilience. Some too were under the false impression that external impacts affect resilience, whereas resilience is not dependent on the absence of threats, but is the inherent ability of the system to resist such threats. Of course, human impacts such as hunting/harvesting etc may affect resilience by depleting those qualities that contribute to resilience (diversity/productivity etc) but this needs to be specified to become a relevant influence on resilience, as such.
\nMost candidates were able to recognise a tree community as an open system and give examples of exchange of matter/energy and transformations within that system. Some responses became confused by extending the boundary of the system addressed to the entire woodland ecosystem such that some examples given were irrelevant.
\nMost candidates were able to find at least one or two valid links between atmospheric disturbances and marine systems particularly between global warming, rising sea levels, changing currents/coral bleaching etc. A significant minority mistook “marine” to mean simply “aquatic”, and therefore addressed irrelevant material relating to freshwater systems. There was a quite common confusion that acid rain was a cause of ocean acidification whereas acid rain has negligible impact on marine systems. The inclusion of “always” in the question stem made it possible for candidates to develop counter-examples (like photochemical smog/acid rain) but few took advantage of this opportunity, limiting the depth/balance of their analysis.
\nFigure 8(c): Example of a Siberian food web
\n[Source: [Reindeer] Natalia Kollegova/Pixabay [Siberian tiger] Pixabay [Wild boar] Pixabay [Arctic hare] Pixabay [Wolf] Pixabay [Siberian larch] Pixabay [Siberian wheatgrass] USDA PLANTS Database [Bearberry] Arctostaphylos uva-ursi, Sten Porse https://en.wikipedia.org/wiki/Bearberry#/media/File:Arctostaphylos-uva-ursi.JPG CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/.]
\nOutline the impact that a reduction in the tiger population may have on other populations in the food web shown in Figure 8(c).
\nOutline why a reduction in the Siberian tiger’s population may increase its probability of extinction.
\nit is likely to lead to an increase in its prey populations/ reindeer/hare/wolves/lemming/boar;
…which in turn may lead to decreases in their prey/food populations/hares/reindeer/lemming/plants/larch/wheatgrass/bearberry;
…causing fluctuations in population size/instability/reduced resilience throughout web;
Do not accept ‘collapse in food chain’.
\nsmaller population will reduce its gene pool/genetic diversity;
…reducing its resilience / making it more vulnerable/less adaptable to changes in environment/disease/resource availability;
harder to find a mate / reduce successful pairing/mating/reproduction/favourable gender ratios;
increase rarity in tiger population may result in an increase in demand/market/trade value (increasing probablity of extinction);
Do not accept 'tigers do not reproduce fast'.
\nThis question was very well answered by most candidates.
\nAlthough most students were able to give one reason, such as \"not being able to find a mate\", few gave a second reason required to achieve the full two marks.
\nFigure 8(a): Fact file on Siberian tiger (Panthera tigris altaica)
\nFigure 8(d): Siberian tiger population in Russia
\nFigure 8(e): Causes of tiger mortality in and near Sikhote-Alin Biosphere Reserve, 1992–2005
\n[Source: Russia Program, Wildlife Conservation Society.]
\nConservation measures for the Siberian tiger between 1940–2010 involved tagging, setting up reserves, and bans on hunting and trade.
\nWith reference to Figures 8(a), 8(d) and 8(e), evaluate the relative success of these measures.
\nthe ban on hunting was followed by a small/triple increase in tiger population;
…but Figure 8(e) shows poaching continued well beyond this / was still recorded until 2005;
the ban on trade/CITES convention was followed by very significant increase in tiger population;
use of tagging and reserves showed little further increase in tiger population;
but population was already increased before reserves were introduced / reserves may have helped maintain higher populations;
the rate of increase has slowed, suggesting tigers have reached a carrying capacity;
Note: Must include strength, weakness and conclusion for [3] marks. Award [2 max] if no conclusion provided.
\nAlthough most candidates achieved some marks for this question, few achieved all 3 marks. Many did not recognise the requirements of the command term 'evaluate' and that a strength, a weakness, and overall appraisal was necessary to achieve full marks. Few candidates evaluated the different measures by comparing their relative success.
\nFigure 8(e): Causes of tiger mortality in and near Sikhote-Alin Biosphere Reserve, 1992–2005
\n[Source: Russia Program, Wildlife Conservation Society.]
\nFigure 8(f): Increase of logging roads between 1984 (228 km) and 2014 (6278 km) in Primorsky Krai
\nIn 2015, the logging company, the local authority, and an international NGO agreed to dismantle unused logging roads in the area.
\n[Source: Russia Program, Wildlife Conservation Society.]
\nWith reference to Figures 8(e) and 8(f), outline how the decision to remove logging roads in 2015 may benefit the tiger populations.
\nhabitat will become less fragmented by the roads;
reduced fragmentation may allow access to important resources, e.g. food/water / removal allows for regeneration of tiger habitat through succession;
populations will be less isolated improving gene pool/diversity/resilience;
reduces noise/disturbance/stress/pollution associated with roads/traffic;
reduces mortality through road kill;
makes habitats less accessible to human disturbance/poaching / it could reduce contact between tigers and humans which could result in fewer tigers being killed//poached;
Do not accept ‘habitat size is increased / results in a larger habitat / there is more vegetation for prey’.
Do not accept only ‘population is less accessible’.
Do not accept only ‘poaching is more difficult/harder’ without reason.
Do not accept ‘tigers are better able to hide’.
The majority of candidates achieved at least one mark for this question. Many only gave one rather than the two reasons required. The most popular response was a reduction in roadkill. Few candidates referred to a reduction in habitat fragmentation through removal of the roads.
\nTo what extent might it be better to consider environmental issues at a global, rather than a local level, when planning for sustainable development in Siberia?
\nArguments that support addressing issue at global level [4 max]:
\nArguments that support addressing issue at local level [4 max]:
\nConclusion/opinion [1 max]: e.g. “due to the interconnected nature of environmental systems, action needs to be taken at a global level e.g. through international agreements, however these then need to be implemented at a local level to be successful”;
\nNote: An isolated statement/opinion, e.g. “Environmental issues are best addressed at a global level” should not be considered as a valid conclusion/opinion without supporting evidence.
Award [5 max] if there is no conclusion/opinion.
Accept other reasonable responses supported by information in the resource booklet.
Responses varied widely for this question with most candidates achieving some marks. Some responses were well focused, considered both sides of the argument and used evidence given within the resource booklet to support their key points. Whereas other responses were too generic and did not use the information provided or gave only one side of the argument. Few responses gave a balanced conclusion supported by evidence.
\nThe hole in the ozone layer over Antarctica, discovered in the 1980s, was caused by chlorofluorocarbons (CFCs). The Montreal Protocol requires the use of hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (HFCs) instead of CFCs (Figure 3). However, these two gases are also linked to environmental problems (Figure 4).
\nFigure 3: Comparison of the effects of CFCs, HCFCs and HFCs
\n[Source: Avipsa Mahapatra, Climate Lead, Environmental Investigation Agency, Washington D.C.]
\n\n
Figure 4: HCFCs and HFCs cause less damage than CFCs but still
affect the environment
[Source: © 2016 Cognitive www.wearecognitive.com / Children’s Investment Fund Foundation (CIFF) www.ciff.org]
\nIdentify two possible consequences for life on Earth resulting from the depletion of stratospheric ozone.
\nOutline why the Montreal Protocol may be considered the world’s most successful environmental treaty.
\nOutline why governments agreed to phase out the use of HFCs from 2019 in the Kigali Amendment to the Montreal Protocol.
\nIdentify one advantage of staggered dates for the phasing out of HFCs for countries at different levels of economic development.
\nIdentify one disadvantage of staggered dates for the phasing out of HFCs for countries at different levels of economic development.
\nincreased skin cancer/melanomas/skin aging/mutations;
increased eye abnormalities/cataract/photo allergy/blindness;
weakening of immune systems;
disrupts plant growth / damage leaves thus reducing photosynthesis / loss of plant species;
damage to phytoplankton in oceans / reducing base of food web;
causes death of krill/zooplankton/amphibian larvae reducing diversity/food for higher trophic levels.
Note: Do not give credit for responses simply stating it leads to increased UV (Q asks for impact on “life”). Do not credit responses identifying consequences linked to GW. (Increased UV has negligible DIRECT impact on GW however, INDIRECTLY, eg by reducing primary productivity, it may contribute to GW, but such an indirect link would need to be explicitly stated to gain credit).
\nclear evidence of successful reduction in CFC use/ozone depletion/size of ozone hole;
protocol prompted production of alternatives to replace CFCs allowing smooth phase-out;
financial assistance was offered to assist in phase out of CFCs (Multilateral Fund);
demonstrated it was possible for governments to work multilaterally;
led to changes in the behaviour of individuals and societies;
very large number of signatories;
secured binding environmental agreements/legal commitments with which countries/industries complied;
there was a widespread/common acceptance/understanding of the effect of CFCs (amongst scientists/public/politicians).
Note: Simply stating “CFCs were banned” or “banning of CFCs” is not sufficient for credit.
\nbecause HFCs are bad for climate/contribute to global warming;
realisation that environmental issues need to be addressed at an intergovernmental level;
realisation that changes in behaviour are necessary to protect the environment in the future;
in response to development in scientific understanding of issue;
rich countries agreed to provide financial assistance for poorer countries to phase out HFCs;
because technological development has found alternatives to HFCs.
allows less developed countries more time to raise necessary funding;
allows less developed countries time to develop/import necessary technology/infrastructure;
allows less developed countries time to introduce significant changes in policy/governance;
deadlines are more reasonable so more countries are likely to commit to change;
issue can start being addressed sooner by more developed countries.
may prolong achievement of complete/global phasing out;
may reduce action to a lower priority than necessary in some countries;
may prompt some multinational companies to relocate to countries with later deadlines;
developed countries, given shorter deadlines, may be more dependent on HFCs so have more to do;
countries avoiding early phase out may benefit from production/trade of HFCs;
cost of early change/application of untested substitutes may lead to conflict from more developed countries;
conflicts arising from different treatments between countries may undermine overall agreement.
Although many were able to identify impact of ozone depletion on human skin, probably a good half of the candidates were still perpetuating the erroneous myth that ozone depletion contributes significantly to global warming.
\nWell answered by the great majority, though many failed to seek out a second point to gain the full two marks.
\nAlthough the Kigali agreement is not specified in the syllabus, candidates only needed to apply what they knew to the new information presented in this question. Testing such ability to apply their knowledge in new contexts is an important aspect of this component of the exam and, for the most part, candidates did well.
\nThese questions proved challenging for many candidates involving a degree of analytical thought and processing.
\nThese questions proved challenging for many candidates involving a degree of analytical thought and processing.
\nDistinguish between the terms niche and habitat with reference to a named species.
\nSuggest the procedures needed to collect data for the construction of a pyramid of numbers for the following food chain:
\nQuantitative models are frequently constructed to show the flow of energy and cycling of matter in natural systems.
\nTo what extent can these models be useful in assessing the sustainability of named food production systems?
\nhabitat is the kind of (biotic and abiotic) environment in which a species normally lives;
eg lions are found in tropical grasslands;
whereas its niche refers to all its interactions with its (biotic and abiotic) environment;
eg the prey that it eats / its vulnerability to parasites / access to fresh water;
habitat may be shared by many species / niche is more limited to a single species;
eg different cat species inhabit tropical grasslands but only lions hunt in groups and so tend to take larger prey.
Award [2 max] if no examples are given. “Role of species within ecosystem” would be acceptable as definition of species, but not “job” which is anthropomorphic and only addresses impact of species on system, not the mutual relationship.
Accept any relevant/valid/equivalently detailed examples to those given.
Award [1] for each correct answer, up to [4 max].
quadrats can be used for counting/sampling snail/plant populations;
need to be randomly distributed within area of system;
total estimated by multiplying mean of samples by total area/sample area;
mark–release–recapture/Lincoln index can be used for bird/snail species;
individuals are caught using traps/nets/bait;
individuals marked by some means that is indelible/harmless/easily visible to investigators;
individuals released/allowed to redistribute before resetting traps;
ratio of marked : unmarked in recapture is recorded and used to estimate total population;
bird populations may be estimated by aerial photographs/birdsong recordings that allow capture/recapture analysis;
bars/histograms proportional to each total population are drawn.
Award [1] for each correct suggestion, up to [7 max].
Accept alternative procedures of equivalent validity.
The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQuestion 5 was the least popular choice. In part (a) the majority could distinguish “habitat” and “niche”. Although “role in an ecosystem” is an acceptable synonym for niche, “job” is less so …being somewhat anthropomorphic and only focusing on the impact of the species rather than its mutual relationship with the environment. A good number of candidates spent unnecessary time distinguishing fundamental and realised niches while failing to address specific requirements of question.
\nMajority of candidates had a sound understanding of quadrat sampling and mark–release–recapture methodologies, though generally lacked sufficient detail to gain more than 5 of the available 7 marks.
\nMajority of responses were very superficial. Firstly, few candidates were able to link energy flow and mineral cycles with food production, and secondly, few demonstrated any sound grasp of sustainability in this context. The relationship of sustainability and sustainable yields with e.g. steady state equilibria, balanced inputs and outputs, cycling, transfer efficiency were rarely addressed. It was as if candidates had only explored ecosystem models, food production and sustainability in isolation from one another and were unable to make appropriate links.
\nWith reference to named examples, distinguish between a primary and secondary pollutant.
\nExplain how organic waste may be an effective fertilizer in terrestrial systems but a source of pollution in aquatic systems.
\nTo what extent can different environmental value systems contribute to both causing and resolving the problem of water scarcity?
\na primary pollutant is one which is active on emission / directly impacts the environment;
eg CO2 is released from burning fossil fuels and actively contributes to global warming / CFCs are released from aerosols and actively contribute to ozone depletion;
a secondary pollutant is one formed from a primary pollutant through physical/chemical change;
eg CO2 combines with sea water to form carbonic acid that leads to impacts on calciferous shelled organisms or corals / NOx combines with water to form acid precipitation / NO2 forms PAN/ozone (that contributes to photochemical smog).
Award [2 max] if no examples are given.
Examples of primary pollutants need to include their direct impact (eg NOx can be either primary or secondary without such specification) and examples of secondary need to include the process leading to their pollutionary impact).
Award [1 max] for example of primary, and [1 max] for example of secondary.
In terrestrial systems [4 max]:
organic waste such as cattle manure/compost can be added to soil as fertilizer;
its decomposition releases nitrates/phosphates/nutrients that promote plant growth;
the slow release will help to prevent run-off/eutrophication/red tide/algal bloom of water bodies;
improves soil quality/structure / making it less prone to erosion/compaction / increases plowability;
it is similar to the natural organic waste in a terrestrial system so may not be a pollutant.
In aquatic systems [4 max]:
organic waste eg sawdust/domestic sewage/agricultural run-off can be discharged into aquatic systems;
increases turbidity/floats on surface/algal growth reduces light penetration and primary productivity of system;
its decomposition leads to bacterial absorption of O2 / adds high BOD reducing O2 availability;
this is a limiting factor in aquatic (not terrestrial) systems (negatively) impacting aquatic life;
(decomposition also) releases nitrates/phosphates/nutrients leading to eutrophication/red tide/algal blooms;
domestic sewage/sawmill effluent may contain non-biodegradable organic pollutants/toxins/pathogens;
can pollute drinking water sources for human populations/animal species.
Award [1] for each correct explanation, up to [7 max].
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials
\nQuestion 6 was a popular choice. In part (a) distinctions between primary and secondary pollutants were often valid, though a good number of candidates confused the distinction with point v non-point pollution.
\nCandidates generally performed well on this question, usually gaining the bulk of their credit from detailed and valid descriptions of eutrophication.
\nMajority of candidates were able to distinguish environmental value systems and relate their ideologies to issues of water scarcity hence scoring within the 4–6 range. Commonly, there was vague grasp of anthropocentric values and some confusion of these with more cornucopian values. Responses tended to fall short of the higher markband due to a lack of explicit examples, evaluative argument/counterargument or an effective conclusion.
\nOutline two ecosystem services in a named biome.
\nExplain the causes, and the possible consequences, of the loss of a named critically endangered species.
\nUsing examples, discuss whether habitat conservation is more successful than a species-based approach to protecting threatened species.
\nExamples may include:
\nTundra:
permafrost/glaciers in tundra;
…provides important storage in hydrological cycle;
ice in tundra provides reflective surface/increases planetary albedo;
…thus moderating global temperatures;
Wetlands:
decomposers/high productivity in swamps/wetlands;
…provides filtration of inorganic nutrients / water purification;
storage of water in wetlands;
…prevents flooding / provides ideal resting grounds for migratory birds;
Tropical rainforests:
high biodiversity in TRF;
…promotes ecotourism/recreation;
high rate of photosynthesis in TRF;
…maintains balance of O2/CO2 in atmosphere;
Boreal/temperate forests:
tree populations in boreal/temperate forests;
…prevent soil erosion on mountainsides;
forest canopies in forests;
…provide shade/shelter/habitat for diversity of species.
Note: Numerous valid examples can be credited, but to gain full credit (2 marks per service) candidates must identify relevant component of biome [1 mark] and outline the service it provides [1 mark] as in MPs above.
Be careful only to credit “services” (maintenance/establishment of favourable conditions) and not “goods” (consumable/harvestable/physical products).
Award [2 max] if no biome is identified. If more than one biome is given, credit only highest scoring biome addressed.
\nCauses [4 max] could include:
habitat loss / deforestation;
habitat degradation / pollution;
narrowly distributed / endemic;
poaching / overhunting;
illegal trafficking of species;
disease;
small population size/gene pool / inbreeding;
specialised niche;
slow reproduction rate / specialised reproductive behaviour;
high trophic level/top predator;
low/negative cultural value;
influence/competition/predation from invasive species.
Consequences [4 max] could include:
loss of an aesthetically attractive organism;
loss of ethically significant life / breach of biorights;
loss of biodiversity;
increase in organisms upon which the species fed or competed with;
decline in other organisms due to loss of food source;
if keystone species, widespread impacts/cascade effects on food chains/ecosystem;
economic costs from loss of ecosystem services provided by the species;
economic costs from loss of tourism opportunities;
social impacts on local culture as important/significant cultural loss.
Accept reference to decline of any species that is endangered, critically endangered or currently extinct.
If more than one species is addressed only credit the highest scoring example.
Note: MPs given above need to be embedded in a valid case-study/account of a named species to gain full credit and not simply listed as bullet points as per MPs. e.g. The distribution of thylacine/Tasmanian tiger became limited/endemic to Tasmania in early 20th century (MP3); As it was thought to be a threat to sheep farming, it was hunted (MP11); bounties were given to promote the level of hunting (MP4). The introduction of domestic dogs spread disease amongst thylacines (MP6) leading to further decline.
\nIf MPs are simply given without such context of a named species and its specific issues then give [2 max] for causes and [2 max] for consequences.
\nAnswers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nThis question frequently revealed some inaccurate grasp of concepts where candidates confused the term biome with specific ecosystems (e.g. Amazon rainforest) and/or ‘services’ with ‘goods’.
\nGenerally well-answered, but where candidates failed to gain significant credit, it was largely through not having a specific named case study to which they could refer. A good number of candidates paid little heed to the number of marks available and were satisfied to name just one cause and one consequence.
\nGenerally, responses to this question evaluating habitat-based and species-based conservation were of good quality although, again, candidates without specific case studies to which they could refer did less well.
\nFigure 3(a): Hurricane history of Dominica since 1900
\n[Source: Adapted from Dominica’s history with tropical storms. Available at: http://www.hurricanecity.com/city/dominica.htm.]
\nFigure 3(b): Average global sea surface temperature, 1900–2015
\n[Source: NOAA.]
\nFigure 3(c): Impacts of Hurricane Maria
\n[text] Adapted from ACAPS, 2018. Dominica: The impact of Hurricane Maria. Available at:
https://www.acaps.org/sites/acaps/files/products/files/20180131_acaps_disaster_profile_dominica_v2.pdf.
[left image] Photo credit: Marica Honychurch.
\n[right image] Photo courtesy of CARICOM, September 21, 2017,
https://caricom.org/carpha-ready-to-assist-dominica/.
Figure 3(d): Landslide caused by heavy rains after a hurricane
\n[Source: Photo courtesy of Jodie Dangleben.]
\nUsing Figure 3(a), identify why Hurricane Maria was so destructive.
\nDescribe the relationship between sea surface temperature in Figure 3(b) and hurricane wind speed in Figure 3(a).
\nWith reference to Figures 3(c) and 3(d), outline how Hurricane Maria has reduced Dominica’s food availability.
\nWith reference to Figure 3(c), explain three ways in which Hurricane Maria has affected ecosystem services provided by Dominica’s forests.
\nstrongest hurricane in Dominica’s history / fastest (maximum) wind speeds/wind speed of over 250 km/hr and therefore most destructive;
has been many/22 years since the last hurricane, so people were not prepared;
last hurricane had much lower maximum wind speeds, so people were not expecting such a damaging storm;
Note: Do not accept only ‘very high wind speed’.
\nrising sea temperatures result in greater hurricane strength/stronger maximum wind speeds;
the two largest hurricanes occurred after 1979, when sea temperatures increased above the 1971–2000 average;
there is no relationship/no clear relationship;
the relationship is not consistent as smaller storms occur even after sea surface temperatures exceed the 1971–2000 average/higher sea temperature in the early1940s did not result in a hurricane;
100% of food crops were destroyed in the hurricane (reducing food availability);
damage to coral reef ecosystems reduced fish catch;
wild food sources within the forest (eg nuts, fruits) destroyed;
delays to food supply due to time needed to regrow local crops;
food transportation disrupted due to loss of/damage to roads/bridges/airports/ports;
soil erosion/landslides reduced soil fertility/area available for cultivation;
heavy rains leached soil nutrients/reduced soil fertility;
contamination of freshwater with oil/chemicals reduces water available for irrigation;
disruption to electricity supply resulted in spoilage / unable to store food due to lack of refrigeration;
Note: Do not accept only ‘hurricane damages food crops’.
\nreduction in photosynthesis so less oxygen produced;
reduction in trees results in loss of carbon sink / reduction in trees/photosynthesis reduces carbon dioxide uptake;
loss of leaves means more precipitation reaches the ground causing surface runoff/causing more soil erosion/loss of soil nutrients;
less uptake of water by plants resulting in increased flooding;
loss of plants/trees reduces water infiltration into aquifers/groundwater;
loss of habitat for species (reducing biodiversity);
loss of habitat reduces food supply / loss of trees reduces food sources;
loss of trees reduces available timber/wood for human use;
loss of trees means reduced transpiration, reducing atmospheric moisture, reducing precipitation and thereby affecting local climate/microclimate;
loss of shade means hotter ground temperatures/loss of cooling effect of forest on local climate/microclimate;
Note: Accept other reasonable responses which are specific to ecosystem services provided by forests. Hence, do not accept ‘contamination of freshwater by oil/chemicals reduces water/fish supplies / erosion of soils reduces nitrogen cycling/nutrient availability’.
\nMost candidates answered this question well. A few responses such as 'increased or high wind speed' were too vague for credit.
\nMost students achieved one mark for this question with most identifying a positive correlation between sea surface temperature and hurricane wind speed. Few candidates gave examples that supported this relationship or recognised that it was not a strong relationship with a number of anomalous periods.
\nThis question was answered well by most candidates. Some responses lacked the necessary detail required for full marks.
\nResponses varied widely for this question. Many candidates did not focus on ecosystem services provided by the forest as required and included non-relevant material e.g. contamination of freshwater with oil and chemicals or damage to the coral reefs.
\nOutline the factors that lead to different environmental value systems in contrasting cultures.
\nExplain why the harvesting of a named aquatic species may be controversial.
\nDiscuss strategies that can be used to improve the sustainability of food production systems.
\nFactors may include:
\ncultural ie some cultures place a high value on nature and thus have a more ecocentric EVS;
religious ie some religions deify certain organisms/landscapes and thus have a more ecocentric EVS;
economic ie some would argue that more economically wealthy societies tend towards a more technocentric/anthropocentric EVS;
socio-political ie some would argue that a society with a strong social political movement would tend towards a more anthropocentric EVS;
experience/history ie societies that have experienced anthropogenic disasters may become more prone to adopt ecocentric value systems.
Award [3 max] if only one category of EVS is addressed (question asks for “contrasting cultures”).
\nNote: Full credit can be given where candidate gives a specific example to outline link between factor and EVS. However, if factors are simply named/listed without any explanatory outline broadly linking them to EVS, then award just 1 mark for every TWO valid factors identified up to 2 max.
\nArguments against may include:
ethical issues arise over biorights of the aquatic species;
harvesting may contravene international conservation agreements;
species may be endangered/threatened with extinction;
some may consider the harvesting method as cruel/unethical;
if unsustainable, whole regions of the ocean may deplete of fish;
ecocentrics may promote veganism and oppose harvest of animal species;
ecocentrics would oppose any large scale harvesting/food production systems.
Arguments in favour may include:
harvesting necessary for some societies for subsistence/survival;
whole economies may be based on harvesting aquatic species;
fishing as a recreation/hobby brings people closer to nature;
aquaculture may allow harvesting without endangering the species;
if harvesting is within sustainable limits it poses no threat to others;
anthropocentrics would support sustainable harvesting;
technocentrics would support achieving maximum yield/greatest economic return;
and whatever technology/harvesting method will be most efficient in achieving this.
eg whales
hunting methods are cruel;
unethical to kill animals;
modern technologies are very efficient allowing no chance to the whale to escape (so it's \"unfair\");
populations are declining / many whale species are now endangered;
conflicts arise over territorial rights among fleet of different nations;
other species (eg dolphins) may be killed in the process / by-catch kill;
large parts are thrown back to sea (so wasting the kill);
increase in illegal whale hunting of endangered species (along with hunting of non-endangered species);
usually harvesting is not sustainable (as it is economic profit that counts);
in most countries (Norway, Japan, Iceland) whaling is not necessary for their subsistence nowadays;
conflicts arise with ecocentric NGOs opposing whaling (eg Greenpeace).
Award [6 max] if no named aquatic species.
Award [4 max] if response only addresses “arguments in favour” (“controversial” strongly implies arguments against).
If more than one species is addressed, credit only the highest scoring example.
Answers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nMost candidates could list some valid factors that may influence value systems but were often not able to outline link to particular viewpoints.
\nMajority of candidates could identify some controversial aspects of aquatic harvesting but would often make insufficient points to achieve all the marks available.
\nMost candidates were able to identify and describe effective strategies for sustainable food production but often lacked any element of counterargument or evaluation necessary for a ‘discuss’ question.
\nFigure 3(d): Landslide caused by heavy rains after a hurricane
\n[Source: Photo courtesy of Jodie Dangleben.]
\nFigure 3(d) shows a landslide caused by heavy precipitation on a steep slope. Outline one technique that could be used by farmers in Dominica to reduce soil erosion.
\ncontour ploughing;
… slows down surface runoff;
… allows infiltration to occur;
… less sediment is washed into the rivers;
stone lines;
… slows down surface runoff;
… allows infiltration to occur;
… less sediment is washed into the rivers;
mulching;
… residue on the surface of the soil reduces rainfall impact;
... residue on the surface holds water, reducing runoff;
… less sediment is washed into the rivers;
terracing;
… flat steps on steep slopes slow down surface runoff;
… allows infiltration to occur;
… less sediment is washed into the rivers/ flat areas are more stable and the soil is less likely to slide down the slope;
planting trees/agroforestry/intercropping with trees;
...trees intercept precipitation/rainfall, reducing surface run-off / absorb water reducing run-off / increase infiltration due to root systems;
...roots stabilize/hold soil;
...reducing loss of nutrients/top soil;
Note: [1] for naming the technique and [2] for outlining how it reduces soil erosion.
\nMost candidates were able to identify a suitable technique to reduce soil erosion on a steep slope but few were able to outline how the technique worked in sufficient detail for the full 3 marks.
\nOutline how feedback loops are involved in alternate stable states and the tipping points between them.
\nIn 2016, the Earth’s atmospheric levels of carbon dioxide reached 400 ppm. Suggest the potential impacts of high levels of greenhouse gases on human societies in different locations.
\nDiscuss the consequences of changing global per capita meat consumption on the conservation of ecosystems and biodiversity.
\nnegative feedback loops occur when the output of a process inhibits or reverses the same process;
…thus inhibiting change/deviation / maintaining a system in equilibrium/one stable state;
positive feedback loops occur when the output of a process accelerates that same process;
…thus amplifying changes/deviations / driving system away from its equilibrium/stable state;
excessive change/deviation may drive system beyond its tipping point;
…when it will adopt a new equilibrium/alternate stable state.
Credit any of the above MPs if they are clearly shown by means of an annotated diagram or named example.
\nImpacts may include:
increased mean global temperature causing increased use of A/Cs (especially in developed countries);
greater frequency/intensity of extreme weather events causing damage to infrastructure (especially in cities);
long-term changes in climate/weather patterns requiring cultural changes/adaptation in societies;
ocean acidification killing plankton/reducing fisheries (especially significant for coastal populations);
melting permafrost increasing productivity/arable land/water availability (for tundra populations);
decreased water availability/desertification leading to migration/relocation (especially for tropical populations);
biome shifts reducing/enhancing crop productivity (especially significant in crop-growing areas);
biodiversity loss reducing aesthetic value of ecosystems (significant for tourism-dependent societies);
disruption of ecosystem services causing increased flooding (particularly in high rainfall locations);
rise in sea level causing coastal erosion (especially significant to areas dependent on coastal tourism);
coastal inundation causing salinization of underground aquifers/soils (especially for coastal populations);
wider spread of tropical diseases (especially significant for previously sub-tropical areas).
Award [4 max] if there is no reference to different locations (as in brackets above).
Do not credit effects of high levels of greenhouse gases that are not linked to some impact on human societies, at least implicitly as in examples above.
Answers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nThe general grasp of feedback mechanisms and tipping points was strong. This was the highest scoring part (a) question in Section B.
\nThere were a few common faults in addressing this question – firstly, just giving too few examples of impacts of greenhouse gases. Secondly, candidates often failed to link these impacts to human societies as required. And, thirdly, the confusion of ozone depletion and global warming was once more manifest.
\nDisadvantages of meat consumption were often identified at some length but their specific impact on ecosystems & biodiversity were not always made clear. Furthermore, responses often lacked the necessary element of counterargument to achieve any balanced analysis or evaluation.
\nOutline how demographic tools can be used to study a human population.
\nUrban air pollution can become a problem as human populations develop. Evaluate urban air pollution management strategies at the three levels of intervention.
\nExamine the driving factors behind the changing energy choices of different countries using named examples.
\ndemographic tools provide quantitative measures/indicators of changes occurring in the dynamics/growth of populations;
…and can be useful in making comparisons between populations / predictions of future changes;
Crude birth rate (CBR) is the number of live births per 1000 population per year / indicates rate at which births are occurring in a population;
Crude death rate (CDR) is number of deaths per 1000 population per year / indicates rate at which deaths are occurring in a population;
Total fertility rate (TFR) is the average number of children a woman would have in her lifetime in a given population / indicates the rate at which women are producing children;
Natural increase rate (NIR) is the crude birth rate minus the crude death rate / indicates the rate at which a population is growing (ignoring migrational changes);
Doubling time (DT) is the number of years a population will take to double in size at its current rate of growth / indicates how quickly a population is growing compared to its current size;
Demographic Transition Model (DTM) is based on historical population trends showing how populations tend to go through stages of changing birth and death rates as they develop economically / it can be useful for identifying a country’s stage of development/making predictions about its future growth.
Level 1: altering human activity [3 max]:
reducing transport eg promoting public transport/carpooling/regulating private vehicle use;
using alternative/renewable energy sources / promoting availability of electric vehicles;
development/use of more energy efficient appliances/housing / green architecture;
Evaluations:
large investment required to facilitate public transport use/e-vehicle use;
if electricity for transport comes from fossil fuels than simply moving the problem somewhere else;
requires education/campaigns to overcome human intransigence to changing behaviours;
prevents pollution right at source.
Level 2: controlling release of pollutant [3 max]:
use of catalytic converters on transport;
use of scrubbers on industries;
introduce legislation/regulation/for emissions/pollutant levels;
Evaluations:
technological fixes can be very effective/easy to enforce;
wealthy companies may simply budget for fines and continue to pollute.
does not require change in human activities.
Level 3: clean-up and restoration of damaged systems [3 max]:
re-greening areas through tree planting/town parkland;
liming of acidified urban water bodies;
restoration of eroded architecture;
medical treatments for consequent health conditions;
Evaluations:
helps to maintain biodiversity/aesthetic value;
only of short-term value / does not prevent ongoing damage to systems;
can be very expensive processes.
Award [4 max] if no evaluative statements have been given.
Do not credit examples/statements relating to pollution that are clearly not “urban” and/or “air” pollution.
Answers may demonstrate:
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nCandidates could usually identify relevant demographic tools but were often unclear in outlining their use in studying human populations.
\nGenerally well-answered with weaker candidates unable to make sufficient number of relevant points, or not focusing effectively on urban air pollution as opposed to other forms of pollution.
\nOften this was well-answered by candidates with even the weaker candidate able to gain some credit for identifying valid factors influencing energy choices. Full credit was generally limited by candidates not having named case studies or failing to specifically address “changes” in energy choice.
\nFigure 3(a): Population and land information
\nIdentify the most densely populated country in Figure 3(a).
\nPhilippines;
\n[1]
\nThe majority of candidates correctly answered the question. The most common incorrect response was Indonesia.
\nFigure 3(b): Age-gender pyramids for Indonesia and Timor-Leste
\nWith reference to Figure 3(b), outline two reasons for differences between the age-gender pyramids for Indonesia and Timor-Leste.
\nIndonesia has a declining birth/fertility rate due to increase in female empowerment/equality/education/later marriages / Timor-Leste has a high birth/fertility rate due to less access to education for women;
Indonesia has a declining birth/fertility rate due to access to contraception/family planning / Timor-Leste has higher birth/fertility rates due to lack of access to contraception/family planning;
Indonesia has lower infant/child mortality/lower death rates/higher life expectancy due to improvements/access to medicine/public health / Timor-Leste has high death rates/low life expectancy due to limited access to healthcare;
Indonesia has increasing urbanization/migration from rural areas to cities which results in a lower birth rate / Timor-Leste has a high birth rate due to large rural population where children are required to work in agriculture/support parents/religious/cultural reasons;
Indonesia has introduced population policies/publicity campaigns to reduce fertility rates;
age-gender pyramid for Indonesia is in millions whereas for Timor-Leste it is in thousand because of differences in population size;
Do not accept statements without accompanying reason eg “Indonesia has a high life expectancy.”
\nDo not accept “Timor-Leste is a less developed country / Indonesia is more developed / stage of demographic model” as a reason.
\nDo not accept “Indonesia has greater land which allows for a larger population/Timor-Leste has smaller land area which accounts for smaller population”.
\nDo not accept only “healthier lifestyle / medical status”.
\n[2 max]
\nFew candidates achieved full marks for this question. Many responses only gave a description of the age-gender pyramid or focused on birth rate and death rate without giving specific reasons for the differences observed. Some responses only stated the reasons but did not outline the actual differences between the pyramids.
\nFigure 4(a): Species within the Coral Triangle
\nWith reference to the data in Figure 4(a), calculate the percentage of the world’s coral species found in the Coral Triangle.
\n() = 75.81 (%) / 75.8 (%) / 76 (%)
\n[1]
\nThe majority of candidates calculated percentage correctly. A few rounded the answer incorrectly and there appeared to be some candidates who did not have a calculator and struggled with the calculation.
\nFigure 4(b): Coral reef fish diversity
\nFigure 4(c): Global distribution and species diversity of corals, mangroves and seagrasses
\nWith reference to Figures 4(b) and 4(c), suggest how fish diversity may be influenced by the habitat diversity of the Coral Triangle.
\nhigh diversity of habitats/variety of habitats provide a variety of niches that supports high fish diversity / high diversity of habitats/seagrass/corals/mangroves leads to high diversity of fish;
variety of habitats provide different food sources that support a wide range of fish species;
variety of habitats provide different breeding/nursery grounds for diversity of fish;
variety of habitats provide different shelter/protection from predators which increases fish diversity;
Accept converse statements eg fewer niches outside coral triangle result in less fish diversity.
\nAccept use of “animal diversity” as an alternative for “fish diversity”.
\nDo not accept ‘availability of resources’.
\n[2 max]
\nMost candidates only achieved one out of two marks by recognising that fish diversity would be high when habitat diversity is high. Very few candidates were able to provide a reason for this.
\nFigure 4(d): Example of a Coral Triangle marine food web
\nWith reference to Figure 4(d), suggest the impact on the marine food web if tuna numbers were to decline.
\nreduction in sharks/marlin (predators) of the tuna (due to reduction in food source);
increase in micronekton/predatory fish (prey) of the tuna (due to reduction in predation);
reduction in phytoplankton/mesoplankton/microplankton due to increase in micronekton population;
loss of tuna reduces competition for food (micronekton/predatory fish) resulting in overall increase in sharks/marlin population;
to compensate for loss of tuna, shark/marlin eat more micronekton/predatory fish resulting in overall decline of micronekton/predatory fish population;
to compensate for loss of tuna, shark/marlin eat more micronekton/predatory fish resulting in an increase in phytoplankton/mesozooplankton/microzooplankton population;
Accept other reasonable responses.
\nDo not credit the same marking point twice eg reduction in sharks and reduction in marlin.
\nDo not accept only “collapse of marine food web” or “reduction in biodiversity”.
\n[2 max]
\nThis question was answered well by most candidates. Common errors included: (i) only stating changes in feeding behaviour but not how this affects the population numbers; (ii) misinterpreting the direction of the errors.
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nOutline one advantage for local populations within the Coral Triangle in harvesting their food from the marine system.
\nOutline one advantage for local populations within the Coral Triangle in harvesting their food from terrestrial agriculture.
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nit does not occupy land (needed for population / housing / wilderness area) / less deforestation;
fewer resources/inputs required / it is cheap/free (if harvested themselves);
there is natural income available (if harvested sustainably)/annual yield from natural capital;
it satisfies cultural preferences;
diverse range of species/food available (within Coral Triangle);
high in nutrients/protein/essential minerals such as iodine;
weather events (droughts/floods/hurricanes) are less likely to destroy food sources;
Accept other reasonable responses.
\nDo not accept “more carbon stored / improves water quality”.
\nDo not accept only “provides source of fish/shellfish/profit / rarity of fish / high value of fish / is a healthier food supply / biodiverse ecosystem / easy accessible / no transport cost / is replenishable / increase in diversity of species”.
\n[1 max]
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\n\n
production is more efficient because of less loss of light energy;
it is more efficient because food chain is shorter / more efficient as food is harvested from lower trophic level;
it is more readily harvested because it is less dispersed;
easier to harvest / less dangerous / requires less equipment;
greater diversity of food products/crops / people decide what to grow;
reduces threat to marine habitats from overfishing / reduces damage to marine ecosystems from fishing / reduces overfishing rates / conserving marine ecosystems can make them more attractive for recreational use/tourism;
good growing condition in the area for crop growth / high levels of insolation and rainfall (tropical conditions) in the area promote rapid crop growth;
\n
Accept other reasonable responses.
\nDo not accept “absorbs/stores carbon dioxide / contains large number of nutrients”.
\nDo not accept only “sell goods”.
\n[1 max]
\nThe responses for this question were very mixed with popular responses including ‘diverse range of species/food available’ and ‘high in nutrients/protein’.
\nOverall, this question was poorly answered. A significant number of candidates did not attempt to answer it. A few candidates confused aquaculture with agriculture. Few students stated that production is more efficient as food is harvested from a lower trophic level (less loss of energy).
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nExplain two ways in which mangroves improve the water quality for primary producers within marine ecosystems.
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\n\n
Max [2] for each effect and corresponding explanation.
\nMax [2] if only explanations are stated.
\nAward mark for the explanation even if corresponding effect is wrong/too vague/absent.
\nDo not credit effect if explanation is incorrect (eg prevents eutrophication because mangroves absorb carbon dioxide and release oxygen).
\nDo not accept just “improves/maintains water quality”.
\nDo not accept just “increase/decrease in water turbidity/clarity” without explaining the corresponding effects
\nDo not accept just “reduces coastal erosion” without link to increased sedimentation.
\nDo not accept responses that explain how consumers would benefit.
\n[4 max]
\nMost candidates achieved some marks for this question. Many responses included the explanation but not the corresponding effects for example, they recognised mangroves trapped sediments but did not link this to water clarity, light penetration and improved photosynthesis for primary producers. Some candidates did not recognise the question was asking about producers, which do not require additional oxygen from mangroves to survive.
\nFigure 5: Ecosystem goods and services in coastal marine habitats
\nWith reference to Figure 5, describe how loss of a coral reef ecosystem could impact a neighbouring seagrass community.
\nwould reduce protection from waves/currents/storms / increase in damage to seagrass community from waves/currents/storms;
could reduce food source for some seagrass species;
could reduce spawning areas/nursery grounds for some seagrass species;
could increase/decrease predation pressure on seagrass species from other marine species;
without coral to filter the water, the water clarity would decline adversely affecting seagrass / an increase in water turbidity, making it difficult for light fixation/photosynthesis by seagrass;
loss of coral reefs will reduce tourism to the area thereby reducing funds available for protection of seagrass ecosystems;
Do not accept only “there is loss of biodiversity”.
\nDo not accept only “increase/decrease in water turbidity/clarity” without impact on seagrass.
\n[2 max]
\nFew candidates achieved 2 marks, most responses only considered one way in which a loss of coral reef would impact a seagrass community. A common error was to discuss the role of coral reef but not what would happen to seagrass in the absence of coral reefs. Some candidates incorrectly stated that the organisms from the coral reef would simply relocate to the seagrass ecosystem.
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nOutline two possible effects of climate change on marine coastal ecosystems within the Coral Triangle.
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nhigher water temperatures could lead to coral bleaching/death;
higher water temperatures could change migration patterns of some species/cause some species to migrate to cooler water;
higher water temperatures could adversely affect reproduction of some species;
higher water temperatures leads to loss of biodiversity because some species are unable to adapt/have a very narrow acceptable temperature range;
higher water temperatures decreases dissolved oxygen levels resulting in death of fish;
higher temperatures could increase gross primary productivity/warm water species;
higher temperatures can cause mangroves to dry out that reduce habitat for some species;
ocean acidification/lower water pH adversely affects calcifying species/shellfish/corals/calcareous plankton;
more intense/frequency of storms/currents could damage coral reefs/seagrass/mangroves /coastal ecosystems;
sea-level rise could reduce (shallow water) conditions required for mangroves/corals/seagrasses / sea-level rise could flood mangrove ecosystem;
sea-level rise could increase coastal erosion / sea-level rise could increase sediment flow into the ocean reducing light penetration/primary production within marine coastal ecosystems;
increase in precipitation could lower the water salinity that can adversely affect some species / lower precipitation could increase water salinity that can adversely affect some species;
Do not accept only “WWF predictions” without reference to specific factor altered by climate change that leads to specified impact on ecosystems within Coral Triangle.
\nDo not accept only ‘climate change / change in temperature’.
\nN.B “Higher temperature” is acceptable for “higher water temperature”.
\n[2 max]
\nThere were some excellent responses. Some responses lacked the detail necessary, e.g. referring to climate change in general or to changes in either water pH or temperature without reference to direction of change. A few responses incorrectly suggested a decrease in global temperatures and associated colder climate.
\nFigure 6: Carbon storage in different ecosystems
\nSome ecosystems are very effective at absorbing carbon dioxide from the atmosphere and storing this carbon either within their living biomass or in the soil below ground.
\nWith reference to Figure 6, outline the effectiveness of mangroves and tropical rainforests in the mitigation of climate change.
\nmangroves/tropical rainforest mitigate climate change/reduce CO2 in the atmosphere by absorbing CO2;
mangroves sequester/remove a greater amount of CO2 (per unit area) than the other ecosystems/tropical forest / mangroves are more efficient at storing carbon than tropical forests / mangroves are more effective carbon sinks than tropical forests;
tropical forest hold more carbon in their living biomass / mangroves hold more carbon in the soil;
both tropical rainforest and mangroves store the highest amount of CO2 within their living biomass for their own ecosystem category;
mangroves hold approximately 1500 metric ton carbon per hectare / tropical forest hold approx 230 metric ton carbon per hectare;
tropical forests may remove less CO2 per unit area but occupy a far greater area globally / mangroves remove more CO2 per unit area but occupy less area globally;
Accept quantification without units.
\n[2 max]
\nThis question was fairly well answered by most candidates who were able to successfully interpret the data given.
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nExplain how the following land-based activities could have a damaging effect on marine ecosystems within the Coral Triangle: deforestation.
\nExplain how the following land-based activities could have a damaging effect on marine ecosystems within the Coral Triangle: agricultural activity.
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nAward [1] for identifying the problem, and [1] for explaining its effect on marine ecosystems.
\nDo not accept just “soil/coastal erosion” without link to increased sedimentation.
\n[2 max]
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nAward [1] for identifying the problem, and [1] for explaining its effect on marine ecosystems.
\nDo not accept loss of mangroves and its associated effects.
\nDo not accept just “overgrazing causes soil erosion” without link to increased sedimentation.
\n[2 max]
\nFew candidates achieved full marks for this question. Many struggled to link deforestation on land with an impact on marine ecosystems. Common error was to use generic terms such as ‘pollution’ and not name the specific type of pollutant.
\nThis question better answered than Q11a. Many candidates correctly identified fertilizer runoff as causing problems of eutrophication. Common error was to discuss the removal of mangroves rather than focusing specifically on agricultural activity.
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nSuggest two strategies that could be used to reduce the threat to coral reefs from tourism.
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nreduce/restrict tourist numbers/boat numbers / use daily quotas for visitor numbers;
ban littering/waste disposal in the threatened areas / develop recycling programs for plastic waste / fine tourist for littering;
ban individual collection of souvenirs/shells/corals/fish / ban and police trade in threatened species / enforce CITES regulations on protected coral species;
restrict boat speed to reduce damage to wildlife;
restrict areas (spatially/temporally) used for boating/by tourists (tourism zones);
ban diving/snorkelling without qualified guide who ensures appropriate behaviour that limits damage to the coral reef;
anchor boats in designated areas/area fitted with a mooring buoy / restrict number of boats allowed to anchor in designated areas;
develop non-intrusive interaction with marine life eg glass bottom of boat to view marine life / apply restrictions on following distances for whales/marine species;
conduct education awareness programmes/advertising to educate tourists on appropriate way to interact with wildlife/coral ecosystems;
build/invest in sewage treatment systems (to reduce BOD and suspended solids of effluent released into coastal environment);
Accept other reasonable responses.
\nDo not accept only “ban diving/snorkelling / use MPAs/LMMAS/no-take zones / legislation that prohibits any damage to coral reefs”.
\n[2 max]
\nThis question was well answered by the majority of candidates. Some responses lacked the necessary detail for credit, e.g. they stated ‘reduce pollution’ without specifying type of pollution and how it could be reduced.
\nFigure 8(a): Conservation within the Coral Triangle
\n[Source: adapted from www.coraltriangleinitiative.org; http://wwf.panda.org]
\nWith reference to Figure 8(a), outline two advantages of Locally Managed Marine Areas (LMMAs) for providing effective conservation of marine systems.
\nengages the local community that directly impacts the systems / can more effectively raise local awareness/encourage change in behaviour / encourages more people to be involved / provides “ownership” to locals to engender responsibility / managed by communities that cares about the project/want to help;
can be more flexible responding to specific threats/crises/local conditions;
locals are knowledgeable about the area;
can be less bureaucratic / allow for faster response / allows closer monitoring;
will provide more efficient policing / enforce policies in a way that fits the local custom;
Do not accept “no take zones / tourism zones / use of traditional fishing methods / increase in fish size/fish numbers/biodiversity / employment”.
\n[2 max]
\nMany candidates incorrectly answered this question often referring to key features of Marine Protected Areas rather than focusing on what is unique to and therefore an advantage of Locally Managed Marine Areas.
\nFigure 8(d): Drop in demand for shark fins in Hong Kong and mainland China
\nConservation efforts have also focused on reducing trade of wildlife parts such as shark fins.
\nIdentify one way in which conservation efforts may have given rise to the decline in shark fin imports shown in Figure 8(d).
\nuse of education/media/raising awareness to influence consumers’ values/tastes (to reduce demand);
ban on trade in wildlife parts (increasing their protection/making them less available);
establishment of reserves where shark fishing is banned (increasing their protection/reducing their availability);
greater/more efficient policing of poaching in reserve areas;
growing demand in shark tourism means sharks are worth more alive to local communities;
Do not accept only “efforts to reduce trade in shark fins” without how this is being achieved (eg education/legislation/bans).
\nDo not accept “less sharks are captured” without explaining why (eg reserves that ban shark fishing).
\nDo not accept “tariffs on shark fin imports”.
\nDo not accept only “fishing is limited/restricted / CTI-CFF agreement” .
\n[1 max]
\nMany candidates gave good focused responses. Common error was to give vague statements such as ‘efforts to reduce trade in shark fins’ without suggesting how it was being achieved (e.g. via legislation that banned trade).
\nThe resource booklet provides information on the Coral Triangle. Use the resource booklet and your own studies to answer the following.
\nWith reference to data throughout the resource booklet, to what extent would the establishment of Marine Protected Areas (MPAs) benefit marine ecosystems and human societies within the Coral Triangle?
\nThis question requires “Resource Booklet - May 2019 SL paper 1”, available under the \"your tests\" tab > supplemental materials.
\nMerits – [4 max]:
MPAs are supported by legislation and associated enforcement powers;
MPA could provide nursery/breeding ground for species /sanctuary for some species/protect species from human activities / MPAs stop reduction in fish stocks through fishing activities / by restricting tourism to certain areas MPAs can reduce damage caused by tourism to reef ecosystems;
…this could allow recovery of threatened species/range of species/ biodiversity;
MPA would lead to increase in population of species that could provide food;
MPA would lead to increase in population of species that could provide an income avenue for local people/sustainable livelihood;
species from MPA could move/migrate and allow for increase in biodiversity in surrounding areas;
increase in regional biodiversity could lead to increase in ecotourism that provides an alternative income for local communities;
improvements in marine ecosystems/increase in mangroves/seagrasses can enhance carbon dioxide sequestered from the atmosphere / improvements in mangroves/seagrasses can increase carbon storage, contributing to the mitigation of climate change;
within MPAs the increase in mangroves/seagrasses/coral filters the water and removes pollutants in the marine environment;
MPAs help to meet our moral/ethical obligation to conserve/protect species / MPAs help to meet our duty to conserve our environment for future generations;
improvements in coastal ecosystems can help to protect coastal communities from extreme storm events/coastal flooding;
increase in mangroves/seagrasses population can improve water quality for other primary producers/coral reefs;
MPA creates jobs for local people and an alternative income;
MPAs allow some restricted fishing to meet the needs of local people;
Limitations – [4 max]:
establishing MPAs could cause areas surrounding them to be over-exploited / many areas still adversely affected by fishing/human activities;
difficult to stop people fishing/using areas that have been traditionally used;
difficult to stop illegal fishing by non-local vessels;
without effective policing/enforcement is unlikely to work;
some species population may have fallen below recovery levels;
MPAs can in the short-term lead to loss of income/resources / maybe difficult to find alternative income/food source in the short term for local people;
in the short-term local communities may require support to consider other ways to earn money/obtain food / loss/reduction in shark fin trade results in loss of income for fishers;
local community needs to be educated on value of MPAs;
local community needs to be educated/trained on how to sustainably fish stocks outside the MPAs;
as MPAs are managed by government (not local community) there may be a lot of bureaucracy involved and management of MPA may be inefficient / may take time to reach a consensus before action can be implemented / corruption may be an issue leading to inefficient management of MPA;
difficult to manage/balance interests of so many stakeholders (ie six countries, local governments, NGOs etc.);
predicted loss of coral by 2050 is a result of global warming, which will not be stopped by protecting local areas;
with increase in tourism there may be increased pollution caused by waste/plastics resulting in decrease in biodiversity;
with population growth in the area and associated increase in food demand the restriction in fishing within MPAs will cause human hardship;
Award [5 max] for merits and limitations.
\nConclusion/opinion [1 max]
For example: over the long term MPAs can be effective at improving biodiversity/state of the ecosystem and sustainable resources for local people although in the short term they can pose many difficulties/hardships for local communities (without appropriate support);
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument) and supported by evidence. Do not credit the conclusion if only one side of the argument has been considered within the overall response.
\nAccept other reasonable responses supported by information in the resource booklet.
\n[6 max]
\nMost candidates achieved some marks for this question, with many obtaining between 2 to 4 marks. Common error was to discuss only the merits of using MPAs and not include any limitations. In addition, few accounts gave a balanced conclusion that addressed both sides of the argument.
\nFigure 1: Stages of succession following disturbance by fire
\nOutline two reasons why the species within pioneer communities in Figure 1 are more likely to be r-strategists than K-strategists.
\nOutline two reasons why the climax community in Figure 1 is more stable than the intermediate community.
\nDistinguish between zonation and succession.
\nOutline two ways in which the food web is likely to change as a result of succession.
\nOutline two ways in which the soil quality in the pioneer stages of the succession model shown in Figure 1 will differ from that in the climax ecosystem.
\nr-strategists produce greater numbers/many offspring/fast population growth;
r-strategists distribute themselves more widely/colonize more quickly;
r-strategists mature quickly/reproduce earlier/establish themselves faster;
r-strategists better adapted to harsh/low-nutrient conditions/less specialised niches;
Do not accept just ANY valid characteristic of r-strategists (eg short life-span) ...only those directly relevant to a pioneer community as above.
\n[2 max]
\ngreater number of species/habitat/ecological niches/genetic diversity in climax community;
gross productivity/stored biomass is higher in climax community;
more complex/diverse energy pathways/food webs;
more established nutrient cycling;
more favourable abiotic conditions/soil properties;
more established negative feedback mechanisms;
[2 max]
\nsuccession is the process of changes in community/ecosystem over time, whereas zonation is the process of changes over an environmental gradient/space;
\n[1]
\nincreasing numbers of trophic levels / longer food chains;
will be composed of new/different species;
more branching / greater complexity / more species at each trophic level;
greater gross productivity/energy transferred at each trophic level;
more biomass stored at each trophic level;
increased prominence of decomposer community;
[2]
\nIn pioneer communities...
there will be lower organic content/leaf litter (due to combustion from the fire);
there may be a higher concentration of available minerals (released from ashes);
there may be fewer soil organisms (following deaths from fire);
it will be more prone to erosion/evaporation losses (through lack of vegetation cover/roots by fire);
less established nutrient recycling / reduced decomposer community;
Accept converse of these statements for climax community.
Note: The model shows SECONDARY succession (after fire), so not all generic features of a pioneer community in PRIMARY succession would be valid. eg in primary succession soil nutrients may be higher in climax community, but in secondary succession reverse is more likely (although processes of nutrient cycling/decomposition may still be more advanced established in climax community as in primary succession).
[2 max]
\nMost were able to give one relevant feature of r strategists.
\nMost were able to give one feature of a climax community contributing to its stability.
\nProbably around half the candidates were sufficiently familiar with both concepts to clearly distinguish zonation from succession.
\nMost were able to give one way in which food webs change.
\nMany candidates failed to appreciate this was an example of secondary succession and hence, although organic matter may be low in pioneer soils, mineral content would be high.
\nFigure 2: Methods of domestic waste disposal for selected countries
\nWith reference to Figure 2, state the country that has the highest level of recycling/composting.
\nOutline two possible reasons for greater use of landfills in the United States compared with the European countries shown in Figure 2.
\nOutline two strategies for reducing the environmental impact of landfill sites.
\nIdentify two problems associated with one of the waste disposal choices of Germany.
\nAustria;
\n[1]
\nmore available land in USA / less available land in Europe;
high cost/privatisation of recycling in USA / more subsidies for recycling in Europe;
limited domestic technology for recycling established / dependence on export of recyclables in USA;
in Europe, a stronger environmental education/commitment/more ecocentric EVS;
EU laws/regulations may penalise landfill use/promote alternative disposal;
[2]
\nreducing waste/employing alternative disposal methods;
collection of methane / management to prevent spontaneous ignition;
extraction/treatment of leachates;
use of impermeable liner/clay/materials / locating above impermeable rock;
locating away from surface and groundwater sources/residential areas/vulnerable or valuable ecosystems;
visual screening to reduce impact of eyesore/aesthetic degradation OWTTE;
effective cover/containment system to prevent plastics/lightweight materials blowing into environment;
limiting transport distance/emissions from collecting vehicles;
densely compacting solid waste before dumping;
[2 max]
\nALTERNATIVE 1: Waste to energy (through incineration/biogas):
emissions from combustion/anaerobic digestion can be toxic/release GHGs/add to air pollution;
still require disposal of solid waste/ash; requires technology/infrastructure which could be expensive/not cost-effective;
public opposition due to noise/smell/aesthetics/perceived health threats/impact on property prices;
may reduce public incentive to reduce waste;
ALTERNATIVE 2: Recycling/composting:
recycling can be energy intensive;
recycling requires technology which could be expensive;
emissions from recycling process/unaerated composting could release GHGs etc;
limited range of products can be effectively recycled/composted (inappropriate materials/poor sorting/condition);
requires political will/civil management/public collaboration;
recycling can degrade materials;
composting may lead to bacterial/fungal infections / leachates/run-off contaminating soil/water;
may be public opposition to smell of composting;
may reduce public incentive to reduce waste;
Award [1 max] if chosen method is not identified. If both choices (i.e. “waste to energy” AND “recycling/composting” are addressed only credit the higher scoring one).
\n[2 max]
\nVast majority gained credit for this with just the occasional erroneous response of “Australia”.
\nMany correctly suggested more available land in US but quite a few suggested greater quantity of waste/population which wouldn’t in itself explain the greater percentage use of landfills.
\nMost were able to suggest one strategy for reducing impact of landfills.
\nMost were able to identify disadvantages of either ‘waste to energy’ or ‘recycling/composting’.
\nFigure 3: Tropospheric ozone levels in Mexico City
\nWith reference to Figure 3, calculate the difference between the highest concentration and lowest concentration of tropospheric ozone.
\nState two factors necessary for the chemical formation of ozone in the troposphere.
\nOutline why a high concentration of ozone in the troposphere is a direct problem for humans, while in the stratosphere it is a benefit to humans.
\nSuggest possible reasons for the overall trends of tropospheric ozone levels in Figure 3.
\n(peak of 175 – lowest point of 73 =) 102 (ppb);
\nAccept 72 – 75 as lowest point, ie 100–103 (ppb).
\nUnits and working are NOT required for the 1 mark.
\n[1]
\nsunlight/UV light;
NOx/oxygen (atoms/ free radicals/molecules)/hydrocarbons/VOCs;
Note: Only credit necessary reactants for ozone formation as shown above. Do not credit sources of these active pollutants (eg fossil fuel use, organic solvents, pesticides etc).
\n[2]
\nin the troposphere it causes respiratory illnesses / eye/nose/throat irritations / heart failure;
\nin the stratosphere it prevents entry of UV that is harmful to humans/can cause mutations/skin cancer/tissue damage/cataracts/crop damage; [1 max]
\nNote: Do not credit responses that simply suggest global warming/climate change as an impact of tropospheric ozone without referring to some direct impact of those phenomena on humans.
\nNote: Accept “ozone in stratosphere protects humans from UV” WTTE … (use of “protects humans” implies UV is harmful to humans).
\n[2]
\nin first few years, increase due to:
from around 1991 onwards, a decline may be due to:
\nAward [3 max] if only discussing decline or only discussing increase or failing to specifically identify either decline or increase.
\n[4 max]
\nMost were able to extract and calculate data with sufficient accuracy.
\nMany were able to suggest two factors though a good number forgot sunlight/UV. There were also some confused responses suggesting CFCs/refrigerants.
\nMostly correct, with occasional confusion of stratospheric/tropospheric ozone.
\nThere were a good number of candidates mistakenly addressing stratospheric ozone issues, i.e. CFCs/ODSs/Montreal Protocol etc. Those that were on the right track frequently scored 2 or 3 of the available marks, though rarely all 4.
\nWith reference to processes occurring within the atmospheric system identify two transformations of matter.
\nWith reference to processes occurring within the atmospheric system identify two transfers of energy.
\nExplain how regional differences in the hydrological cycle influence the formation of different biomes.
\nClimate can both influence, and be influenced by, terrestrial food production systems.
\nTo what extent can terrestrial food production strategies contribute to a sustainable equilibrium in this relationship?
\ncondensation; evaporation; freezing; melting;
\nO3 → O2 + O; Cl + O3 → ClO + O2; SO3 + H2O → H2SO4; NOx + H2O → HNO3;
\nAccept other reasonable responses.
\nAccept any valid chemical changes identified by formulae or words (eg decomposition of ozone).
\n[2 max]
\nradiation of sunlight/solar energy/heat/light toward earth;
radiation of heat/IR away from earth;
reflection of light/heat toward space from earth/clouds;
scattering of light/heat from particulate matter;
movement of (sensible) heat pole-wards by wind currents/tricellular winds/Hadley Cell/hurricanes/tropical cyclones;
movement of latent heat in water vapour by winds;
[2 max]
\nin certain tropical regions there is high transpiration/precipitation;
…allowing for high productivity/tropical rainforests;
in other tropical regions evaporation exceeds precipitation;
…so, water is limiting for growth leading to vegetation of desert biomes;
in polar regions large proportion of water is frozen/stored as ice/glaciers;
…so unavailable to plants resulting in limited vegetation of tundra;
in mid-latitudes there is moderate transpiration/precipitation;
…allowing for moderate plant growth of temperate grasslands/forests;
in regions where water inputs exceed outputs/surface topography promotes rise of water table;
...water accumulates above the soil to form an aquatic system/wetland;
mountainous regions cause variations in precipitation on leeward/windward sides;
...may cause forest growth on windward side/drier desert-like communities on leeward;
Credit can be given for responses that identify features of hydrological cycle characteristic of a given region OR how such a characteristic gives rise to a given biome.
\nAward [3 max] if the characteristics are not directly linked to given biomes.
\n[7 max]
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\n[9]
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nMost candidates were able to identify two transformations of matter.
\nFew candidates were able to identify transfers of energy in the atmosphere …often referring instead to energy transfers in food chains or transfers of matter.
\nMost candidates were able to gain three or four marks through addressing precipitation in rainforests and deserts, but few went further than this.
\nResponses often addressed either impact of climate on agriculture or vice versa, limiting range and balance of argument. A good number also addressed sustainable agricultural practices quite unrelated to climate.
\nIdentify four impacts on an ecosystem that may result from the introduction of an invasive species of herbivore.
\nExplain how both positive and negative feedback mechanisms may play a role in producing a typical S population growth curve for a species.
\nTechnocentrists may support the belief that technological development has always been able to overcome limits to human population growth.
\nTo what extent do the patterns of growth and development in human populations, as demonstrated in the Demographic Transition Model, support this claim?
\nreduction in plant species (through feeding);
…(causing) reduction in overall productivity;
reduction/loss of native herbivore species (through competition);
…(causing) reduction/loss of carnivore species/higher trophic levels;
…(causing) reduction in species diversity;
shift of equilibrium/toward tipping point;
introduction of new diseases/pathogens/parasites (carried by invasive species);
in some circumstances may benefit ecosystem by eg increasing food for higher trophic levels/increasing diversity;
[4 max]
\npositive feedback will occur at start of S curve where numbers are small;
\nAward [3 max] for following marking points as statements OR shown in a diagram. See example below:
as populations increase/reproduce they increase the number of reproducing individuals;
…which will further increase the growth rate;
ie positive feedback …a change promoting further change in same direction;
negative feedback occurs as graph approaches maximum/carrying capacity/plateau;
\n\n
Award [3 max] for following marking points as statements OR shown in a diagram. See example below:
Limiting / density dependent factors / predation/food/water availability/disease;
…will become increasingly limiting, reducing growth rate;
…stabilizing population at around carrying capacity
ie negative feedback …a change leading to reduction of further change;
Award [3 max] if responses do not clearly identify +ve and -ve feedback.
\n[7 max]
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\n[9]
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nGreat majority scored some credit, usually for addressing depletion of plants and outcompeting other herbivores … but few went on to consider further impacts of these phenomena and so were limited to two marks.
\nMany candidates scored some credit here, though usually rather precariously through identifying some limiting factor or describing predator–prey relationships, but rarely with a sound understanding of the role of positive and negative feedback in population growth curves.
\nMany candidates could identify ways in which medical/agricultural technology are significant in overcoming limits to growth during early development but few acknowledged opposing influences later on, or related their response very directly to all stages of the DTM.
\nIdentify four strategies for limiting the impact of burning fossil fuels without reducing their use.
\nSuggest a range of practical procedures that could be carried out to measure the abiotic and biotic impacts of an oil spill in an aquatic ecosystem.
\nEven though there is growing global support for ecocentric values, the global consumption of fossil fuels continues to rise each year.
\nWith reference to energy choices in named countries, discuss possible reasons for this situation occurring.
\nuse of scrubbers on factories/power plants;
use of catalytic converters on vehicles;
regulating quality of exhaust gases;
using low sulphur coal resources;
restoring ecosystems damaged by pollutants / eg liming of acidified lakes;
sequestration/CCS;
afforestation/reforestation/reducing deforestation;
masks reducing inhalation of toxic gases/emissions;
building of sea defences;
vaccination/anti-malarial programmes;
Credit any responses identifying other valid strategies that don’t involve reducing fossil fuel use. Do not credit “increasing efficiency of vehicles/machinery using fossil fuels” ...these will only limit impact by reducing consumption, which is explicitly excluded by question.
\n[4 max]
\nidentify a transect / sampling scheme to compare conditions over time/distance;
carry out multiple samples at each site to ensure reliability;
measure oil content/concentration using chemical tests;
measure light penetration using Secchi disc;
(use appropriate probes/meters/logging devices) to measure temperature/oxygen concentration/pH/salinity;
measure change in O2 concentration of samples kept in dark as a measure of BOD;
sample invertebrate populations using kick samples/Eckman grab/water samples;
Lincoln Index/mark-release-recapture may be used to quantify fish/larger invertebrates;
identify species present and abundance of each;
use this to calculate a biotic index evaluating sensitivity/tolerance of species present;
use similar data to calculate diversity with a diversity index;
count total numbers of birds/fish etc clearly impacted/killed by oil;
Credit any other procedures of equivalent detail and validity to those given above.
No additional credit for evaluating procedures/discussing impacts.
If response simply indicates measuring a named abiotic factor they can be credited for MP5 but can only gain one mark in total for any number of such factors. To gain further credit for other abiotic factors they should indicate some detail of the procedure beyond simple use of a probe/meter/logging device.
Award [4 max] for responses that address only biotic or only abiotic impacts.
\n[7 max]
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\n[9 max]
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nMany candidates were able to identify appropriate strategies to reduce impacts without reducing the use of fossil fuels although these were often mixed with inappropriate strategies that did imply reduced use of the fuels.
\nResponses often failed to score well because they just listed factors that could be measured or described how they might be affected, but gave minimal or no practical details of how they could be measured.
\nMany candidates approached this question well, discussing difficulties with alternative fuels and economic and political pressures for the continued use of fossil fuels. Weaker responses had few relevant and specific examples and a limited range of different reasons for the paradox.
\nIdentify four factors that make the estimation of carrying capacity more problematic for human populations than for most other species.
\nExplain why the ecological footprint of two populations consuming the same quantity of food and energy may be different.
\nDiscuss the potential for designing a protected forest area that allows for the harvesting of natural resources while at the same time conserving its biodiversity.
\nHumans:
\n[4 max]
\na population may consume the same as another but produce more (for export or just wasted) which will increase its EF/require more land;
food production systems may be different in terms of efficiency / sustainability;
…some may be more intensive / use advanced technology / fertilisers;
…or rely less heavily on meat products / more heavily on vegetarian products;
…or be located in a climate more favourable to food production;
…and therefore, produce same quantity of food with less land/lower EF;
energy production may rely more heavily on renewable sources/solar energy/hydroelectricity/wind power;
…or be located in regions with higher rates of primary productivity/photosynthesis;
…employ more effective mitigation strategies;
…so, absorb carbon wastes with less local land/lower EF;
activities other than food and energy provision may influence ecological footprint (eg urbanization/water pollution);
one population may lack treatment facilities / regulations for wastewater leading to greater EF;
one population may live in multistory buildings / smaller houses using less land so lower EF;
Note: Question addresses difference in footprints between populations not per capita footprints.
\nAward [4 max] for responses that address only food or only energy production OR for responses that make no reference to actual difference in EF or land required.
\n[7 max]
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\n[9 max]
\nRefer to paper 2 markbands, available under the \"your tests\" tab > supplemental materials.
\nMany candidates gained a mark or two here for mentioning diversity in lifestyles or technological developments but many responses were too vague or addressed irrelevancies of population demographics.
\nMost candidates were able to identify differences in diet and energy sources but few were able to identify other factors affecting ecological footprints. Some addressed irrelevancies of population sizes.
\nResponses tended to show either some understanding of principles of design for protected areas or of principles for sustainable harvesting, but rarely both.
\nOutline one method for measuring the impact of a build-up of dead organic matter in an aquatic ecosystem.
\nExplain how models of ecosystems might be used in species conservation.
\nDiscuss how the introduction and re-introduction of a species can affect an ecosystem.
\nNotes: Credit can be similarly awarded for impacts on other valid components of ecosystem e.g. turbidity / dissolved O2.
If candidate addresses more than one method then only give credit for most high scoring.
Notes: Award [2 max] for valid named examples of ecosystem models e.g. food chains / webs / pyramids / systems diagrams / flow charts / aquaria / zoos / microcosms / biodiversity indices / computer programmes / mathematical models.
Credit can be given for any of the following ways in which models may assist conservation:
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nNot many responses went beyond measuring oxygen as an indication of organic water pollution. Most responses had no practical details of procedure.
\nGreat majority of candidates were unable to identify examples of ecosystem models (food chains/pyramids/flow charts/aquaria/indices/computer models, etc.) so answers were very vague.
\nCandidates appeared very familiar with issues of introduced species but had little to add when it came to issue of reintroduction.
\nOutline the albedo effect and its role in regulating the Earth’s global temperature.
\nCompare and contrast the adaptation strategies to climate change for two societies.
\nDiscuss whether biodiversity loss or climate change is a greater threat to human societies.
\nNote: Accept alternative feedback loops.
\nThe following adaptation strategies can be credited provided it is clear whether they are common to both societies (compare) or are a point of difference (contrast).
\nweather readiness…
\nNotes: Award [5 max] if only compare or only contrast used.
Award [3 max] if strategies are simply described but not clearly compared or contrasted between two named societies.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMost candidates had some valid idea of albedo and its role in temperature regulation.
\nA large proportion of candidates mistook mitigation strategies for adaptation and so failed to gain significant credit.
\nGenerally well answered, although weaker candidates failed to explore the full scope of the question.
\nFigure 4(a): Average net primary productivity (kJ m–2 a–1) of selected world biomes
\n[Source: graphic used with the permission of Integrated Access STEM Sites, LLC]
\nFigure 5(b): Water-surface temperature variation across the Large Ocean Management Area
\n[Source: Fisheries and Oceans Canada. Reproduced with the permission of
© Her Majesty the Queen in Right of Canada, 2019]
Using Figure 4(a), identify an ecosystem that has an average net primary productivity above 30 000 kJ m–2 a–1.
\nSuggest one reason for the zonation seen in Figure 5(b).
\nEstuaries are one of the most productive ecosystems in the world, but only account for 3 % of global productivity.
\nState one reason why this occurs.
\nOutline why estuaries are highly productive ecosystems.
\nestuary/tropical rainforest.
\ndepth of water / shallow water is warmer / shallow water is easier to warm up / deep water is cooler;
position in relation to land / distance from land;
latitude / distance from equator / northern areas are cooler / southern areas are warmer;
cold ocean currents (Labrador) coming down from the north and warm ocean currents (Gulf Stream) coming up from the south.
Do not accept ‘climate change / global warming / variation in climate / salinity /temperature’.
\nthere are few major estuaries in the world;
they do not cover much of the Earth’s surface;
estuaries have quite a small surface area;
they represent a small proportion of the world’s ecosystems.
mix of saline and fresh water so different habitats, therefore more biodiversity, (therefore more productivity);
zonation/range of temperature/salinity results in greater habitat diversity (therefore higher productivity);
shallow water, so warmer and receive more light and therefore more productive (primary productivity);
tides/river systems/upwellings bring in nutrients that give rise to phytoplankton blooms/primary productivity;
mineral/nutrient run-off from surrounding agricultural land / nutrient run-off from surrounding watershed into the estuary;
water levels rise and fall, exposing mud flats, which are a food source for shore birds (secondary productivity);
migratory birds and whales stop here to feed, temporarily raising the secondary productivity.
Do not accept only ‘high biodiversity’.
Do not accept only ‘large/complex food webs’.
Identify four strategies that can be used in the sustainable management of wild fisheries.
\nEvaluate the sustainability of two water management strategies to improve access to freshwater resources in a society.
\nTo what extent can the different environmental value systems improve the sustainability of food production?
\nExamples of strategies [2 max]:
\nThe following examples of water management strategies and their evaluation show how credit can be given for any appropriate strategy.
\nExample 1: Rainwater harvesting;
Positive:
does not impact natural water cycle / replenishment rate / impossible to reduce natural income;
free natural capital;
useful for watering plants/irrigation / washing / fire protection / (thus) reduces consumption of groundwater/other freshwater resources;
Negative:
availability restricted temporally and spatially (unequal distribution of rain / unpredictable supply);
usually not safe for drinking;
can’t satisfy needs of irrigation of commercial agriculture;
Example 2: Desalinization;
Positive:
sustainable if energy required produced by photovoltaic cells;
sea water is more available than freshwater;
provides accessible/safe drinking/irrigation water;
salt may be used for producing useful chemical products (sodium hydroxide, hydrochloric acid);
reduces pressure on freshwater reserves that need protection;
Negative:
requires huge amounts of energy / increase GCC if fossil fuel used;
not available in landlocked countries;
building of facilities result in environmental damage/pollution;
disposing of salt (brine) poses environmental hazards/pollutes ocean / salt is contaminated so can’t be eaten;
high cost to build and operate that may be economically unsustainable;
Notes: Award [1 mark] for each appropriately identified strategy for improving access to freshwater up to [2 max].
Do not accept simplistic statements not clearly linked to sustainability, e.g. cheap / efficient / doesn’t need elaborate equipment/scientific expertise.
Accept statements such as “its cost is too great to be economically sustainable / its cost may divert economic resources away from habitat/species protection / resource requirement maybe unsustainable for LEDCs”.
Award [5 max] if only positive OR only negative evaluation OR only one strategy evaluated.
Award [1 max] for each clear negative or positive evaluation of each factor.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nNote: IB considers anthropocentrism as “humans sustainably managing global system” (through regulations/policies/incentives etc.) rather than the common dictionary definition that it means simply “humans are the central/most significant entities in the world” leading to an understanding of the EVS as cornucopian (which it isn’t necessarily). Responses addressing anthropocentrism should be evaluated in this light.
\nMost candidates were able to identify several strategies for sustainable management of wild fisheries, although a few mistakenly addressed aquacultural systems.
\nMajority of candidates were able to describe two water management strategies but often failed to evaluate their sustainability in any detail.
\nCharacterisation of value systems tended to be simplistic/inaccurate particularly in the distinctive features of anthropocentrism. However, a good range of food production strategies was offered.
\nFigure 1: Management of solid domestic waste in England, 2001–2018
\n[Source: Statistics on waste managed by local authorities in England in 2017/18, Department for Environment, Food and
Rural Affairs. Source adapted.]
With reference to Figure 1, identify the recycling rate in England in 2018.
\nOutline one reason for the shape of the recycling rate curve from 2013 to 2018.
\nEstimate the reduction in solid domestic waste (in million tonnes) going to landfill from 2001 to 2018.
\nDescribe three reasons why the proportion of solid domestic waste being recycled/ composted and incinerated has changed.
\nOutline one reason why there has been an overall change in recorded total solid domestic waste between 2001 and 2018.
\n44 %;
\nNote: Accept 43 %–45 %
\nCurve has flattened between 2013–18 due to:
only certain types of waste are recyclable;
limited market for recyclable materials/goods (OWTTE);
difficult to change human behaviour completely;
recycling facilities/ability may have reached full capacity (OWTTE);
Note: Accept other valid reasons for the plateau — do not credit responses that explain why it has increased.
\n(22 − 4 =)
~18 (million tonnes);
Note: Accept 16–19 (million tonnes); do not accept percentage (e.g. 18 %)
\npublic awareness campaigns/government legislation/education promoting recycling/incineration;
meeting international agreements/quotas/obligations;
lack of space / suitable sites for landfill;
to reduce environmental impacts of landfill (e.g. leachates/landfill gas/habitat destruction/ pests/vermin);
developing technology/facilities for recycling/for energy production;
increasing need for renewable/cleaner energy sources;
financial reward/incentive for energy production;
Note: Avoid double marking (sim) where responses give similar reasons for both recycling/composting and incineration (e.g. more efficient than landfill)
\nThere has been an overall decrease in total solid waste due to:
government promotion/incentives for reuse/upcycling;
economic changes leading to reduced consumption;
greater awareness of environmental issues leading to less wasteful consumerism;
changes/errors in methods of data collection;
reduction in amount of packaging;
reduction in production/use of single-use items;
Note: Credit any valid reason for a decrease in total waste. (Do not credit ‘increase in recycling’ as recycling is included in SDW in the graphic ...but reuse or upcycling is OK)
\nMost were able to read the recycling rate from the graph but a significant number used the wrong axis.
\nMost were able to recognise the curve was reaching a plateau and explained how the rate was being limited although some simply explained why recycling had increased which was not required.
\nMost were able to calculate the reduction in landfill waste although, again, there was some confusion over which axis to use, and how to interpret the stacked histograms.
\nThis was well-answered with many candidates coming up with three different influences causing the increase in recycling and incineration.
\nA good number of candidates were able to see that re-use and reduced consumption were most likely to have caused the decline in overall SDW.
\nFigure 4(a): Population pyramid for Dominica, 2018
\n[Source: CIA, 2018. The World Factbook: Dominica. Available at: https://www.cia.gov/library/publications/the-worldfactbook/
geos/do.html.]
Figure 4(b): Population statistics for Dominica, 2017
\nAfter the hurricane, thousands of men and women left Dominica in search of work. With reference to Figure 4(a), draw a post-hurricane age–gender pyramid for Dominica to illustrate this outward migration.
\nWith reference to Figures 4(a) and 4(b), suggest how population change may impact resource use on Dominica in the future.
\nNote: (see sketch) [1] for basic shape, stage 3 characteristics with axes and labels (must include labels for age group and gender)
\nconcave sides in the working age groups;
may have greater outward migration in the male working age side;
may have slight reduction in youngest group to show reduction in birth rates due to loss of fertile adults;
population is stabilizing/growth rate is slowing, so there will be little additional demand for resources;
population will begin to age so demand for resources will decrease due to fewer children;
birth rates are still high in comparison to death rates so the population is still growing, putting pressure on resources;
stabilizing population will lead to greater prosperity and therefore greater demand for resources;
outward migration means less demand for resources;
development of tourist industry/temporary immigration causes increase in use of some resources, eg water, land for hotels;
Note: Do not credit only ‘increase in population results in an increase in resource use / decrease in population reduces resource use’.
\nThe drawings varied widely from rough outlines to more detailed figures. Many candidates recognised that migration would result in a loss of working age population, although figures often lacked the required labels for each axis. A significant number of candidates did not attempt this question.
\nMost responses lacked the detail required for credit. Many candidates did not use the information in the resource booklet to suggest a reason for why the population may change. Some responses focused on changes in resource availability rather than use of resources.
\nFigure 5: “Building back better”
\n[Source: Gemma Handy.]
\nDominica is focusing on a “Building back better” programme of recovery after Hurricane Maria to:
\n[Source: United Nations Development Programme - UNDP Barbados & the Eastern Caribbean.]
\nUsing information from Figure 5, outline how the “Build back better” programme can contribute to the resilience of Dominica.
\nresilience refers to a system’s return to equilibrium after a disturbance which relates to how quickly Dominica is rebuilding infrastructure/replanting/repairing;
conducting disaster risk assessment before reconstruction ensures that buildings are not placed in areas at risk from future hurricanes/landslides;
building hurricane-proof buildings reduces damage from future hurricanes;
planting fast-growing crops ensures agriculture/food supplies can recover quickly from damage in the future / planting fast growing crops reduces risk of soil erosion;
planting heat-tolerant varieties of food/putting animals in air-conditioned buildings means that rising temperatures from global warming will not negatively affect food supplies/agriculture;
focusing on root crops means food supplies are protected from strong winds;
using local skills and resources allows Dominica to be self-reliant without the need to import goods/skills potentially leading to a faster/cheaper recovery;
community participation in reconstruction which encourages ownership of project/takes into account local conditions is more likely to be successful;
Note: Connection must be made to resilience. Do not award marks for simply repeating material in the Resource Booklet.
\nAlthough most candidates achieved some marks for this question, few achieved all 3 marks. Many responses lacked the detail necessary for credit and a number of responses repeated information given in Figure 5 without outlining how these aspects would contribute to resilience.
\nThe resource booklet provides information on Dominica. Use the resource booklet and your own studies to answer the following.
\nDiscuss the effect of hurricanes on the social and ecological development of Dominica.
\nThis question requires “Resource booklet-November 2020 SL Paper 1” available under the “your tests” tab > supplemental materials.
\nDetrimental [4 max]:
destruction of corals and therefore reduction in biodiversity and/or productivity;
destruction of mangroves/rainforest and therefore reduction in biodiversity and/or productivity/further reductions in numbers of endangered species;
contamination of freshwater ponds/lakes/wetlands and reduction in biodiversity;
flooding washes toxic chemicals and sewage into the oceans, contaminating reefs;
salinization of the soil through saltwater incursion and reduction in productivity;
destruction of habitat/food resources for animals;
destruction of reefs/coastal wetlands, deltas, etc. which make the coastline more vulnerable to future tropical storms;
increase in food insecurity/malnutrition as food crops destroyed;
loss of jobs for people in agriculture leading to increased poverty;
lack of food/poverty may lead to people hunting for bush meat/selling endangered parrots for the pet trade, reducing biodiversity;
poverty/loss of infrastructure may result in people cutting down trees in reserve areas for fuelwood;
increased poverty on the island may reduce the protection provided to endangered species;
outward migration (of working age population) due to lack of employment/fear of another hurricane results in separation of families/falling birth rates/ageing population left behind who cannot work/increase in dependent population;
re-building puts a strain on natural resources including forest for building materials;
cost of re-building puts a strain on economic development / rebuilding places an economic burden on society;
Not detrimental [4 max]:
natural process and ecosystems are adapted to hurricanes and/or recover /damage is temporary;
opens up forest canopy to allow new growth/secondary succession which increases productivity;
allows for better rebuilding to reduce damage in the future;
draws community together in the rebuilding process;
increase in local businesses as foreign companies leave due to danger;
changes physical geography of the land, creating new habitats;
brings in cooler water, reducing risk of coral bleaching;
Note: award [5 max] for both detrimental and not detrimental marking points.
\nConclusion [1 max]
Conclusion must be balanced
eg In the long-term ecological development may be more adversely affected than social development, as some species may become extinct whereas plans to help rebuild Dominica may lead to a more cohesive society;
Most candidates achieved some marks for this question. Some candidates gave detailed responses that correctly addressed the question. However, some responses incorrectly focused on economic development instead of social and ecological development. Few candidates provided a balanced conclusion.
\nFigure 1: Demographic transition model
\n[Source: CIA, 2018. World Factbook: Costa Rica. Available at:
https://www.cia.gov/library/publications/resources/the-world-factbook/geos/cs.html.]
Costa Rica has a crude birth rate (CBR) of 15.3 and a crude death rate (CDR) of 4.8. Identify the stage in which Costa Rica would be placed on the demographic transition model shown in Figure 1.
\nCosta Rica has a crude birth rate (CBR) of 15.3 and a crude death rate (CDR) of 4.8. Calculate the natural increase rate (NIR) for Costa Rica.
\nCosta Rica has a crude birth rate (CBR) of 15.3 and a crude death rate (CDR) of 4.8. Calculate the doubling time for Costa Rica.
\nOutline one strength and one limitation of the demographic transition model.
\nOutline the socioeconomic factors that may cause a society to move from Stage 2 to Stage 3 on the demographic transition model.
\nstage 3;
\nNIR = 1.05;
\nNote: As there is some disagreement in the literature, accept 10.5 (per thousand)
\ndoubling time (DT) =
\nDT = 66.67 years;
\nNote: Accept 67 years, but do not credit unless units are given.
\nStrength [1 max]:
provides a theoretical basis for comparing other societies;
can be applied to a wide range of societies;
allows predictions to be made regarding transitions / population growth;
it is based on historical data;
indicates relationship between multiple factors;
Weakness [1 max]:
many assumptions are made to make the model / relationships are quite simplistic;
Eurocentric model might not apply to all countries;
does not take into account events such as migration/war/rapid spread of disease that may have limited impact on populations;
decreasing birth rate/ fertility/growth / smaller families due to:
\ncontinued decreasing death rate due to:
\nNote: Must link answer to decreasing birth rate and/or decreasing death rate to earn mark.
\nAward [2] max if candidate addresses only birth rate or only death rate.
\nMost were able to identify the stage of demographic transition.
\nMost were able to calculate NIR.
\nVery few knew how to calculate doubling times for a population.
\nMost were able to identify a strength of the model but few identified a realistic weakness.
\nMost could identify a couple of factors that would facilitate a shift into stage 3 but very few gained the full 3 marks available.
\nFigure 2: Distribution of continents and diversity of species over time
\n[Source: Biodiversity (in thousands of genera) since the Cambrian explosion of evolution, https://commons.wikimedia.org/wiki/File:Phanerozoic_Biodiversity.svg. This file is licensed under the Creative Commons Attribution-Share Alike
3.0 Unported license. (CC BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.en.
USGS (United States Geological Survey) maps at https://pubs.usgs.gov/gip/dynamic/historical.html
From This Dynamic Earth: The Story of Plate Tectonics by W. Jacquelyne Kious and Robert I. Tilling
Public Domain.]
With reference to Figure 2, identify when the diversity of species was lowest in the past 400 million years.
\nDescribe what may have caused the deviation from the trend line at point X in Figure 2.
\nIdentify the relationship between the number of continents and the diversity of species during the past 250 million years.
\nDescribe two reasons why there is a relationship between the number of continents and the diversity of species.
\nOutline the role of natural selection in increasing the diversity of species.
\naround 250 million years ago/Ma/Mya;
\nNote: Accept 240–255 Mya.
Do not credit if units (million years/Mya) are not given.
mass extinction/extinction event / mass extinction of dinosaurs (65 Mya);
due to meteor/asteroid impact / volcanic activity / climatic change / ice age;
the greater the number of continents, the greater the diversity / positive correlation (OWTTE);
\nseparation of continents isolates populations leading to (allopatric) speciation;
continents are moved into different climatic regions causing evolution of different species;
continental movement creates new habitats, e.g. mountain ranges/islands;
natural selection (resulting from changing environment) acts on existing genetic variation (that has arisen through mutations over the eons);
natural selection increases the survival of fittest genetic variations/traits;
these traits are heritable/passed onto offspring / selected individuals will have higher reproduction potential / so species will adapt to different environments;
the proportion of these traits may increase in some populations/in subsequent generations;
which can lead to speciation/increasing species diversity if there is reproductive isolation;
Most were able to identify the lowest point on the species diversity curve. There were some careless responses that failed to acknowledge the figures represented millions of years.
\nMost were able to recognise a mass extinction and offer a reasonable cause.
\nThe great majority could identify the simple positive correlation. Those that missed it got caught up in complex attempts at explanation (required in the next question) and failed to clearly identify the key relationship.
\nA good number were able to identify either geographical isolation or climate diversity as a key reason ... a few were able to offer both appropriate reasons.
\nMany candidates struggled to write accurately about natural selection often referring to species mating with other species and similar confusions.
\nFigure 6(c): A simplified food web for the St Lawrence River beluga whale
\n[Source: Halibut image: FishWatch.gov
Phytoplankton: GreenVector/VectorStock
Zooplankton: macrovector/VectorStock]
Figure 7: Estimated population of the St Lawrence River beluga whales
\n[Source: An age-structured Bayesian population model for St. Lawrence Estuary beluga (Delphinapterus leucas), Canadian
Science Advisory Secretariat (CSAS) Research Document 2013/127, Quebec Region. Fisheries and Oceans Canada.
Reproduced with the permission of © Her Majesty the Queen in Right of Canada, 2019]
Figure 6(b): Fact file on the beluga whale (Delphinapterus leucas)
\nFigure 8: Threats to the St Lawrence River beluga whale
\nShipping and whale watching:
\nHunting:
\nPollution:
\nUsing Figure 6(c), identify a food chain in the St Lawrence River ecosystem that has five trophic levels.
\nUsing Figure 7, state the St Lawrence beluga whale population in 1920 and 1940.
\n1920:
\n1940:
\nCalculate the percent decrease in beluga whale numbers from 1920 to 1940.
\nWith reference to Figure 8, explain why the beluga whale is more at risk from toxic pollutants, such as heavy metals and persistent organic pollutants (POPs), than most other organisms in its food web.
\nSuggest why the St Lawrence River beluga whale population has not recovered despite being given protected status in 1983.
\nResponse should indicate the flow of energy from phytoplankton to beluga whale (e.g. using arrows in the correct direction or words indicating what is eating what).
For beluga whale accept either beluga or whale.
Do not accept a food chain that includes sun/light.
1920: accept 6000–6300;
1940: 2000.
Both responses required for [1].
\n\n
Accept answers between 66.67 % and 68.25 %. Also accept 66.6 recurring.
Accept answers between –66.67 % and –68.25 % (as it is a percentage decrease).
Units are not required.
Only the final answer is required for [1].
Do not accept 66 %/66.6 % (incorrect rounding).
these are persistent toxins that build up in the fatty tissues (and beluga whales have 40–50 % body fat);
they are at the top of the food chain (biomagnification along the food chain);
bioaccumulation over a long life span;
increasing concentration of pollutants (bioaccumulation) within the species consumed by the whale;
persistent pollutants accumulate along the food chain due to decrease of biomass and energy;
eat benthic feeders, which assimilate toxins by scavenging corpses of marine organisms;
Do not accept just the terms ‘biomagnification/bioaccumulation’.
\nisolation is leading to genetic diversity loss and lowered resistance to disease;
small population size may affect reproductive rate / low genetic diversity may affect the reproductive rate;
slow development / late to reach sexual maturity / produce only a low number of offspring;
pollutants bioaccumulating in fatty tissues interfere with successful reproduction;
high levels of pollutants still found in their habitat, impacting their ability to reproduce effectively / industrial effluent discharges may kill/harm whales / pollutants could adversely affect food supply of the whale;
shipping causes separation of mother from calf (increasing number of calf deaths);
ships/human activities produce noise that interferes with feeding behaviour/reproduction in whales;
water temperatures rising, moving outside tolerance of beluga whale food source, reducing food availability;
invasive species may reduce food available for beluga whale;
despite being protected, may get caught in commercial fishing nets and drown;
may be killed in collisions with boats, as the St Lawrence River is an important shipping route;
commercial fishing removing food source / competition for food with commercial fisheries;
there may be illegal hunting of beluga whales.
Do not accept only ‘threat of pollution / hunting / due to sport fishing / K-selected species and therefore slow to recover’.
\nFigure 10(a): Recycling rates in London and England, 2000–2015
\n[Source: Greater London Authority, 2016. Draft Economic Evidence Base 2016. [online] Available at: https://www.london.
gov.uk/sites/default/files/draft-eeb-2016.pdf [Accessed 1 June 2020].]
\n
Figure 10(b): Proportions of material recycled in London, 2006
\nWith reference to Figures 10(a) and 10(b), suggest one reason why London’s recycling rates are lower than in the rest of England.
\nEvaluate the effectiveness of recycling as a waste management strategy for London
\nNote: Do not accept only ‘London has a large population / people refuse to recycle / harder for people in London to recycle / London produces a lot of waste’.
\nEffective [2 max]:
\nConclusion [1 max] needs to be balanced considering both sides of the argument for credit.
\nNote: Conclusion is not mandatory and [3] marks can be achieved through consideration of both pros and cons.
\nThere were very mixed responses to this question. A common error was to suggest that due to the high population in London more waste was generated rather than focusing on why the recycling rate was lower.
\nMost candidates achieved at least one mark for this question by recognising that the current rate of recycling was relatively low. Very few students achieved three marks.
\nFigure 2: Representation of the water cycle
\n[Source: © International Baccalaureate Organization 2020.]
\nIdentify one transfer and one transformation process shown in Figure 2.
\nTransfer:
\n\n
Transformation:
\n\n
Outline how urbanization might impact two of the storages in Figure 2.
\n\n
Runoff from agricultural land can result in excess nutrients entering water bodies. Outline one indirect measure of organic pollution.
\nRunoff from agricultural land can result in excess nutrients entering water bodies. State one management strategy that could control the release of agricultural runoff.
\ntransfer:
advection/precipitation/snowmelt runoff/surface run off/infiltration/percolation/groundwater flow/plant uptake;
transformation:
evaporation/condensation/sublimation/snowmelt/transpiration;
Note: Only credit those flows identified in diagram.
\nreduction in biomass storage due to deforestation;
reduction of groundwater storage due to impermeable surfaces/urban withdrawal;
increase in lake/river/ocean storage due to deforestation/increase of impermeable surfaces;
less snow due to urban heat island effects;
increased sediment/pollution in lakes/rivers/oceans/groundwater due to construction/industrialized activities;
Note: Credit can be given for any aspect of urbanisation (deforestation/heat island/impermeable surface etc) with a relevant impact on a named storage that is depicted in given diagram. Only credit impacts on storages not on flows.
\nAlternative 1:
Named measure [1 max]:
biochemical oxygen demand;
Methodology [2 max]:
measure the initial dissolved oxygen;
keep a sample in the dark for five days and measure DO again;
take the difference of the two measurements;
Alternative 2:
Named measure [1 max]:
biotic index/indicator species;
Methodology [2 max]:
sample the macroinvertebrates in the stream/lake;
through kick sampling/dragging feet along bottom;
identify species present;
identify indicator species/tolerance levels;
Note: Do not credit any direct measure of pollutant like total suspended matter/turbidity etc.
\nplant a buffer zone;
reduce the use of inorganic fertilizers / replace their use with organic fertilisers;
do not apply fertilizers in the rainy season;
keep animals away from waterways;
treat livestock wastewater (to reduce phosphates and nitrates);
contour ploughing/terracing/agroforestry/drip irrigation (to avoid run off);
Vast majority were able to identify a valid transfer and transformation process.
\nA good number were mistaken in identifying impacts on flows of the system rather than storages.
\nMany failed to identify an indirect means of measuring organic pollution and, of those that did, very few could give details of the procedure.
\nMost were able to identify a strategy for reducing agricultural runoff.
\nRefer to the information provided in the resource booklet in your answer.
\nTo what extent is London a sustainable city?
\nThis question requires “Resource booklet-Nov 2021 SL Paper 1” available under the “your tests” tab > supplemental materials.
\nSustainable [4 max]:
\nConclusion [1 max]: While many aspects of the urban management of London contribute to its sustainability such as use of vertical farming that helps to conserve water, the vast population in a relatively small area means that its environmental footprint far exceeds the area of the city.
\nNotes: Do not credit ‘EF of London is greater than world average EF’.
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument), supported by evidence and makes a clear value judgement.
Do not credit the conclusion if only one side of the argument has been considered within the overall response.
Award [5 max] for both sustainable and non-sustainable reasons.
Most candidates achieved at least two marks for this question by accurately interpreting information in the Resource Booklet that could either contribute to or hinder London being a sustainable city. Responses were generally well structured. However, few students provided a well balanced conclusion. Many conclusions were either one sided or too vague.
\nFigure 1(a): Savanna food chain
[Source: Djsudermann, 2019. [Elephants in the Savannah] [image online] Available at: https://pixabay.com/photos/
elephant-trees-savannah-sky-animal-4121954/ [Accessed 29 September 2020]. Source adapted.
designerpoint, 2012. Lion-wildcat-safari-africa-515030. [image online] Available at: https://pixabay.com/photos/
lion-wildcat-safari-africa-515030/ [Accessed 3 September 2020].]
Figure 1(b): Biting flies in the savanna
\nBiting flies bite and drink the blood of zebras. They commonly carry diseases that can be fatal to zebras.
\n\n
[Source: [Tsetse fly] 2006. [image online] Available at: https://commons.wikimedia.org/wiki/File:Tsetse_fly.png [Accessed 22
May 2020]. Source adapted.
Wellcome Material: Tropical Medicine, 2014. Illustration of ‘Tabinus socius’. [image online] Available at:
https://commons.wikimedia.org/wiki/File:Illustration_of_%27Tabinus_socius%27;_Tropical_Medicine_Wellcome_
L0025345.jpg. Second report of the Wellcome Research Laboratories at the Gordon Memorial College, Khartoum
/ Andrew Balfour. https://wellcomecollection.org/works/ez3txjfg. Attribution 4.0 International (CC BY 4.0)
https://creativecommons.org/licenses/by/4.0/deed.en [Accessed 22 May 2020]. Source adapted.]
State the trophic level of the zebra.
\nState how you could determine gross secondary productivity of the zebra.
\nExplain how the second law of thermodynamics applies to this food chain.
\nState the type of relationship that exists between biting flies and the zebra.
\nZebra stripes may reduce the ability of the biting flies to land on the zebra. Describe how natural selection may have led to the evolution of zebra stripes in response to biting flies.
\nprimary consumer/herbivore/second trophic level;
\nmeasure the mass of food that the zebra eats and measure the mass of the fecal loss;
GSP is the difference between food consumed & fecal loss/GSP = food eaten − fecal loss;
parasitism / predation / carnivory / disease vector;
\nNote: Award [2 max] if not related to biting flies.
\nVery well answered.
\nGreat majority were unable to identify how gross secondary productivity is measured.
\nMany were able to suggest some appropriate application of the second law of thermodynamics to a food chain.
\nGenerally well answered.
\nMajority were at least able to begin explaining the process of natural selection in this context.
\nFigure 9(a): Fact file on the round goby (Neogobius melanostomus)
\nFigure 9(b): Pictures of the round goby and mottled sculpin
\nUsing Figures 9(a) and 9(b), identify one feature of the round goby that shows it is an r-selected species.
\nWith reference to Figure 9(a), outline how the round goby both positively and negatively affects the St Lawrence River ecosystem.
\nWith reference to Figure 9(a), explain why the realized niche of the mottled sculpin has changed in recent years.
\nfrequent egg laying (3 times per year);
many eggs laid at one time (5000);
young fish grow quickly / early maturity.
Positive [2 max]:
provide additional food source for native fish (e.g. yellow perch);
eat other invasive species, such as the zebra mussel.
Negative [2 max]:
increased competition for food, outcompeting native fish;
outcompetes the native mottle sculpin for the best egg-laying sites;
outcompetes native species which may become extinct;
eat other fish eggs, reducing populations/biodiversity;
introduce disease, reducing populations/biodiversity.
Accept any other reasonable response.
Do not accept only ‘outcompetes native species’, for credit must be linked to competition for food, egg laying sites or species extinction.
Do not accept ‘aggressively takes the habitat of native species’.
resources declined due to competition with round goby;
competition for/loss of nesting sites;
loss of food resources due to additional competition;
realized niche has changed because of impacts of climate change affecting temperature.
Figure 3: Examples of entanglement of marine species
\n[Source: NOAA.]
\nFigure 4: Sea turtle species and their status from the IUCN Red List
\nCalculate the percentage of sea turtle species from Figure 4 that are critically endangered.
\nState two factors that are used to determine the conservation status of a species.
\nIdentify two strategies for fisheries management that could improve the conservation status of sea turtles.
\nDiscuss how solid domestic waste disposal options could be used to reduce the threats to marine organisms.
\n= 28.6 %
\nNote: Accept 28.57 / 28.6 / 29.
\npopulation size;
rate of pop increase/decrease;
degree of specialization;
distribution;
reproductive potential and behaviour;
geographic range;
habitat quality/fragmentation;
trophic level;
probability of extinction;
restrict use of fishing nets/long lines;
bycatch reduction strategies;
establish marine protected areas/exclusion zones / police/implement laws against poaching/overexploitation;
replace wild fisheries with aquaculture;
ensuring fishing nets/lines are not lost at sea / reduce ghost/abandoned/lost nets/lines / OWTTE;
Note: Award [1] for any of following arguments or counterarguments (…)
\nRecycling can reduce plastics entering waterways;
...but is costly/depends on changing lifestyles;
Landfill can reduce wastes entering waterways;
...but can still lead to leaching of toxins into aquatic environments;
Incineration can reduce wastes entering aquatic environments;
...but may cause air pollution and deposition/acidification of marine environments;
Composting can reduce organic waste polluting waterways;
...but is only suitable for biodegradable waste;
Littering laws can reduce waste entering marine systems
…but need appropriate penalties/monitoring etc;
Conclusion
e.g. recycling is probably the most reliable protection of marine organisms against plastic waste;
Note: Award [3] max if neither counterarguments nor conclusion are presented I.e. response must include at least one or the other to fulfil the ‘Discuss’ command term.
\nMost were able to calculate this simple percentage.
\nMost were able to identify two criteria for assessing conservation status of a species.
\nMany were able to come up with a suitable fishing strategy for conserving turtles but few gave a second strategy for full credit.
\nMany were able to identify appropriate strategies for solid waste disposal but generally they failed to \"discuss\" such strategies i.e. identify strengths/weaknesses or argue for and against.
\nFigure 10: Untreated sewage release into the St Lawrence River
\nMontreal:
In November 2015, the City of Montreal discharged between 5 and 8 billion litres of untreated sewage into the St Lawrence River.
Quebec:
In November 2016, the City of Quebec discharged 110 million litres of untreated sewage into the St Lawrence River.
Nationally:
\n[Source: adapted from www.cbc.ca/news]
\nFigure 11(a) and (b): Coliform bacteria concentrations (in units/100 mL) in the
St Lawrence River near Montreal
Figure 11(a): Before the release of untreated sewage
\nFigure 11(b): One day after the release of untreated sewage
\n[Source: adapted from CBC news, © OpenStreetMap contributors www.openstreetmap.org/copyright and © Mapbox.
Data adapted from Ville de Montréal the open data portal http://donnees.ville.montreal.qc.ca/dataset?q=intercepteur
and licensed under CC BY 4.0 https://creativecommons.org/licenses/by/4.0/legalcode]
Using Figure 11(b), estimate the highest concentrations of coliform bacteria (in units/100 mL) found in the St Lawrence River one day after the untreated sewage was released.
\nOutline an environmental problem that may result from the release of untreated sewage into a river.
\nWith reference to Figures 10, 11(a) and 11(b), describe a method to monitor the impact of the release of untreated sewage into the St Lawrence River ecosystem.
\n120 000 (units/100 ml);
\nUnits are not required.
\neutrophication / algal bloom;
… due to high levels of nitrates and phosphates/nutrients;
hypoxic conditions;
… due to high oxygen demand;
rotten egg smell / production of hydrogen sulphide;
… due to anaerobic decomposition;
increase in micro-organisms/pathogens within shellfish;
… due to pathogens being filtered out of the water;
ill health in people / increase in waterborne disease;
...eating shellfish/fish contaminated with pathogens/bacteria (from sewage);
...from swimming in water contaminated with pathogens/bacteria (from sewage);
...drinking water contaminated with pathogens/bacteria;
death/loss of benthic species
… due to particulates blocking feeding/respiratory systems;
decrease in photosynthesis;
… due to increase in turbidity (reducing light penetration).
Accept any other reasonable response. Answer must have the named problem and the associated outline for both marks.
\nDo not accept ‘thermal pollution/increase in temperature’.
Do not accept just ‘loss of biodiversity / water unsuitable for human use’.
can use indirect or direct measures of pollution;
direct measurements of dissolved oxygen using a probe / light and dark bottle method to measure BOD / direct counts of coliform units using microscopes / Secchi disc to monitor turbidity / titration to measure changes in nitrates/phosphates;
freshwater invertebrates can be used as indicator species;
compare with historic data / take measurements before the release of the untreated sewage (for ‘normal’ measurements);
take measurements along the length of the river, from the point source downstream (to determine area impacted);
take measurements over a period of time, to observe changes in water quality.
Distinguish between two named biomes and the factors that cause their distribution.
\nEvaluate one method for measuring primary productivity in a named ecosystem.
\nDiscuss how human activities impact the flows and stores in the nitrogen cycle.
\ne.g. tundra vs tropical rainforest:
\nDistinguishing features [3 max]:
tundra has lower insolation / TRF has the highest insolation of all biomes;
TRF has constant insolation throughout the year / tundra has long, dark winters;
tundra has lower mean annual temperature / TRF has warmer temperatures;
tundra has 6–10 months of freezing temperatures / TRF has constant warm temperatures;
TRF has the largest annual precipitation compared to any biome / tundra precipitation is as low as in deserts;
TRF has almost constant precipitation throughout the year;
tundra precipitation mostly in form of snow / tundra has a characteristic layer of frozen ground below the surface/permafrost;
TRFs have the highest biodiversity of all biomes;
Explanation of distribution: [2 max]
tundra found at the poles, while TRFs at the tropics (above and below the equator);
Hadley cell rises at the Equator causing huge precipitation (low pressure zone) / as warm air cools and its moisture condenses;
tundra is found in the low pressure area of polar cell / at a region where there is net loss of solar energy (causing freezing temperatures) / alpine tundra found on mountaintops, where temperatures are below 0 most time of the year due to high altitude;
Notes: Award [3] max for correctly indentified distinguishing features i.e. insolation / temperature / precipitation / permafrost / high biodiversity etc.
Award [2] max for explanation of distribution.
Award [2] max overall if no biomes are named.
Alternative 1:
Method:
light and dark bottle for an aquatic ecosystem;
measure dissolved oxygen at start and end of experiment;
compare measurements in a transparent (with light) and opaque (without light) bottle containing sample of water from ecosystem;
net productivity is equivalent to change in dissolved oxygen in light bottle;
gross productivity is equivalent to change in dissolved oxygen in light bottle plus the loss of dissolved oxygen in the dark bottle (due to respiration);
measurements taken for a set period of time, eg one week;
Evaluation:
simple, easy to conduct method;
ethical method – samples can be returned to ecosystem;
difficult to isolate primary producers from consumers in ecosystem sample;
only collecting productivity for submerged subset of ecosystem;
measurements dependent upon temperature;
quality of measurements depends on precision of instruments;
Alternative 2:
Method:
three comparison plots, one covered in opaque plastic for terrestrial ecosystem;
measure dry biomass at start and end of experiment;
compare measurements from an open (with light) and covered (without light) plot in ecosystem;
net productivity is equivalent to change in biomass in open plot;
gross productivity is equivalent to change in biomass plus the loss of biomass in the covered plot (due to respiration);
measurements taken for a set period of time, eg one week;
Evaluation:
easy to isolate primary producers in ecosystem sample;
difficult to collect all biomass;
ethical problems as samples need to be killed to measure dry biomass;
measurements dependent upon temperature;
productivity easier to measure in simpler systems;
difficult to measure with larger producers/trees;
Notes: Award [3] max for description of method. Evaluation should address inherent strengths and weaknesses of method. Do not credit examples of poor execution eg inaccurate measurement/samples too small etc.
Award [6] max if ecosystem is not named.
No credit can be given to responses that mistakenly address eg biodiversity rather than productivity.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nQ4 was by far and away the least popular question and, when attempted, was certainly found to be the most challenging. This seemed largely because candidates did not have a clear idea of how to measure primary productivity in a system or to identify human impacts on the nitrogen cycle. Q(4) (a) Most candidates could give sufficient distinguishing features of two named biomes.
\nVery few candidates showed awareness of suitable methods for measuring primary productivity of a system and, of those that did, they tended to just describe such methods and not \"evaluate\" them.
\nIt was clear from most responses that candidates were struggling to link in many issues of atmospheric pollution, eutrophication etc to an account of the nitrogen cycle. They knew aspects of the natural cycle but seemed unfamiliar with human impacts on that cycle.
\nAn area of temperate coniferous forest was deforested and allowed to regenerate. A survey of species numbers was conducted in three successional stages. The results of the survey are summarized in Table 1.
\nTable 1: The number of organisms found in each successional stage for selected species
\nFigure 2: Keen’s mouse was found in all three successional stages
\n[Source: Stuart Wilson / Biosphoto / Alamy Stock Photo.]
\nReferring to the data in Table 1, calculate the Simpson’s diversity index (D) of the late successional stage (show your working).
\n\nDefine species diversity.
\nExplain why the diversity changes in the different successional stages.
\nState one method to determine the population size of the Keen’s mouse.
\nIdentify two factors that could impact the accuracy of the method stated in 2(d)(i).
\n;
\nNote: Award [1] for correct answer; [1 max] if no working shown;
Accept 4.96, 5.0 or 5.
Accept any valid working.
species diversity is the function of the number of species/richness and their relative proportions/abundance/evenness (in an area);
\nSpecies diversity increases toward the later stage...
\nAward [1] for stating appropriate method:
e.g. capture–mark–release–recapture / Lincoln index;
Note: Do not credit “full count/total census” or methods that would only give data of relative abundance e.g. mouse droppings.
\nNotes: Allow error carried forward (ECF) if method for 2di is wrong.
Both positive and negative impacts on accuracy would be acceptable although candidate does not need to specify which for full credit.
Some were able to correctly calculate the diversity index, though a large number failed to attempt this question.
\nFew were able to give a precise definition of species diversity.
\nMost were able to suggest one reason why diversity increases in succession but few were able to gain full credit.
\nGood number recognised Lincoln index as an appropriate method.
\nFew were able to identify factors affecting the accuracy of the method.
\nThe resource booklet provides information on St Lawrence river estuary and the Gulf of St Lawrence. Use the resource booklet and your own studies to answer the following.
\nWith reference to information in the resource booklet, evaluate the sustainability of Canada’s management of the Large Ocean Management Area of the St Lawrence River estuary and Gulf of St Lawrence.
\nThis question requires “Resource booklet-November 2019 SL Paper 1” available under the “your tests” tab > supplemental materials.
\npro-sustainable actions [4 max]
beluga whales have protected status (environmental sustainability) / management has stopped hunting of beluga whales to ensure sustainability in the area;
protected marine areas will ensure nursery areas for continued commercial fishing (environmental/economic sustainability);
protected areas can help to conserve species/biodiversity;
government is working to mitigate damage caused by shipping (reducing ship speed to avoid hitting whales) during migratory season of the right whale (environmental sustainability);
aquaculture development can reduce pressure on wild catch (environmental sustainability);
money/income from oil fields could lead to economic sustainability;
improvements in technology reduces the risk of future spills (environmental sustainability);
whale watching brings in money to local communities (economic sustainability) /activities such as whale watching encourages conservation of species/biodiversity;
commercial fishing can be sustainable with use of quotas/limitations on catch times/changes to net size to reduce bycatch (environmental sustainability);
sewage treatment from cities is in place, reducing nutrient/organic/pathogen loading in water (environmental sustainability);
government has promised $197 million into aquatic research which may lead to increased sustainable management/polices;
government has promised to protect 10 % of Canada’s coastline from fishing and drilling which could protect critical habitats/species.
non-sustainable actions [4 max]
shipping lanes go through the marine reserve in the St Lawrence River estuary, disturbing beluga/right whales;
shipping brings in invasive species which are changing the ecology of the region;
the protected areas are small and do not correspond with habitat of critically endangered right whales / protected areas do not cover entire range of beluga whales;
beluga numbers have not increased/right whales are being found dead as there is an ongoing problem/management is not effective;
contaminants from aquaculture can cause algal blooms;
species may escape from aquaculture that could adversely affect native species e.g.create competition for resources/reduce genetic diversity/transfer disease to wild populations;
whale watching can interfere/disturb organisms;
release of untreated sewage in the past has adversely affected some species/water uses / there is lack of government management in controlling discharge of untreated sewage / many people do not have access to sewage treatment resulting in the release of untreated wastewater into waterways;
government has proposed sites for oil and gas exploration/drilling which could adversely affect some species/biodiversity;
an oil spill would irreparably harm the organisms within the protected area;
use of non-renewable natural capital/fossil fuels is unsustainable due to their combustion/use resulting in release of carbon dioxide/GHGs/contributing to climate change;
mean temperatures in the Gulf are rising due to global warming;
there is a lack of strategies to deal with the impacts of climate change/global warming on the fishing industry;
no policies in place to manage pollution of POPs/microplastics/heavy metals / release of pollutants such as POPs/heavy metals is harming some species;
rate of commercial fishing which is greater than the growth rate of the fish is not sustainable / depletion of fish stocks by overfishing is not sustainable;
uncontrolled/poorly managed sport fishing could result in the reduction of some species/biodiversity.
Award [5 max] for both sustainable and non-sustainable actions.
\nConclusion [1 max]
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument), supported by evidence and makes a clear value judgement.
Do not credit the conclusion if only one side of the argument has been considered within the overall response.
Figure 1: A typical soil profile
\n[Source: adapted from WilsonBiggs/Hridith Sudev Nambiar/Wikimedia. File licensed under CC BY-SA 4.0;
https://creativecommons.org/licenses/by-sa/4.0/]
State one transfer of matter occurring within the soil profile.
\nState one transformation process occurring within the soil profile.
\nIdentify one example of an output to the atmosphere from the soil system.
\nDescribe two characteristics of soil with high primary productivity.
\nOutline two conservation methods that could be used to reduce soil erosion.
\nbiological mixing by soil animals/earthworms / leaching / seepage / capillary action / drainage / percolation / infiltration / eluviation / absorption of minerals/water by living organisms.
\nDo not accept INPUTS of matter eg precipitation, leaf litter, parent material, particle deposition or OUTPUTS of matter eg erosion; or TRANSFORMATIONS of matter eg evaporation/weathering.
\ndecomposition;
humus formation/humification of organic matter;
weathering of primary minerals/parent rock;
nutrient cycling/nitrogen fixation/nitrification/denitrification/ammonification;
evaporation;
rusting soil.
Do not accept inputs, outputs or transfers of matter or transformations that do not occur within the soil profile.
\nNitrogen (from denitrification) / water (vapour from evaporation) / heat (from radiation/conduction) / soil particles/erosion (from wind) / CO2 (from soil organism respiration) / methane (from anaerobic decomposition).
\nDo not credit the processes in brackets ... these may give rise to the outputs but are not themselves an output from the soil.
\noptimum/medium particle size / loam soils / mixed/balanced composition of sand/silt/clay;
allow good drainage/permeability/resist water-logging;
prevent excessive leaching/good water-holding capacity;
provide sufficient air space/porosity for root growth/O2 supply;
contain ample dead organic matter/humus (for decomposers);
healthy/abundant decomposing community/soil organisms;
high availability of minerals/inorganic nutrients;
appropriate pH (6.0–6.8).
Cultivation techniques:
contour ploughing with furrows following the contour lines/at right angles to the slope/to reduce runoff;
terrace farming forms a series of steps in the hillside area/to prevent run-off;
maintaining cover crops/plant roots/stubble/mixed agriculture/agroforestry to hold soil in place between harvesting;
mulching consists of applying organic material over the exposed soil / preventing surface runoff;
buffer strips/vegetative areas by watercourses to reduce run-off/water erosion;
adding soil conditioners/lime/humus/organic material/fertilizers to increase root growth/hold soil together;
wind reduction techniques, eg wind/shelter breaks to prevent wind erosion;
avoid overgrazing/over-cropping/monoculture which degrades soil texture;
zero/minimum tillage reduces soil agitation/potential for erosion;
trickle/drip irrigation reduces run-off causing erosion.
Note: As an ‘outline’ Q, response requires just a little more than just naming a technique eg ‘terrace farming involves creating steps on a hillside’ or ‘terrace farming prevents run-off’ are acceptable ...but ‘terrace farming’ alone is insufficient.
\nOutline how a positive feedback loop can impact an ecosystem.
\nCompare and contrast the impact of two named food production systems on climate change.
\nTo what extent does the development of different societies impact their choice of mitigation and adaptation strategies for climate change?
\npositive feedback loops (destabilizing) amplify changes in an ecosystem;
feedback refers to the return of part of the output from a system as input so as to affect succeeding outputs;
this drives the system towards a tipping point where a new equilibrium is adopted;
this new equilibrium may be an alternative stable state / involve collapse of original system;
eg increased global temperatures are melting permafrost, leading to the release of methane;
...which is a greenhouse gas and leads to further increases in global temperatures;
Note: Candidates may gain full credit by illustrating the principles of positive feedback by means of a diagram or well-developed example. Credit should be allowed for this.
\nnamed food production system with description; (eg Iowa corn production in mid-west USA is highly intensive, relying upon large machinery and inorganic nitrogen fertilizers)
named food production system with description; (eg rice-fish farming in China is a low-intensity system managed by human labour, with few chemical inputs)
use of machinery vs human labour, dependency on fossil fuels;
use of organic vs inorganic fertilizers, intensive energy needs of production of inorganic fertilizers/NOx released from use of inorganic fertilizers;
animal vs plant production, animals require more land use due to position in food chain;
types of greenhouse gases produced, eg both rice and animal production produce methane;
eg case study: Rice-fish farming in Thailand [1] vs cattle farming in US [1]. Both rice and cattle produce methane, a greenhouse gas [1]. Inorganic fertilisers used in cattle farming releasing nitrogen oxides into atmosphere [1]. Rice is fertilised naturally from fish faeces so has no direct impact on climate change [1]. Cattle farming involves use of heavy machinery / fossil fuels not used in rice fish farming [1]. Rice farming produces food at lower trophic level so absorbs carbon dioxide [1].
\nNotes: Award [2] max for description of food production systems.
Other points of comparison or contrast may be acceptable but must be explicitly linked to climate change in order to gain credit.
Award [4] max if only points of comparison or only points of contrast are addressed
Credit can be given for any points of comparison or contrast with regard to impact on climate change/release of greenhouse gases.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMany candidates did well on this question and understood the principle of positive feedback. A common weakness, however, was just to describe a linear sequence of disadvantageous impacts rather than an example of actual feedback.
\nMany did well on this question. Common weaknesses were not addressing sufficiently specific food production systems or misunderstanding the question to be addressing impacts OF climate change, rather than impacts ON climate change.
\nMost were able to gain some credit on this question but frequently there was a lack of accurate distinction between mitigation and adaptation strategies.
\nFigure 3(a): World population figures 1950–2019 and predictions 2020–2100
\n[Source: United Nations, 2019. World Population Prospects 2019. [image online] Available at:
https://population.un.org/wpp/Graphs/Probabilistic/POP/TOT/900 © 2019 United Nations, DESA, Population
Division. Licensed under Creative Commons license CC BY 3.0 IGO.
https://creativecommons.org/licenses/by/3.0/ United Nations, DESA, Population Division. World Population
Prospects 2019. https://population.un.org//wpp/ [Accessed 22 May 2020]. Source adapted.]
Figure 3(b): Countries and regions where population decreased
by at least one per cent between 2010 and 2019
[Source: United Nations, 2019. World Population Prospects 2019 Highlights. [PDF online] Available at:
https://population.un.org/wpp/Publications/Files/WPP2019_Highlights.pdf. Copyright © 2019 by United Nations,
made available under a Creative Commons license (CC BY 3.0 IGO)
http://creativecommons.org/licenses/by/3.0/igo [Accessed 29 September 2020]. Source adapted.]
Using Figure 3(a), identify the year in which the median prediction of the world population will reach 10 billion.
\nOutline one reason for the uncertainty in predicting the world’s population in Figure 3(a).
\nUsing Figure 3(b), identify the region that has the most countries with a decrease in the percentage change in population between 2010 and 2019.
\nOutline two factors that could contribute to a reduction in population in the countries in Figure 3(b).
\nDiscuss how a country’s stage in the demographic transition model (DTM) might influence its national population policy.
\n2055;
\nNote: Do not credit vague statements about prediction being difficult. They should identify at least one specific factor that makes it difficult. (NB Migration is irrelevant because this is global population.)
\nEurope and Northern America;
\nNote: Accept any valid factor appropriately linked to low or decreasing fertility/high or increasing mortality/emigration.
\nGeneral statement: The DTM can...
\nNote: Responses must be linked to some aspect of the DTM to gain credit (i.e. the stage, or prevailing DR/BR).
\nVery well answered.
\nMajority were able to identify one reason for uncertainty in population projections.
\nMajority were able to identify the relevant region.
\nMajority were able to suggest valid reasons for reduction in population.
\nMany were able to gain some credit in explaining link between DTM and population policies but few were able to gain full credit.
\nFigure 2: Global capture fisheries and aquaculture production
from 1991 and projected to 2025
[Source: Food and Agriculture Organization of the United Nations, 2016, FAO, The State of World Fisheries and Aquaculture.
Contributing to food security and nutrition for all, http://www.fao.org/3/a-i5555e.pdf. Reproduced with permission.]
Using Figure 2, identify one reason for the trend shown in the curve for aquaculture.
\nUsing Figure 2, identify one reason for the trend shown in the curve for capture fisheries.
\nOutline two negative environmental impacts of aquaculture.
\nDescribe two strategies for the management of sustainable capture fisheries.
\nIncreased demand for aquaculture due to: [1 max]
\nincreased human population/increased demand for more food / decrease in some capture fisheries / genetic improvements in stock / technological advances in farming / shift of diet preferences to healthier provision of protein / increased demand for fishmeal/fish oil/animal feed / economically more viable/attractive / perceived as more ecologically effective than terrestrial livestock / need for food security (especially in Asian countries).
\nReasons for increase, and reasons for less increase than aquaculture or stabilization should equally be credited [1 max]
\ncapture fisheries increased due to increased demand/human population/improved fishing technology;
capture fisheries have increased less than aquaculture/stabilized due to depleted stocks/overfishing / negative impact of climate change / marine pollution / international regulations / growth of aquaculture reducing demand / most fish grounds have no more potential for production increase / reduced cost-effectiveness.
loss/degradation of natural habitats;
disease spread through farms;
organic waste/excess food causing eutrophication/build-up of sediment/red tides;
antibiotics/chemical treatments causing pollution;
GMOs/non-indigenous species accidentally escaping, affecting the wild fish populations;
depletion of freshwater reserves/salinization/aquifer depletion.
regulation of quotas/minimum size of fish caught / harvesting less than or equal to the maximum sustainable yield (MSY);
designation of marine protected areas (exclusion zones) / limited fishing zones;
restriction on mesh size of nets/bottom-trawling/drift-netting/explosion/methods that decrease by catch/damage habitat;
restriction to fishing seasons / to let stocks recover;
international/local efforts to monitor/study fish populations and identify MSY/sustainable limits of fishing;
enforcing global treaties on sustainable practices / reducing unsustainable subsidies;
reduce marine/plastic pollution that causes fish deaths/reduces stock;
provide incentives for move toward aquaculture / reconciling the rights of various stakeholders.
Outline two factors that enable a human population to increase its local carrying capacity.
\nExplain how the growth in human population can affect local and regional water resources.
\nTo what extent would different environmental value systems be successful in reducing a society’s ecological footprint?
\nrange of resources used;
…means that a local human population can consume/exploit more resources available locally than any other species;
human ingenuity/substitution;
…means that humans are capable to find alternative resources when one is near depletion;
variations in lifestyle;
…means that people can be flexible in their mode of consumption of limited/dwindling resources;
importation of resources;
…means that a wealthy population can grow beyond the boundaries set by their local resources;
technological developments; (can be linked to all previous factors)
…allows humans to use available resources more efficiently / discover new resources / import resources from far away;
Note: Award [1] for identifying each factor and [1] for outlining how it enables increase in carrying capacity.
\ngrowing human populations result in increased need for water for domestic/drinking/cooking use;
Commercial development/industrialisation/factories increase water demand;
increasing food demand entails increased irrigation/water for crops/agriculture;
increasing populations may increase poverty and thus economic water scarcity;
areas/locations/countries that have physical water scarcity would be mostly affected;
…causing freshwater land resources (lakes, rivers) to dwindle / risking sustainability of freshwater- resources / depletion of aquifers;
…often resulting in conflict over access to water;
increased groundwater abstraction may lead to intrusion from salt water;
(increased) industrial effluents can cause water (toxic) pollution;
dam construction to meet higher demands of growing population can affect sustainability of that water source;
increasing populations can stimulate technological innovation and greater efficiency of water use / management;
The points above may be credited through a case-study eg
\ncase study: Egypt’s population is growing fast, thus increasing demand for drinking water [1]. Need for more food in a country would increase need for irrigation [1] which would cause cause reduction in groundwater [1] in a country with scarce water resources (most water comes from the Nile river) [1]. Government has constructed dams in the Nile basin, which are threatening conflict between Egypt and its neighbouring countries [1] decreasing the amount of water downstream (due to evaporation) [1: different enough from groundwater/aquifer depletion] and decreasing silt which used to fertilize plains [1: an impact on water quality].However more electricity is produced [no mark as IRRL] and provision of irrigation water is more stable/controlled (not dependent to seasonal floods) [1 for positive impact on water resources];
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nWeaker responses merely vaguely suggested an increased use of resources rather than methods of exploiting the fixed resources of an environment more efficiently/thoroughly.
\nThis question was generally well-answered with a good range of impacts on water sources and other issues of water supply.
\nMany candidates approached this question well. Weaker responses had vague or inaccurate perceptions of the different value systems and so came up with inappropriate or equally vague strategies for reducing ecological footprint.
\nOutline two factors that affect the frequency and severity of photochemical smog in an area.
\nEvaluate strategies to manage regional acid deposition using the pollution management model.
\nTo what extent have international agreements been successful in solving atmospheric air pollution and climate change?
\nsocieties with intensive fossil fuel use/industrialization;
...produce more of the primary pollutants;
high population density is characterized by car traffic/more dense use of heating;
...which increases the concentration of the primary pollutant;
local climate can have thermal inversions/lack of wind;
...that traps the smog/decreases its dispersion;
local climate with intense sunlight;
...increases photochemical reactions/increases rate of production of secondary pollutant;
topographic factors such as hills and mountains;
...can result in trapping the pollutants/reducing wind dispersion;
Notes: Award [1] max for clearly identifying each factor, and [1] max for outlining its effect on severity/ of smog:
Award [1] max if factors are simply identified by their title with no explanation eg “population density” and “topography”
Any of the points above can be equally credited if presented in the form of a case study eg Los Angeles / Mexico City, etc).
Altering human activity:
changing transportation use to reduce private transportation / increase public transportation / walking/biking;
this can be expensive due to infrastructure improvements required;
requires public buy-in / change in behaviour;
successful if a reduction in use of fossil fuels for transportation needs;
successful if good network of charging stations / footpaths/bike lanes to encourage change;
addresses root cause of pollution/prevents any damage in first place;
education of public regarding value of renewable energies/impacts of pollution;
this can influence more environmentally friendly choices;
influences attitudes/values in future generations;
but maybe the local governments/authorities that need influencing more than general public;
Controlling release of pollutant:
reduce sulphur content of fossil fuels using trading system or pollution budgets;
has proved very successful in USA where government put legislation in place to support this;
increases costs as low sulphur fuels are more expensive / requires technological investment;
use catalytic converters on car exhausts/scrubbers/CATS;
very effective at reducing nitrous oxides;
...but expensive;
use heavy metals which need to be mined;
catalysts need replacing frequently;
effective but requires investment in the technology and expensive;
switch to renewable energy sources/nuclear;
very effective as no direct emissions of NOx or SOx;
requires diversification of energy supply, which requires political will;
requires investment to support the change in energy policy;
successful when implemented with supportive legislation;
increase efficiency of power production and demand;
advantage that it reduces all pollutants associated with power production;
taxation systems and trading mechanisms;
very effective when implemented with political support;
requires improvement in public transportation infrastructure;
could be argued that not ethical as encourages trading of pollutants;
international legislation to control emissions (eg Sulphur Emissions Reduction Protocol and the Convention on Long Range Transboundary Air Pollution);
have been successful in reducing sulphur dioxide emissions;
...but led to increase in nitrous oxide production;
can be difficult to implement and monitor;
Clean-up and restoration of damaged systems:
adding limestone powder to acidified lakes;
effective and cheap solution;
but does not remove the cause of the problem;
environmental impact of mining the limestone;
restocking lakes after remediation;
needs careful management and unlikely to return the lake to the prior system;
reafforestation/replanting of damaged forests;
expensive;
takes long time for restoration;
new growth acts as effect carbon sink;
Note: Award [5] max if only one or two out of three levels of the pollution management model addressed.
Award [3] max if no evaluation points given.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMany candidates responded well to this question having clear and specific details relating to photochemical smog.
\nMost candidates had a sound grasp of the issue of acid deposition and even some strategies for addressing it. However, a large proportion of candidates simply described the strategies rather than \"evaluating\" them.
\nResponses were generally good to very good, often addressing at least three different examples of international agreements and evaluating their effectiveness with some insight.
\nFigure 3: Current and projected total fertility rates by region
\n[Source: adapted from World Resources Institute, https://www.wri.org/blog/2013/12/global-food-challenge-explained-18-
graphics. File licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)]
Using Figure 3 identify the region with the highest fertility rate in the period 2005–2010.
\nOutline two possible reasons for the projected change in total fertility rate in Sub-Saharan Africa in the period 2045–2050.
\nIdentify two reasons for the projected increase in total fertility rate in Europe by the period 2045–2050.
\nSub-Saharan Africa.
\nincreased level of education;
emancipation/empowerment/greater independence of women economically/in having children;
material ambition/increased economic cost of large families / urbanization;
decrease in need to use children for labour; (due to increased mechanization of agriculture)
(increased foreign funding toward) spread of family planning/ contraception;
reduced child mortality (due to health improvements) would allow having less children;
political decision/governmental initiatives to reduce young dependents and improve development / increased implementation of anti-natalist policies.
Note: TFR is an average figure per capita so responses making reference to overall size of population are irrelevant and should not be credited.
\npronatal policies/governmental incentives (to address economic issues/increasing dependency ratio/international competition);
eg reduced taxation/financial support for extra children;
longer maternity/paternity leave;
better day-care facilities/nurseries for infants/more flexible working hours for parents with small children;
Do not credit ‘migration’. This may affect growth rate but would have an uncertain effect on TFR (unless candidates include the conditions of the migration coming from a country with high TFR that is subsequently maintained in host-country).
\nIdentify four factors that make the use of the insecticide DDT controversial.
\nExplain how human activities continue to affect stratospheric ozone.
\nTo what extent is the use of solid domestic waste (SDW) as an energy source beneficial to a society?
\nDDT…
\nIntroductory explanations:
\nNotes: Award [5 max] if there are no explanations of “continuing” effect on ozone.
Accept CFCs as alternative to ODSs.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMajority were able to identify one or two controversial aspects of DDT although few gained full credit.
\nMajority were able to link stratospheric ozone and ozone depleting substances like CFC but frequently answers were confused with aspects of greenhouse gases and global warming.
\nMajority of answers were completely valid but rarely did they explore the question with sufficient breadth.
\nFigure 4: A measure of the sustainability of individual countries from a comparison of their ecological footprint and their standard of living
\n[Source: adapted from Travelplanner/Wikimedia. File licensed under CC BY-SA 3.0
https://creativecommons.org/licenses/by-sa/3.0/deed.en. Data sourced from Global
Footprint Network 2008 report (2005 data) and UN Human Development Index 2007/08]
Using Figure 4, identify the country that is above the threshold for high human development and below the Earth’s biocapacity.
\nOutline the relationship between carrying capacity and ecological footprint.
\nTo meet the minimum criteria for sustainability, a country needs to raise its human welfare above the threshold of high human development and have an ecological footprint below the Earth’s biocapacity.
\nEvaluate two strategies a country can implement to achieve the minimum criteria for sustainability.
\nCuba.
\necological footprint (EF) is the reciprocal/inverse of carrying capacity (CC);
populations with high per capita EF will have low CC / a population with a low EF would be less limited by CC in a given area (and vice versa) / EF determines whether a population is living within limits of CC;
EF identifies area needed (to satisfy the needs of a designated population) whereas CC identifies maximum population for sustainability (a designated area may sustain);
EF is easier to calculate but has clear implications for CC;
both EF and CC depend upon rate of resource consumption/waste produced;
both EF and CC depend upon local environmental resources/waste processing ability;
both EF and CC facilitate a quantitative assessment of sustainability;
local EF may increase by import of goods produced elsewhere, whereas CC is dependent only to local productivity / CC may decrease through export of goods;
EF is not applied to non-human populations (whereas CC is difficult to apply to human populations).
There is a huge range of potentially creditable responses/strategies for sustainability so do credit responses not listed below but of equivalent relevance and detail.
\nStrategy: reducing consumption of resources by change in lifestyle/reduced population growth/improved efficiency/imposing sustainable limits/ etc;
Advantage: addresses problem at the source / may simultaneously solve multiple problems / etc;
Disadvantage: may be unpopular / depends upon uncertain technological advance / may reduce economic development in LEDCs / etc;
Strategy: reducing pollution through reducing consumption / limiting/regulating emissions / cleaning-up/restoring polluted ecosystems / finding cleaner resources/alternatives / etc;
Advantage: some levels are more effective as they attack root of problem / helps to preserve biodiversity / reduces ecological footprint / etc;
Disadvantage: clean-up may be expensive/ineffective / regulations may hinder development / production / technological advances may not be forthcoming / etc.
Strategy: improving conservation/protection of species through conservation areas/CITES/ex-situ institutions/public campaigns/ etc;
Advantage: biodiversity is maintained improving resilience/increasing stability /potential human resources are preserved / local populations may be educated/involved / etc;
Disadvantage: ex-situ conservation does not provide full range of habitat resources/genetic diversity / conservation areas may conflict with local population needs / policing/monitoring may be ineffective / etc.
Award [3 max] if the response gives either no advantages or no disadvantages.
Award [2 max] if the response gives neither advantages nor disadvantages.
Award [0] if no strategies are identified
The figure refers to a typical Western European diet. This example shows recommended consumption of food types (on the basis of health) and the environmental impact of their production.
\nWith reference to Figures 1(a) and 1(b) state the food that has the highest environmental impact.
\nWith reference to Figures 1(a) and 1(b) state the food that has the highest recommended consumption.
\nDescribe the relationship between both pyramids in Figures 1(a) and 1(b).
\nIdentify two environmental impacts associated with producing the foods near the base of the recommended consumption pyramid (Figure 1(a)).
\nDescribe how foods high on the environmental impact pyramid, shown in Figure 1(b), are likely to affect the ecological footprint of global food production.
\nOutline two reasons why the composition of a typical diet in other regions of the world may differ from the Western European diet shown in Figure 1(a).
\nbeef;
\nfruit/vegetables;
\ngenerally, the foods with the higher level of recommended consumption have a lower environmental impact;
foods at the “top” (pictorially, rather than both apices) of both pyramids tend to be from higher trophic levels/produce a higher ecological footprint (EF) / foods at “bottom” of both pyramids tend to be from lower trophic levels/primary producers/produce a lower EF;
pyramids appear opposite to one another / have an inverse relationship/negative correlation;
use of pesticides/herbicides causing soil degradation / superbugs / superweeds;
over use of fertilizers causing soil degradation / eutrophication;
over-cultivation of land causing soil degradation;
intensive irrigation/over use of water leading to water scarcity / salinization;
mono-cropping reducing biodiversity/increasing risk of losses through disease;
use of fossil fuels through mechanization/intense farming/food miles that release GHGs/CO2;
methane released from rice-farming;
Credit can be given to any valid impact of agricultural food production.
Credit may be given for positive impacts (e.g. roots prevent soil erosion/crop rotation enriches soils) but not just the absence of negative impacts (e.g. less methane/less water, etc.)
Ecological footprint will be greater because…
higher trophic levels/more energy loss…;
…greater land area required (to produce same quantity of food);
more dependence on fossil fuels/mechanisation/food miles (+ release of GHG/CO2);
release of methane from cattle increases global greenhouse gas concentration;
higher water consumption when farming animals;
overgrazing leading to loss of arable land;
Award [1 max] if INCREASE in ecological footprint/land area required is not mentioned.
Credit may be given for any valid impact on EF due to production of food high on environmental impact (beef/pork/poultry/fish/cheese/olive oil).
Their choice may be influenced by…
traditional/cultural/religious values of certain foods;
suitability of the prevailing climate/topography/arable land;
availability of water supply;
available technology/expertise for certain cultivation techniques;
wealth / relative cost of production;
some countries/cultures may have different perceptions of what constitutes health/healthy eating;
some cultures may consider environmental impacts/have EVS that influences choice of food production;
some LEDCs may not be able to import foods so rely on more local foods;
This is a general question addressing potential factors affecting food choice; no specific examples of other diets are required for full credit.
\nVirtually all candidates were able to identify the appropriate foods.
\nVirtually all candidates were able to identify the appropriate foods.
\nMost were able to recognise one pyramid being inversely related to the other.
\nMost were able to identify potentially positive or negative impacts of agriculture, though no credit was given for identifying absence of impacts from raising livestock.
\nMost were able to give two ways in which beef farming would increase ecological footprint.
\nMost candidates were able to give at least one reason for differing food choices between countries.
\nFigure 3: Concentration of atmospheric pollutants associated
with photochemical smog
[Source: Reprinted from Environmental Pollution and Control, fourth edition, J. Jeffrey Peirce, Ruth F. Weiner and P. Aarne
Vesilind, Chapter 18 – Air Pollution, Page 253, Copyright 1998, with permission from Elsevier (http://www.elsevier.com).]
Identify one primary pollutant from the pollutants shown in Figure 3.
\nOutline why the pollutant named in Question 3 (a)(i) is referred to as a primary pollutant.
\nOutline one reason why there is an increase in nitrogen oxides and hydrocarbons early in the day.
\nExplain the changes in ozone concentration over the period shown in Figure 3.
\nState one environmental impact of the accumulation of ozone shown in Figure 3.
\nOutline two local conditions that may increase the severity of photochemical smog.
\nOutline the role of catalytic converters in reducing photochemical smog.
\nNO/NO2/hydrocarbons;
\nimpacts environment directly on emission / undergoes no chemical change before impacting environment / is active on emission;
\nNote: Even if response to 3(a)(i) is wrong full credit (ECF) can be given for appropriate definition of primary pollutant.
\nincrease in fossil fuel combustion/increased traffic/transport/industry/power plants;
\nozone is (a secondary pollutant) produced from nitrogen oxides/NOx reacting with oxygen;
it increases as more NOx accumulates in atmosphere due to human activity/fossil fuel use;
sunlight/heat catalyses this reaction so it increases towards midday;
later, ozone decreases due to dispersal by wind/less fossil fuel use/light becoming less intense;
Note: Do not credit any further detail of chemical process of ozone formation.
\ndamages plants (crops and forests) / reduces photosynthesis/plant growth;
increase susceptibility to diseases/other pollutants;
habitat deterioration;
change in water and nutrient cycles;
loss of biodiversity;
impacts human health e.g. eye irritation/respiratory illness;
damages fabrics and rubber materials;
contributes to global warming/climate change / adverse weather;
Note: Do not credit responses that address ozone depletion.
\nlow-lying topography/valley/mountains/high-rise buildings;
low windspeed/air movement;
thermal inversion / hot humid days;
high population density/heavy use of fossil fuels;
cities closer to equator get more intense sunlight;
conversion/reduction of nitrogen oxides/carbon monoxide/hydrocarbons from cars;
\nA surprising number misidentified ozone as a primary pollutant and showed a poor understanding of what is meant by a primary pollutant.
\nA surprising number misidentified ozone as a primary pollutant and showed a poor understanding of what is meant by a primary pollutant.
\nMost were able to link the early rise in nitrogen oxides and hydrocarbons with early use of vehicles and industries burning fossil fuels.
\nA quite significant proportion of candidates simply described the diurnal changes in ozone rather than offering underlying reasons for them.
\nMost were able to identify a clear impact of tropospheric ozone.
\nThe majority were able to recognise high intensity of fossil fuel use as a local condition favouring photochemical smog but a smaller number could additionally identify geographical conditions.
\nThe majority of candidates understood the general role of catalytic converters in reducing smog but few could give their detailed role in removing nitrogen oxides.
\nOutline, using examples, the differences between primary and secondary pollution.
\nExplain the causes and effects of acid deposition on natural ecosystems.
\nTo what extent is pollution impacting human food production systems?
\nPrimary pollution:
is active upon emission of pollutant;
eg carbon dioxide/sulphur oxides/ozone/lead/nitrates/phosphates/heat/light;
Secondary pollution:
occurs when primary pollutants undergo some kind of physical or chemical change;
nitrogen/sulphur oxides combining with water to form nitric acid/sulphur acid/acid rain;
nitrogen oxides/VOCs combining to form tropospheric ozone/photochemical smog;
Note: some pollutants (eg ozone/sulphur oxides) can be credited as both a primary and secondary pollutant but to gain credit for the latter there must be an identification of a primary pollutant from which it is derived.
\nDo not accept eutrophication (eg toxic substances released from algal blooms) as example of secondary pollutant.
\nCauses:
burning of fossil fuels releases NOx/SOx;
the sources of these are mainly coal-burning industries/transportation/electricity generation;
emissions from livestock/use & production of inorganic fertilizers also contribute;
volcanic eruptions can also cause acid rain/release oxides of N/S;
NOx/SOx react with water to form acid deposition;
this acid may be deposited locally as dry deposition or dissolve in air moisture and reach ground by wet precipitation;
nitrous oxides produce nitric acid / sulphur oxides produce sulphuric acid;
wind may carry primary pollutants causing ecological damage to be widespread.
Effects:
direct adverse effect of acidity on living organisms eg kills lichens / plankton / fish / soil microbiota;
causing leaf-fall/thinning of waxy cuticle/reduced immunity to disease/root damage in terrestrial plants;
leading to reduced primary production/plant growth;
indirect toxic effect by changing chemistry of soil/water;
eg increased solubility/leaching of plant nutrients/reduced soil fertility;
eg increased solubility/release of toxic metals/aluminium damaging fish/plants;
such toxic metals might undergo bioconcentration/biomagnification;
overall, may therefore cause loss of biodiversity/reduction in food chains/webs etc.
Note: Do not credit biomagnification except in the explicit context of releasing heavy metals. And do not credit impacts of ocean acidification or impacts on limestone/urban infrastructure which are beyond the limits of this question.
Award [5 max] if either causes or effects are not included in response.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although ‘ESS terminology’ has been conflated with ‘Understanding concepts’). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nOutline the factors that contribute to total biodiversity of an ecosystem.
\nExplain how ecological techniques can be used to study the effects of human activities on the biodiversity of a named ecosystem.
\nTo what extent are strategies to promote the conservation of biodiversity successful?
\nbiodiversity includes the diversity of species, habitat and genes;
species diversity involves both the variety/number of species/richness and their relative proportions/evenness;
habitat diversity refers to the range of different habitats in an ecosystem or biome;
...which may vary due to environmental gradients/changing abiotic conditions/altitude/latitude/major disturbances (volcanic activity/landslides, etc);
habitat/niche diversification promotes species diversity;
genetic diversity refers to the range of genetic material/genes in a population/species;
...which is influenced by mutation/sexual reproduction/natural selection/speciation;
high primary productivity/insolation/precipitation/optimum abiotic conditions promote biodiversity;
succession promotes greater biodiversity by increasing length/branching of food chains / because it leads to improved abiotic conditions.
Credit can be gained through description of particular ecosystems eg. climax communities; hotspots; but the specific factors must be identified to gain credit.
Do not credit human impacts or any factor reducing biodiversity.
\n
named ecosystem, eg shallow stream running through woodland;
\nstudies should be made before and after human activity/in proximal and distal positions from activity;
Explanation: to provide evidence of human causation/correlation;
transects and quadrats may be used to sample area;
Exp: to reduce overall workload but be representative of area;
sampling should be repeated over time/distance;
Exp: to increase reliability;
abundance/biomass of biotic components may be measured;
Exp: to assess whether population size/productivity of populations/species have been affected.
numbers of motile organisms can be measured using Lincoln Index/mark–release–recapture;
Exp: because quadrats are ineffective if organisms are constantly on the move;
abiotic components may be measured using probes/thermometers/chemical tests, etc;
Exp: because human activity may alter prevailing abiotic conditions;
indicator species may be identified/quantified (using keys);
Exp: because their presence/abundance will indicate degree of human impact;
species diversity can be measured using a diversity index (eg Simpson’s);
Exp: because the index takes into account both species richness and equitability/distribution/relative abundance / can quantitatively compare different habitats/same habitat over time;
genetic & habitat diversity can be identified;
Exp: because these are also components of overall biodiversity.
Award [6 max] if no named ecosystem.
Award [4 max] if no explanations for use of techniques are given
There should be no credit given for extra detail of methods/techniques or for potential results of those methods. Focus of question is on purpose of techniques.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although ‘ESS terminology’ has been conflated with ‘Understanding concepts’). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nFigure 2: Projected global water scarcity 1995–2025
\n[Source: With permission from GRID-Arendal. Source adapted.]
\nState the general pattern of change in global water scarcity predicted from 1995 to 2025 as shown in Figure 2.
\nIdentify two ways in which climate change may influence the predicted change shown in Figure 2.
\nIdentify two possible human influences, not related to climate change, that may cause the changes in water scarcity predicted for 2025.
\nOutline two reasons why some countries are unlikely to experience water scarcity.
\nin many countries water scarcity will increase / higher percentages of water present will be extracted;
changes are usually greater in the mid to lower latitudes/nearer the equator (than the poles);
increased global temperatures will change wind/precipitation patterns affecting water supplies;
increased precipitation will increase availability reducing scarcity / decreased precipitation will decrease availability increasing scarcity;
increased temperatures will increase evaporation losses/drought/drying up of water sources (lakes, rivers, reservoirs) reducing availability;
increased temperatures will melt ice storages increasing availability / run off into oceans decreasing availability;
rising sea levels may cause salinisation of freshwater sources;
increased population (demanding more water);
increased/intensive food production/agriculture (demanding more water);
increased standards of living/industrialization (demanding more water);
increased levels of contamination/pollution (through industrial development);
damming of river/water supply upstream reducing available water downstream;
increased surface run off due to urbanisation;
favourable climate where precipitation is high/evaporation is low;
countries may have large replenishable storages (e.g. lakes/rivers/ice);
developed countries with technology for effective water harvesting / desalination;
more ecocentric value systems promoting sustainable use of water resources / limited pollution;
no external conflicts over water sources;
low population densities (with lower industrial/agricultural/domestic demands);
low standards of living (with lower industrial/agricultural/domestic demands);
Most were able to identify the general pattern of increased scarcity although some got tied up in specific details of individual countries.
\nMost identified either positive of negative impacts of climate change on water scarcity.
\nMost were able to suggest at least one human influence on water scarcity other than through climate change.
\nMost could explain at least one reason why some countries did not experience water scarcity.
\nOutline how species diversity and population size influence the resilience of an ecosystem.
\nDescribe the similarities and differences in using a biotic index and a diversity index to assess ecosystems.
\nWith reference to named examples, discuss the significance of diversity in the sustainability of food production systems.
\ngreater species diversity/greater population size usually lead to greater resilience;
with more species, it is more likely others can take over the role/niche of any lost/declining species;
more food chains/energy/biogeochemical pathways in an ecosystem provides redundancy therefore greater stability;
a variety of species is more likely to include those resistant to environmental change;
larger populations provide greater storages that can last over periods of lower productivity; larger populations generally carry greater genetic diversity;
larger populations of invasive species may lead to reduced diversity/resilience;
lower populations are more prone to extinction after a disturbance (e.g. habitat fragmentation) / or due to stochastic fluctuations;
an ecosystem may be more resilient if there are many small populations of different species than one large population of a single dominating species;
large populations of foundation/keystone species may be crucial for resilience of certain ecosystems (e.g. corals, kelp, beavers, elephants, pines, hemlock);
Note: Award credit to any valid arguments providing they directly relate species diversity or population size to resilience.
Award [3] max for responses addressing only diversity or only population size.
Similarities:
both may involve species identification;
both may involve quantitative sampling/estimating the abundance of living organisms;
both require multiple samples for effective comparisons/reliability;
both indices involve evaluating the range/variety of different species;
both involve calculating a single figure (index) from a collection of data;
Differences:
only biotic indices (not diversity indices) give different values to sensitive and tolerant species;
biotic indices are specifically used for evaluating impact of pollution whereas diversity indices just measure variety and evenness of species/general condition/maturity of an ecosystem;
diversity indices are appropriate for most ecosystems whereas biotic indices are usually for aquatic systems;
biotic indices usually focus on animal species/macroinvertebrates alone whereas diversity indices can be used for plant or animal communities;
diversity indices usually address all species present in system whereas biotic index focuses on a particular selection;
Note: Award [4] max if only similarities or only differences are given.
Only credit differences where both sides of the contrast are given or clearly implicit. No credit for naming indices eg Simpson’s, Trent etc.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMost candidates had some idea regarding the influence of species diversity and population density on resilience but few were able to gain the full credit available.
\nAlthough the majority of candidates had some idea of a 'diversity index', few had sufficient understanding of a 'biotic index' to effectively compare and contrast them.
\nThis was generally well-answered with many relevant examples of terrestrial and aquatic food production systems and particularly the distinction between examples of polyculture v monoculture.
\nOutline how energy drives the hydrological cycle.
\nExplain, with the use of a system diagram, how human activities affect flows in the global water cycle.
\nTo what extent do the approaches and strategies of different environmental value systems improve access to fresh water?
\nprimary source of energy driving hydrological cycle is solar energy;
solar energy causes changes of state in water eg evaporation/sublimation/melting/transpiration;
condensation of water releases (latent) heat energy causing air to rise/hurricanes;
solar energy causes the temperature differences that create winds/cause movement of water vapour in the atmosphere/advection;
kinetic/wind energy moves clouds (from ocean over land, usually);
solar energy melts ice producing streams/lakes/rising ocean levels;
solar energy causes both transfers (eg advection) and transformations (eg evaporation) in hydrological cycle;
precipitation/run-off/streamflow occurs due to gravitational energy/difference in potential energy between the high and low positions;
transpiration is driven by opening of leaf stomata which is due to chemical energy (cellular respiration in mitochondria).
Award up to [4 max] for identifying following impacts either on the diagram or in words:
\nmelting (1) will increase due to global warming/climate change/increased greenhouse gas emissions;
freezing (2) will decrease due to global warming/climate change/etc;
precipitation (4,6,8) will be polluted due to acid formation/emissions of NOx & SOx/ combustion of coal;
precipitation (4,6,8) could change/increase/decrease due to climate change/etc;
percolation/infiltration (8) will decrease due to urbanisation / soil compaction caused by eg overgrazing;
run-off (5) will increase due to urbanization/deforestation;
warmer/polluted streams (5) due to thermal/toxic pollution from industrial effluent;
evaporation (3,7,9) will increase due to global warming/climate change/etc;
evapotranspiration (10) will increase due to global warming/climate change/etc;
evapotranspiration (10) will be reduced due to deforestation;
uptake by plants (11) will be reduced due to deforestation / urbanization / long fallow periods;
groundwater flow/aquifers (12) will change dependent on climatic impacts/precipitation / rate of human extraction;
cloud seeding increases precipitation (4,6,8) (addressing problem of drought/fog around airports).
Award up to a further [3 max] for quality of diagram, giving 1 mark for every 3 correctly labelled flows or storages. No marks for less than 3.
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although ‘ESS terminology’ has been conflated with ‘Understanding concepts’). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nFigure 3: Mean ozone hole area between 1979 and 2016
\n[Source: NASA Ozone Watch.]
\nState where the ozone hole referred to in Figure 3 is located.
\nDescribe the changes in mean ozone hole area between 1979 and 2016.
\nIdentify one possible reason for the changes shown during the 1980s.
\nExplain how the data in Figure 3 can be used in judging the success of the Montreal Protocol in addressing ozone depletion.
\nin the (lower) stratosphere / over the poles / above the Antarctic/Arctic / at higher latitudes / Australia/NZ;
\nrapid increase during the 1980s/up to 1990s/ from 1979–87;
reaches maximum in late 1990s; relative stable during late1990s;
fluctuating from 2000 onwards;
possibly declining in late 2000s/from 2014;
Be prepared to give a little leeway in precise years for changes in trends, but some reference to their timing is required.
\nincreasing use of/disposal of refrigerants containing CFCs;
increasing use of CFCs in aerosols;
increasing release of NOx from fossil fuel combustion; increasing use of methyl bromides as pesticides;
Responses should identify the ODS and its use for full credit.
\nMontreal Protocol was introduced in 1987/graph covers period before and after introduction of Montreal Protocol;
it introduced a ban on the use of CFCs / led to use of alternative HCFs/HFs;
rate of ozone destruction/growth of the ozone hole slows down/stops soon after this date;
suggesting it had some success/favourable impact on ozone depletion;
however, there is little evidence of ozone levels being restored to earlier levels / hole disappearing;
possibly some evidence in last few years/2014–2016 on graph of ozone hole reducing/ozone being restored;
the stabilisation/limited decline in ozone hole may suggest black market sale of ODSs (limited success);
continued impact of long-lasting ODSs (CFCs/HCFs) delay final judgement;
Most were able to identify either the geographic or atmospheric location of the ozone hole.
\nMany struggled to describe general trends of change in the data of this graph, either opting for just an 'overall increase' or describing year by year changes.
\nFew accurately identified the possible causes of this change in the ozone hole.
\nMany were able to gain some credit for their responses to this question, but few recognised the reduction in RATE of increase in the ozone hole which was the major achievement of the Montreal Protocol and the persistence of CFCs preventing any substantial decline.
\nOutline how the concept of sustainability can be applied to managing natural capital.
\nExplain how environmental indicators are used to assess sustainability.
\nTo what extent does sustainability play a role in making decisions about energy and climate change policies at national and international levels?
\nnatural capital refers to natural resources that can supply a natural income of goods or services;
natural income is the yield/growth obtained from natural resources/capital;
to be sustainable, natural capital must be used at rate slower than its replenishment / within maximum sustainable yield / that fulfils current needs without compromising future availability;
if more than the natural income is extracted, then the use is unsustainable;
exploitation of natural capital may also be unsustainable due to processes of extraction/transport/processing / environment should be in same condition as at outset to be sustainable;
altering human behaviour/values/choices through policies/legislations/campaigns so that unsustainable exploitation of natural capital is reduced;
non-renewable natural capital is either irreplaceable or can only be replaced over geological timescales / non-renewable natural capital can never be used sustainably.
The question addresses the essential nature (concept) of sustainability rather than specific practices. However, do credit candidates for valid and specific examples if they exemplify any of the generic principles above.
\nenvironmental indicators (EIs) may involve measures of biodiversity/
pollution/population/climate/emissions/resource consumption;
EIs are tools for measuring progress toward sustainability/supporting policy evaluation/informing the public/comparing nations;
EIs involve the setting of measurable goals from established baseline measurements;
EIs can be used at a range of scales from local to global;
after some time, measures can be reassessed and compared to the baselines/domestic objectives/international agreements (eg Kyoto/Montreal Protocol);
environmental impact assessments (EIAs) are EIs that measure a wide profile of indicators usually before and after some development;
ecological footprints(EFs) are EIs that focus on rates of consumption compared to rates of natural income;
if a population’s EF is greater than the area available this indicates unsustainability;
the Millennium Ecosystem Assessment used indicators to give a scientific appraisal of the condition/trends in the world’s ecosystems and services;
certain species can be used as indicators of pollution;
some indicator species are particularly sensitive to pollution so a low abundance may suggest heavy pollution / high abundance suggest clean environment (eg lichens);
loss of these sensitive species may be an effective indicator for appealing to the public;
some indicator species are particularly resistant to pollution so a high abundance/dominance of these species may suggest high pollution (eg tubifex worms/coliform bacteria).
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although ‘ESS terminology’ has been conflated with ‘Understanding concepts’). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nOutline the role of the atmospheric system in the distribution of biomes.
\nExplain how human impacts on the atmosphere may influence the productivity of terrestrial biomes.
\nTo what extent is the need for conservation more significant in tropical biomes?
\natmospheric/tri-cellular circulation (including Hadley, Ferrel & polar cells) creates patterns of climate that determine dominant vegetation types;
low pressure due to intense heating/high insolation at the equator causes / rising moist air in the tropics creates high precipitation giving rise to rainforests;
moving polewards (at high altitude), air cools, becomes denser and sinks forming a high-pressure zone / descending/dry air (20–30° latitude/tropics) creates water-limiting/arid conditions giving rise to deserts;
some of the air continues towards the poles to equalize temperature difference / atmosphere transfers heat from (sub-)tropics to mid-latitudes giving rise to temperate biomes;
descending/dry air (high latitude/polar regions) creates water-limiting conditions in tundra;
water vapour (from mid-latitudes/temperate regions) is transferred to high latitudes giving rise to heavy precipitation/snow in boreal forest;
water vapour is transferred from ocean surfaces overland generating freshwater aquatic systems;
prevailing winds/jet streams (blowing from high to low pressure) bring precipitation to a region, e.g. temperate rainforest in mountainous region/riverine/water-margin systems;
rain shadow effect of high mountains causes dry winds in the leeward side, resulting in arid or semi-arid biomes (e.g. Tibetan Plateau, Mongolian Gobi desert and steppes);
atmosphere may be responsible for shifting biomes due to global warming/climate change;
release of ozone-depleting substances reduces stratospheric ozone increasing UV on Earth...;
UV can damage plants/photosynthesis reducing primary productivity;
release of NOx/SOx from fossil fuels can generate acid precipitation...;
acid rain can damage plants/leaves reducing primary productivity;
acid rain can cause leaching of nutrients from soils reducing plant growth/productivity;
acid rain can release toxic cations/minerals in soil that reduce plant growth/productivity; emission of greenhouse gases can lead to an increase in global temperatures/global warming...;
increased temperatures may lead to higher rates of photosynthesis/increased productivity;
higher temperatures may damage certain plant species reducing productivity;
higher temperatures may cause greater evaporation/water scarcity that reduces plant growth/productivity;
higher temperatures may melt permafrost increasing primary productivity in tundra / ice retreat, e.g. in Greenland, can lead to expansion of tundra ecosystem;
emissions from fossil fuel combustion causing photochemical smog which reduces photosynthesis;
any reduction in primary productivity will lead to reduction in secondary productivity/productivity of consumers;
Note: Credit may be given for any further potential impacts of atmospheric pollution on productivity of terrestrial biomes.
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nWhile many had some idea of the tri-cellular model of atmospheric circulation they were often unable to link this closely with the distribution of biomes.
\nIt was this question that revealed the perennial confusion over climatic pollution issues with many candidates identifying UV radiation as the cause of global warming and greenhouse gases as the cause of ozone depletion and many similar mistaken associations.
\nThis question generated many very good responses identifying the many values of tropical biomes and the associated issues of their conservation. Only the better responses, however, considered some counterarguments in favour of other biomes.
Outline the processes by which a species may evolve a greater tolerance to higher temperatures.
\nExplain how the atmosphere plays a role in maintaining life-supporting temperatures over the Earth’s surface.
\nIn addressing environmental issues, mitigation strategies may be seen as primarily ecocentric and adaptation strategies as primarily technocentric.
\nTo what extent is this view valid in the context of named strategies for addressing the issue of global warming?
\na species will contain a variety of different genotypes/characteristics / mutations will increase the variety of genes/characteristics;
some genes may provide greater tolerance to high temperature than others;
individuals with these genes are more likely to survive if high temperatures are limiting / there will be “survival of the fittest” / tolerant will outcompete intolerant;
these individuals will reproduce offspring with their tolerance/genetic characteristics / their characteristics are heritable/passed on to next generation;
natural selection will eliminate intolerant individuals/increase frequency of tolerant individuals;
over time/generations, tolerance may become a dominant characteristic in population;
If candidates mistakenly address process of speciation then just credit those aspects that are equally valid in microevolution, e.g. natural selection/survival of fittest/heritability, etc.
\natmosphere allows solar energy/wide range of wavelengths to reach Earth’s surface;
water vapour/humidity/clouds absorb/reflect incoming IR/solar energy exerting a cooling effect;
greenhouse gases such as CO2/methane/NOx/tropospheric ozone/ CFC/HCFCs/water vapour;
absorb re-radiated heat/outgoing longer wavelength (Earth's) radiation;
this creates greenhouse effect that keeps planet warmer;
most heat is radiated to the equatorial/lower/tropical latitudes;
the tricellular model/convection currents/prevailing winds transfer this heat to higher latitudes;
maintaining a greater dispersal of life-supporting temperatures over planet;
heat at equator causes rapid evaporation;
…this water vapour carries latent heat that can be released on condensation/at higher latitudes;
tropical cyclones transfer large quantities of such heat to higher latitudes;
winds may contribute to oceanic currents transferring heat;
Credit should be awarded only for MPs that address role of atmosphere, not other influences on temperature.
Do not credit response that ozone hole leads to warming...unless it is qualified by being a relatively insignificant contribution.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMany candidates were able to describe processes of natural selection and survival of the fittest, although some confused their response with references to speciation.
\nFew candidates scored well on this question primarily through confusing the role of the ozone layer with global warming. From a large sample of scripts, over 60 % of candidates were under the mistaken impression that 'the prime cause of global warming was the hole in the ozone layer that has been damaged by greenhouse gases like CO2 and methane'! It is phenomenal how popular this mistaken myth predominates amongst the candidature. It was a minority that were able to think beyond the greenhouse effect and address reflection from clouds, convections cells and tropical cyclones spreading heat and latent heat over the Earth's surface.
\nGenerally, there were many good responses to this question. However, there was a tendency for error to creep in to the clear distinction between mitigation and adaptation. Strategies like carbon capture, renewable energies, afforestation were commonly and mistakenly addressed as adaptation strategies. The fact that adaptation strategies are those enabling us to live with the impacts of climate change rather than attempting to reverse them, was not clearly grasped by many candidates.
\nFigure 1(c): Ecosystems of Dominica
\n[Source: © International Baccalaureate Organization 2020.]
\n\n
[Source: The Dominica Story: A History of the Island. Lennox Honeychurch ©1995 Macmillan Education.
Reproduced with permission of the Licensor through PLSclear.]
Figure 1(d): Climate graph for Roseau, Dominica
\n[Source: Adapted from World Weather & Climate Information, Climate and Average Monthly Weather in Roseau, Dominica.
Available at https://weather-and-climate.com/average-monthly-Rainfall-Temperature-Sunshine,roseau,Dominica.]
Using Figure 1(c), state one ecosystem found at sea level in Dominica.
\nWith reference to Figure 1(d), explain how the environmental conditions on Dominica result in high gross primary productivity.
\ndry scrub woodland / littoral woodland / seasonal forest;
\n2000–2500 mm precipitation per year / over 100 mm/high precipitation in every month of the year / high rainfall throughout the year;
…means that water supply is not limiting, allowing for rapid plant growth; warm temperatures consistent all year / mean temperature ranges from 25–28 °C all year;
…contribute to plant growth throughout the year / high rate of photosynthesis
…allows for rapid decomposition of organic matter and rapid nutrient cycling;
Note: Award [1] for the environmental condition, and [1] for relating this to high GPP.
Do not accept “fertile soil” or “tricellular model”.
Do not accept ‘high precipitation/warm temperatures’ without recognition it occurs throughout the year.
The majority of candidates correctly answered this question. However, a number of candidates did not appear to understand the concept of 'sea level'. Incorrect responses included coral reefs, rainforest or naming one of the national parks.
\nMost responses lacked the necessary detail required to achieve full marks. Candidates frequently did not indicate that high precipitation or warm temperatures occurred throughout the year which allowed for a high rate of photosynthesis resulting in high gross primary productivity.
\nOutline four ways in which urbanization may influence processes in the hydrological cycle.
\nHydropower is a resource that can be exploited from rivers. Explain how the value of this resource to a society may vary over time.
\nTo what extent are water scarcity issues better addressed through changing human behaviour than through technological development?
\nurban (paved) surfaces/reduced veg cover will lead to increase in run-off;
…and thus increase stream-flow/flooding;
urban (paved) surfaces/reduced veg cover will reduce infiltration of water into soils;
…and thus reduce inputs to groundwater/aquifers/water table level;
urbanization can increase heat/local temperature leading to greater evaporation/downwind precipitation;
urbanization will reduce vegetation cover and thus reduce evapotranspiration/regional precipitation;
urbanization will increase local water extraction reducing river flows/increasing outputs from groundwater storages/aquifers;
urbanization may lead to increased emission of greenhouse gases/global warming /climate change that may result in multitude of changes in hydrological cycle e.g. increased melting of glaciers/shifting precipitation patterns/increased evaporation etc.;
urbanization may lead to increased emissions of NOx/SOx leading to acid precipitation;
Note: Ensure that each markpoint includes an explicit link to a direct consequence of urbanization and how this influences a process in the hydrological cycle.
Award [1] max for changes associated with global warming.
Positive changes promoting the value of hydropower:
rise in environmental awareness/need for renewable energy may increase value of hydropower;
need for industrial development entails increased demand for energy, thus increasing value of hydropower;
improved/more efficient technology of dam building making the political decision more attractive to voters / increasing the margin of profit / reducing the initial investment for LEDCs / making overall project more sustainable;
technological development of small scale/damless projects may render hydropower more aesthetically appealing / cheaper to implement in LEDCs / more environmental-friendly / more fit to ecocentrists;
hydropower may become favoured due to depletion in local non-renewable sources/need for energy security;
Negative changes reducing value of hydropower:
impacts of hydropower on aquatic systems / local human settlements cause increasing conflict with cultural values/local needs;
other renewable resources may become more favourable through technological development/reduced costs;
decreasing rainfall/increased evaporation due to climate change renders an existing dam less efficient / profitable;
energy security reasons / political change / economic recession dictate shift from hydropower to more dense nuclear power / cheaper coal;
societal values/EVS may stop seeing damming of a river as sustainable and demand shift away from river dams to wind/solar power;
society realizing it was unethical to relocate a local tribe and demanding the restoration of the river;
Note: Do not credit general arguments on dynamic nature of natural capital, unless explicitly linked to hydropower or clearly discussed in the context of hydropower.
Do not credit any argument relating to the high value (monetary, intrinsic, aesthetic, environmental, cultural, economic, ethical, social, spiritual, technological) of hydropower, if not explicitly shown how this value has changed over time. (e.g. local Native American tribe resents river diversion due to its spiritual value; this is not a valid MP, as no change shown, just a different value system).
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials Positive changes.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nThe majority of candidates seemed to approach this question with confidence but were often too generalised and failed to specifically identify impacts on 'processes' of the water cycle like percolation, infiltration, run-off, transpiration etc.
\nThe majority of candidates could identify two or three causes of a change in the dynamic value of hydropower but few extended their imagination to gain full credit for this question.
\nThere was a tendency in addressing this question for candidates to prioritise small scale water saving strategies around personal ablutions and laundry rather than more extensive behaviours like those associated with global warming, population growth or food production. While there was generally some understanding of technological strategies like desalination and drip-irrigation these were often assessed as less significant than turning the tap off while cleaning teeth.
\nOutline the procedures in a laboratory-based method to find the gross productivity for a population of named aquatic animals in terms of biomass per day.
\nExplain how acid deposition falling on a forest may impact a nearby aquatic ecosystem.
\nWhen harvesting is limited to the sustainable yield, associated processes involved in a food production system may still make the production unsustainable.
\nIn this context, to what extent can aquatic food production systems be truly sustainable?
\nfind the dry weight of food presented to the population at start;
collect and find the dry weight of food remaining after a number of days;
subtract the weight of food remaining from that presented / find dry weight of food eaten;
collect and find the dry weight of feces produced over this period;
subtract weight of feces from food eaten to find food absorbed/gross productivity / food eaten − fecal loss = gross productivity;
divide final weight/gross productivity by number of days of the study;
Do not credit reference to weighing organisms (only relevant in net productivity).
\nrun-off/groundwater flow may carry acidity directly to water body;
acidity/low pH may directly reduce survival of sensitive species;
reduced productivity of aquatic plants reduces food for higher trophic levels;
acidity in soils will release/leach cations/metal ions from soil particles;
aluminium/metal ions released from soil will enter water body;
aluminium ions may affect gills of fish reducing their survival;
other metal ions (cadmium) may be more toxic/lethal;
acidity reduces solubility of nutrients (e.g. N, P) so less nutrients leach/flow into aquatic system;
loss of trees/terrestrial/riparian vegetation may lead to erosion of soil into water body/reduced shade/increased temperatures;
more soil entering water body will increase turbidity;
high turbidity may lead to reduced photosynthesis/lower productivity;
all these impacts will lead to loss of biodiversity/low productivity;
forest soil may be alkaline reducing acidity of impact on aquatic system;
Only credit impacts on aquatic system, not impacts solely affecting forest.
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nThe majority of candidates scored little, if anything, for this question as they confused gross with net secondary productivity and hence described strategies of finding dry weight of organisms that was unnecessary. Those that recognised the concept as being 'dry weight of food absorbed' found it easy to identify a method by subtracting dry weight of faecal loss from that of food eaten.
\nMany candidates scored some credit here, identifying the run-off into water bodies damaging plants and animals and leading to loss of biodiversity. Few considered more widespread impacts of soil erosion, release of aluminium, impact on nutrients, etc.
\nMany candidates could identify some ways in which the process of harvesting or farming of fish could be unsustainable even with application of maximum sustainable yield. There were also several very thorough responses to this question which considered multiple factors.
\nFigure 2(a): Fact file about the red-necked and imperial amazon parrots
\n[Source: © International Baccalaureate Organization 2020.]
\nFigure 2(b): Changes in the numbers of individual imperial and red-necked amazon parrots
\n[Source: Paul R. Reillo, Ph.D., President, Rare Species Conservatory Foundation, Director, Tropical Conservation Institute,
Research Professor, Institute of the Environment, Florida International University.
Data from World Parrot Trust, 2019. https://www.parrots.org/projects/red-necked-amazon.
\nACTP. ACTP responds to the commentary concerning conservation measures required for the endangered
Amazon parrots of the Commonwealth of Dominica. 2018 Available at:
https://www.act-parrots.org/wp-content/uploads/2018/04/Dominica-Statement.pdf.]
Using Figure 2(a), state one physical characteristic that may be used to differentiate these two species from each other in an identification key.
\nWith reference to Figure 2(a), state the type of biotic interaction that occurs between the imperial amazon and the red-necked amazon parrots.
\nCompare and contrast the realized niches of the two parrot species.
\nWith reference to Figure 2(b), calculate the percent increase in red-necked amazon numbers between 1980 and 2012.
\nWith reference to Figures 2(a) and 2(b), suggest two reasons why the red-necked amazon population has recovered more quickly than the imperial amazon population following Hurricane David in 1979.
\nchest/underbelly colour (green v. grey/blue);
head colour;
neck/throat marking (red v. grey/blue);
beak colour;
foot colour;
Note: Do not accept only ‘colour is different'.
\ncompetition / inter-specific competition;
competition for nesting sites/food (where their distributions/habitats overlap ie altitudes 600–800 m);
resource partitioning;
both species nest in holes in trees;
both species eat fruit and nuts;
the imperial amazon feeds only in dense forest, whereas the red-necked amazon feeds in forests and plantations/red-necked amazon also eats in banana and citrus plantations;
the red-necked amazon lives between 0 and 800 m, whereas the imperial amazon lives between 600 and 1300 m/at higher elevations / both live between600 and 800 m;
Note: Must be evidence of comparison in the response: at least one compare and one contrast statement for full marks.
\n;
\nNote: Accept between 635 and 681. Accept values with decimals.
\nRed necked amazon (RNA) more social so protection in numbers from predators, reducing mortality rates/increasing survival rates / imperial amazon (IA) lives singly so at greater risk of predation;
RNA more social so greater breeding success/greater choice of potential mates / IA has reduced mating success due to solitary behaviour/may not breed again after the loss of a mate during the hurricane / IA may die if it loses its partner;
RNA eat fruit from banana and citrus orchards/wider variety of food sources, so less competition for food / IA has a more limited food source so has greater competition for food;
RNA less specialized/can adapt to a number of different habitats so less affected by hurricane damage to the forest;
IA being outcompeted for nesting sites by the RNA;
time taken for rainforest to recover after hurricane means delay in recovery of IA / humans replant orchards so food source for RNA recovers more quickly;
initial population of RNA was higher in 1980;
This question was answered well by the majority of candidates. A few responses were too vague for credit, for example stating the birds differed in colour without reference to specific parts of the bird.
\nMany candidates correctly stated the interaction between the two types of parrots. However, a significant number of responses described feeding and nesting habits of the birds without stating the actual biotic interaction that was necessary for credit.
\nThis question was well answered by many candidates. A common error was not to cover 3 different aspects for the 3 marks. For example, some candidates focused only on the altitude the birds inhabited.
\nFew candidates correctly calculated the percent increase.
\nOverall this question was well answered. Common error was to only focus on one reason rather than two.
\nOutline the processes involved in the formation of fertile soils from bare rock.
\nExplain how negative and positive feedback mechanisms may influence the growth of decomposer populations in the soil.
\nTo what extent are natural limiting factors more likely than population policies to limit global human population growth in the future?
\n(mechanical/chemical) weathering/breaking up of parent rock producing small particles;
deposition of sediment/eroded material (through wind/water) increasing soil depth;
dissolving of particle material to release soluble minerals;
colonization of parental rock/sediments by plants/animals/decomposers/pioneer species;
biological/atmospheric nitrogen fixation adds available nitrogen (nitrates, ammonium) to soil;
activity of mycorrhizal fungi/decomposition of dead organisms/leaf litter to release mineral/nutrients/organic material/humus;
growth of mosses form mats that stabilize soils in sterile/barren ecosystems;
earthworms/burrowing insects spread soil particles/open soil pores;
precipitation adding water to soil;
negative feedback occurs when the output of a process inhibits or reverses the same process / in such a way as to reduce change/counteract deviation/maintain equilibrium;
\npositive feedback occurs when the output of a process accelerates that same process (will tend to amplify changes) / deviate away from equilibrium / or drive the system toward a tipping point (adopting a new equilibrium);
\nNegative feedback (occurring at carrying capacity):
growth of decomposer populations will reduce available organic material;
…thus leading to reduced growth in population;
growth of decomposer population may lead to increase in predators feeding on decomposers;
…thus leading to reduction in population growth;
Positive feedback (occurring during phase of exponential growth):
increase in number of decomposers will increase potential for reproduction;
…thus leading to increased rate of population growth;
increase in decomposers may favourably modify environment (e.g. increase temperature/improve soil);
…thus leading to increased rate of population growth;
Note: Candidates may answer with the help of a diagram (e.g. feedback-links diagram) for which credit should be given.
Award [2] max for each valid feedback loop correctly identified.
Only give credit if a complete loop is identified i.e. an increase of factor X leading eventually to a decrease or further increase of factor X (or the converse).
Do not credit simple changes in decomposer populations.
Refer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMost were able to identify key processes in the formation of fertile soil apparently from their understanding of early succession which was quite appropriate.
\nAlthough candidates appeared to grasp the principles of negative and positive feedback they generally couldn't fine the imagination and fresh application to identify examples in the context of decomposers.
\nThis question was often answered very well including references to many potentially limiting factors, Malthusian principles, Boserup's counterarguments, population policies and their limitations.
\nWith reference to four different properties of a soil, outline how each can contribute to high primary productivity.
\nExplain how the level of primary productivity of different biomes influences their resilience.
\nDiscuss the role of feedback mechanisms in maintaining the stability and promoting the restoration of plant communities threatened by human impacts.
\nparticle size affects ability of soil to store/retain water necessary for productivity;
high mineral content provides nutrients for healthy growth/productivity;
high organic content / deep humus provides long term storage of nutrients (released through decomposition);
air spaces provide more O2 to roots for growth/respiration / allow deeper penetration of roots;
appropriate porosity allows soil to hold enough water for plant growth;
better drainage prevents water-logging that inhibits growth/productivity;
abundant biota help to aerate/break up the soil allowing for better root growth/recycle nutrients;
microorganisms contribute to mineral-cycling promoting growth/productivity;
neutral to slightly acidic pH is the optimal for most plants (6.0–7.5);
low or no slope prevents water erosion / loss of soil;
No credit for ground cover reducing wind erosion / soil conservation/management (not soil properties).
\nresilience is the ability to withstand disturbances / tendency to maintain stability/avoid tipping points;
generally, biomes with higher primary productivity (e.g. rainforests/estuaries/wetlands) are more resilient than those with lower productivity (e.g. tundra/deserts);
more productive biomes can support more species/diversity;
diversity increases resilience because loss of one species is more easily replaced by others;
more productive biomes support more branching food chains / greater complexity of interrelationships;
…that allows for more negative feedback mechanisms/shifting feeding habits maintaining stability/providing more resilience;
more productive biomes produce larger biotic storages;
larger storages are less likely to be eliminated/reduced beyond a tipping point so contribute to greater resilience;
larger storages provide higher maximum sustainable yields so are less prone to overharvesting;
higher productivity entails faster plant growth, thus more effective regeneration after a disturbance;
oceanic biomes have low productivity per unit area but their large size increases their resilience;
coral reefs have high productivity but narrow niche requirements give them low resilience;
Allow credit for valid counterexamples as in last two MPs.
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nCandidates generally demonstrated considerable appropriate knowledge in response to this question but often struggled to identify four discreet points.
\nMost were able to link high productivity with high resilience but were often limited in the extent of their explanation.
\nCandidates struggled with this question, mainly due to a limited grasp of the nature of feedback, in particular, how positive feedback mechanisms can be advantageous in the context of regrowth and re-colonisation through succession. Few candidates could clearly apply concepts of negative or positive feedback to the context of plant communities.
\nFigure 4(a): Demographic data for 2018
\n[Source: Data from: CIA, 2019. The World Factbook: Costa Rica. Available at: https://www.cia.gov/library/publications/theworld-
factbook/geos/cs.html/ [Accessed 06 November 2019].]
Figure 4(b): Age–gender pyramid for Costa Rica in 1990 and
projected pyramids for 2020 and 2050
[Source: Population Pyramid. Costa Rica 1990, 2020 and 2050. [online] Available at: https://www.populationpyramid.net/costa-rica/1990/, https://www.populationpyramid.net/costa-rica/2020/, https://www.populationpyramid.net/costa-rica/2050/ Made available under a Creative Commons license CC BY 3.0 IGO: http://creativecommons.org/
licenses/by/3.0/igo/ [Accessed 06 November 2019].]
Based on the 2018 data in Figure 4(a), calculate the doubling time for the population of Costa Rica.
\nWith reference to Figure 4(b), suggest three possible reasons for the changes between the age–gender pyramid for 1990 and that projected for 2050.
\n= 66.67/66.7/67 (years);
\nNote: Accept where there is a dot or dash above the last ‘6’ in 66.6/66.66 as this shows that the ‘6’ is recurring.
Do not accept only ‘66.6’ or other incorrect rounding of the answer.
reduction in births due to greater use of contraception/improved family planning/sex education;
reduction in births due to women having children later/access to education/access to employment/improved status /increase in affluence (more personal choice);
growth in urbanization leading to fewer children required to work in agriculture to support parents / reduction in births because of increasing cost of bringing up children;
reduction in children/births due to improvements in welfare system/pensions reducing reliance on children to support parents;
increase in more elderly population/longer life expectancy/reduction in death rate due to improvement in health care/sanitation;
reduction in infant mortality, so parents can expect most members of a family will survive to adulthood;
reduction in child mortality due to improved nutrition/access to healthcare/immunizations;
government policy/legislation that encourages a reduction in birth rates;
Note: For credit both change observed and associated cause must be given, e.g. do not accept only ‘decrease in birth rate / increase in life expectancy’ or only ‘use of contraception / improved health care’.
Do not accept ‘increase in life expectancy due to better living conditions/better quality of life’.
Do not accept ‘increase in working age people due to migration’.
Do not accept only ‘decrease in birth rates due to education’, for credit needs to also specify either sex education/family planning education or education of women.
A significant number of candidates struggled with this question with some giving no response at all. Common errors included calculating the natural increase rate (NIR) from the data provided instead of doubling time, incorrect rounding of the final answer and incorrect placing of the decimal point.
\nThere were some very good responses to this question. However, common errors included not explaining the reasons for decrease in birth rates or increase in life expectancy or the converse, not explaining the impact of greater availability of contraception or improved health care.
\nFigure 5(c): Development of protected areas in Costa Rica
\n[Source: González-Maya, J.F., Víquez-R, L.R., Belant, J.L. and Ceballos, G, 2015. Effectiveness of Protected Areas for
Representing Species and Populations of Terrestrial Mammals in Costa Rica. PLoS ONE 10(5): e0124480.
doi:10.1371/journal.pone.0124480 [online]. Available at: https://journals.plos.org/plosone/article?id=10.1371/
journal.pone.0124480 This file is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0)
https://creativecommons.org/licenses/by/4.0/ [Accessed 06 November 2019].]
Outline one reason why it is difficult to determine the exact number of species in Costa Rica.
\nExplain three ways in which the development of protected areas shown in Figure 5(c) has improved the conservation of species.
\nshortage of expertise/taxonomy skills to identify species;
shortage of finances to employ experts to classify species;
not all areas have been fully explored / access to remote forest/mountainous areas difficult;
some species are hard to find;
can be difficult to distinguish between some species/sub-species;
Note: Do not accept ‘due to migration/high biodiversity/present in protected areas’
\nprotected areas may prohibit human activities which damage the habitat/threaten species (e.g. urban development/hunting) / protected areas provide a safe place/habitat for species to live;
increase in size/number/coverage of protected areas may lead to:
more habitats protected/covered / more species are conserved;
better support for higher trophic levels/top carnivores;
increased distance from human activities/impacts / reduced edge effects;
more genetic mixing/formation of corridors / increased chance of connecting corridors between the protected areas;
(more people living close to protected areas leading to) greater engagement in conservation efforts / more local communities being involved in conservation / greater community involvement through education/raising awareness/greater familiarity;
more opportunity for ecotourism which encourages continued/further conservation/financial investment into conservation;
more financial support for conservation;
Note: Do not credit ‘increasing habitat size for species could reduce limiting factors’.
\nA number of responses were too vague for credit. Some responses confused determining the number of species present with population size or incorrectly referred to the amount of diversity or number of protected areas in Costa Rica.
\nMost candidates obtained some marks for this question, although few achieved the maximum of 3 marks. Most candidates were able to correctly identify that designation of protected areas could limit human activities which damaged habitats or threated the species living there. However this marking point was frequently repeated within the same response. A few candidates appear to incorrectly view protected areas as a type of zoo.
\nIdentify four ways to ensure reliability of the mark–release–recapture method in estimating population size.
\nExplain how the interactions between a species and its environment give rise to the S-shape of its population growth curve.
\nThe future growth of human populations is unlikely to be limited by the availability of energy resources. However, they could easily be limited by the impacts of energy production.
\nDiscuss the validity of this statement.
\nensure process of capture does not reduce/increase potential for recapture / generate trap-shy/trap-happy individuals;
ensure marking process does not impact individual’s survival;
ensure method of marking is durable for period of investigation;
ensure sufficient proportion of population is caught/marked in first capture;
repeat procedure/recapture to increase reliability;
ensure traps are well distributed throughout area of population;
ensure sufficient time between captures to allow mixing of population;
only apply procedure to motile species that do not travel outside study area;
the slow initial growth rate is due to low numbers reproducing;
…and/or unfamiliarity with resources / threats of the newly colonized habitat;
growth rates/numbers increase more rapidly due to abundance/accessibility of resources/greater numbers reproducing;
…leading to positive feedback/exponential growth;
growth rate subsequently decrease/numbers increase more slowly due to limiting/density dependent environmental factors/environmental resistance;
…e.g. limited food/greater predation/competition/nesting sites, etc.;
growth rate eventually becomes zero / population stabilizes / fluctuates around carrying capacity;
due to reaching the carrying capacity of the environment;
…kept stable by density dependent factors / negative feedback / predator–prey cycles;
Note: These marking points may be achieved through an appropriately annotated diagram.
\nRefer to paper 2 markbands, available under “your tests” tab > supplemental materials.
\nThe following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.
\nAnswers may include:
\nMany candidates gained a mark or two for identifying aspects of reliable mark-release-recapture techniques, but a significant minority seemed unfamiliar with the process.
\nMost candidates had some idea about population growth and interactions with the environment, but a good number mistakenly focused solely upon the population oscillations in the plateau phase rather than the full scope of the S-curve.
\nThere were some excellent responses to this question with candidates well-prepared to take the claim of the question stem to task, with apt and well-explained examples. Weaker essays simply lacked a broad enough scope of such examples.
\nFigure 6(a): Jaguar (Panthera onca)
\nClassified as “near threatened” on the IUCN Red List of Threatened Species
\n[Source: Pixabay.]
\nFigure 6(d): The Barbilla Corridor within the larger international
network connecting jaguar populations
[Source: The Jaguar Project. Costa Rica Wildlife Corridors. [online] Available at: http://www.thejaguarproject.com/jaguar_
corridor_conservation.html [Accessed 06 November 2019]. Source adapted.]
State one criterion used to determine the IUCN Red List status of the jaguar shown in Figure 6(a).
\nDistinguish between the role of the jaguar as a keystone species and as a flagship species.
\nIdentify two difficulties associated with establishing and maintaining wildlife corridors such as those shown in Figure 6(d).
\npopulation size / number of mature individuals;
reduction in population size;
distribution / geographic range / number of locations species is found;
degree of fragmentation;
quality of habitat / loss of habitat / habitat degradation;
probability/risk of extinction;
trophic level;
Note: Do not accept ‘reproduction rates / habitat distribution / degree of specialization / number of species / habitat is under threat’.
\nKeystone species: [1 max]
apex/top predator / integral to the food web/ecosystem;
Flagship species: [1 max]
popular/charismatic image / by protecting it, will help to protect the ecosystems/habitat/other species / used to raise funds for conservation;
Note: Do not accept descriptions of just predators e.g. ‘controls population of primary consumers / eats organisms below it in the food web’.
Do not accept ‘top of food chain / balances the food chain’.
cost of acquiring/managing large areas;
the large areas covered by wildlife corridors can make it difficult to manage;
policing against poaching / greater vulnerability to poaching / corridors are narrow and more affected by edge effect / corridors may pass near or over roads resulting in some roadkill;
displacement of human settlement/industry / may create conflict with people’s use of land e.g. for agriculture;
difficult to determine where to site wildlife corridors / land which is suitable must be available;
challenges of international collaboration;
spread of disease/invasive species from one region to another;
The majority of candidates appear to be familiar with the IUCN Red List criteria and gave an appropriate response.
\nThere were some very good responses to this question, although a significant number of candidates did not attempt this question. A common error was to only describe keystone species as a predator or refer to its role in a food chain rather than in a food web or ecosystem.
\nResponses varied widely for this question. A common error was to give vague responses e.g. corridors are near the capital city without linking this to what specific difficulties this might pose.
\nFigure 3: Climate data for Norilsk and Novosibirsk within the tundra and taiga biome respectively
\nWith reference to Figure 3, suggest two reasons why primary productivity is greater in the taiga than in the tundra.
\nhigher temperatures in taiga which contribute to more plant growth/photosynthesis / lower temperatures in tundra which restrict photosynthesis/plant growth;
more sunlight in taiga contributes to more plant growth/photosynthesis/longer growing season / fewer hours of sunlight in tundra which restricts photosynthesis/plant growth/contributes to shorter growing season in tundra;
Do not accept only ‘more precipitation/higher temperatures/more sunlight in taiga results in greater productivity/biomass’.
Do not accept ‘low temperatures in tundra make it more difficult for plants to survive / plants are adapted to warmer conditions’.
Do not accept more sunlight/rainfall increases nutrients for plant productivity.
Do not accept ‘growth of organisms/species’ instead of ‘growth of plants’.
Overall, this question was poorly answered. Although the majority of candidates identified the factors that enhance primary productivity, the common error was not to link these conditions to levels of photosynthesis or plant growth.
\nFigure 5(b): A family of Chukchi outside their yaranga in Siberia
\nThe Chukchi are indigenous nomadic deer herders who live in yarangas all year round. The yaranga is made from poles of local wood covered in tree bark and animal skins. In winter, a deer skin canopy is added to the yaranga to improve insulation.
\n[Source: SPUTNIK / Alamy Stock Photo.]
\n\n
Figure 5(c): A modern wooden house in an industrial city in Siberia
\nThe house is made mostly from wood, according to local tradition, but with some brickwork and concrete foundations.
\n[Source: EMILIA/Shutterstock.com.]
\nWith reference to Figures 5(b) and 5(c), outline one reason why the yaranga is more sustainable than the modern city house.
\nthe yaranga uses fewer materials/resources/wood to construct than a modern city house;
the yaranga is made of entirely renewable materials, (the city house is not);
all yaranga materials are biodegradable/naturally recyclable, (some city house materials are not);
the city house has associated infrastructure roads/utility supplies etc., the yaranga does not;
production of concrete used in city house produces waste and chemical pollution;
the yaranga is mobile so no permanent destruction of habitat, (city house is not);
yaranga has smaller size;
yaranga is made from local materials, therefore less energy used in transport;
yaranga is made from local materials that are used sustainably;
yaranga may be better insulated/less heat loss;
Do not accept only ‘yaranga has a smaller ecological footprint’.
Do not accept only ‘yaranga made of wood/local/natural materials’.
Do not accept only ‘modern city houses use concrete/bricks/ man-made materials’.
For credit a reason much be given to why the materials used are more/less sustainable.
The majority of candidates gave a correct answer. There was a good variety of acceptable responses. A common error was to state yaranga was made of wood or local materials without explaining why this was more sustainable or that city houses were made of concrete, brick or man-made material without linking this to greater use of energy, production of waste or chemical pollution.
\nFigure 7(a): Variation in forest cover in Costa Rica between 1940 and 2010
\nOutline reasons for the changes in the forested areas over the period shown in Figure 7(a).
\nOutline how the change in the area of forest cover since 1987 may contribute to the mitigation of climate change.
\ninitial decrease/deforestation due to: [1 max]
land clearance for agriculture (growth of cash crops e.g. coffee/sugar/palm oil or for cattle);
logging for timber / demand for wood;
urban development / industrialization;
Note: Do not accept ‘fire caused deforestation / deforestation occurred because areas were not protected / lack of education’.
Do not accept only ‘need for land/resources’.
later increase/reforestation due to: [1 max]
forest was allowed to regenerate naturally;
plantations for timber production;
promotion of tree planting by PES;
ban on deforestation in 1996;
increase in reserve/protected areas;
carbon off-set schemes;
increased environmental awareness on importance of forested areas;
Note: Do not accept only deforestation/reforestation without reasons.
\ntrees/plants absorb carbon dioxide / forest acts as a carbon sink/store;
\nThere were some good responses for this question and many candidates were able to correctly identify a reason that led to deforestation between 1940-1987 and a reason for forestation after 1987. The most common error was to simply state that deforestation occurred without providing a reason for why.
\nMany responses correctly linked the increase in trees to an increase in carbon dioxide absorption or increase in the carbon sink. Although some students incorrectly deduced that there had been a loss of trees/forest in Costa Rica since 1987 which resulted in more carbon dioxide in the atmosphere. In addition, a significant number of students inappropriately focused on trees producing oxygen rather than the importance of trees absorbing carbon dioxide in order to mitigate climate change.
\nFigure 8(c): Conversion to cropland from other land uses in
north-eastern Costa Rica (1986–2011)
[Source: Data from: Fagan, M.E., DeFries, R.S., Sesnie, S.E., Arroyo, J.P., Walker, W. Soto, C., Chazdon, R.L., and
Sanchun, A., 2013. Land cover dynamics following a deforestation ban in northern Costa Rica. Environ. Res. Lett.
[e-journal] (8)034017 http://doi:10.1088/1748-9326/8/3/034017. This file is licensed under the Creative Commons
Attribution 3.0 Unported (CC BY 3.0) https://creativecommons.org/licenses/by/3.0/.]
Explain how the production of cash crops (such as pineapples) may have an environmental impact on soil.
\nExplain how the production of cash crops (such as pineapples) may have an environmental impact on lakes or rivers.
\nWith reference to Figure 8(c), identify where most of the additional land for growing crops came from between 1986 and 2011.
\nintensive agriculture/monoculture results in soil nutrient depletion/reduction in organic matter;
deforestation for plantations leaves the soil bare contributing to soil erosion;
tillage/ploughing can leave soil prone to erosion;
excessive use of pesticides leading to soil toxification;
use of fertilizers increases soil productivity;
use of fertilizers/leaching of nutrients can lead to eutrophication/algal blooms;
use of pesticides can lead to contamination of aquatic systems/death of non-target organisms/bioaccumulation;
over-abstraction of water for agriculture use may lead to low water levels (in rivers/lakes adversely affecting fish/aquatic species);
soil erosion into lakes/rivers could increase sedimentation/reduce water clarity;
Note: For credit the cause and effect needs to be linked.
\n(conversion of) pasture land;
\nResponses were highly variable for this question. A common error was not to link the cause to the effect on the soil or give very generic responses e.g. stating that soil is eroded without an explanation of the cause.
\nMost candidates answered this question well. A popular correct response was to link use of fertilizers to the problem of eutrophication in lakes and rivers.
\nMost candidates correctly identified pasture land.
\nFigure 8(d): Growth in international tourism in Costa Rica (1988–2016)
\nOutline one way in which the trend in tourism shown in Figure 8(d) may affect conservation efforts in Costa Rica.
\nincreased tourism generates more income to invest back into conservation efforts;
biodiversity/wildlife may be considered as an asset to look after to maintain/increase tourism, thereby increasing conservation efforts;
increase in tourism can conflict with conservation efforts by increasing competition for resources / puts greater demand on water resources competing with wildlife / increase demand for infrastructure/hotels/roads/facilities that can destroy habitats;
tourism could adversely affect conservation efforts e.g. disturbing species during the breeding season could reduce successful mating or producing litter that threatens wildlife when consumed;
Note: Do not accept only ‘tourism increases pollution/litter/waste that harms species/ tourism leads to illegal trespassing ’.
\nMany candidates answered this question well with many understanding that some of the income from tourism can be invested into conservation. Some answers lacked the necessary detail for credit e.g. tourism causes pollution that is harmful to species, where neither the specific pollution or the reason it is harmful was given.
\nFigure 9(a): Electricity generation in Costa Rica by energy source (1990–2016)
\nMost of the electricity generated in Costa Rica comes from renewable sources (98.2 % in 2016 and 98.56 % in 2018).
\n[Source: Based on IEA data from IEA (2019) Costa Rica Energy Policy, https://www.iea.org/countries/costa-rica, IEA
(2022), www.iea.org/statistics, All rights reserved; as modified by International Baccalaureate Organization.]
Figure 9(b): Total energy consumption in Costa Rica (including electricity)
between 1990 and 2016
[Source: Based on IEA data from IEA (2019) Costa Rica Energy Policy, https://www.iea.org/countries/costa-rica, IEA
(2022), www.iea.org/statistics, All rights reserved; as modified by International Baccalaureate Organization.]
Figure 9(c): Consumption of crude oil in Costa Rica by sector (2016)
\n\n
[Source: Based on IEA data from IEA (2019) Costa Rica Energy Policy, https://www.iea.org/countries/costa-rica, IEA
(2022), www.iea.org/statistics, All rights reserved; as modified by International Baccalaureate Organization.]
Identify one possible reason why there has been a change in the quantity of electricity generated from wind as shown in Figure 9(a).
\nWith reference to Figure 9(b), calculate the percentage of energy consumed that came from fossil fuels in 2016.
\nWith reference to Figure 9(c), suggest two strategies that would be most effective in reducing the use of crude oil in Costa Rica.
\nimproved/cheaper technology;
change in environmental values / increase in popularity;
greater awareness of benefits of using wind power;
government policy / to achieve country’s goal to become carbon neutral;
increasing demand due to growing population
Note: Do not accept ‘wind power is renewable/unlimited/more sustainable/a green energy source/more viable over the long term/produces less pollution’.
Do not accept 'changes in wind current’.
Do not accept only ‘greater investment/funds available for wind power/renewables’.
Workings: [1 max]
total energy sources: 2399 + 584 + 15 + 826 + 84 (ktoe) = / 3908 (ktoe);
amount from fossil fuels: 2399 + 15 + 84 (ktoe) = / 2498 (ktoe);
% from fossil fuels = 2498/3908 × 100;
Final answer: [1 max]
(=) 63.92/63.9/64 (%);
greater use of public transport that reduces individual car use (and therefore overall use of oil);
use of electric/biofuel/hybrid/hydrogen vehicles/cars (instead of oil-fuelled vehicles) /subsidize electric vehicles / higher tax on petrol cars;
adopting car sharing/pooling that reduces individual use of cars/vehicles;
use of congestion charges;
adopting policy that limits the number of cars a family/household can have;
reducing use of oil-fuelled vehicles by promoting walking/use of bicycles;
use more efficient forms of transport for goods eg boats rather than planes;
promotion of ‘km0 initiative’ (local production and consumption) which reduces need for transportation;
use of carbon tax on oil/petrol (to deter its use) / capping/regulating amount of oil sold;
use of quotas/permits within industry to reduce overall oil consumption;
residents/industry/ agriculture encouraged to use renewable/solar/wind energy (to replace use of oil) / government incentives/subsidizes to use renewable sources of energy;
use energy efficient machinery that requires less oil;
encourage more on-line/home working so people can stay at home (reducing need for travel);
Note: Do not accept ‘build new roads / subsidize green/clean energy / use legislation’.
Do not accept only ‘implement laws / reduce transport / find alternative energy sources / taxes / limit air travel’.
Accept other reasonable responses.
Responses varied widely for this question. A common error was suggesting that wind currents had changed or suggesting there was more investment in wind power without giving a reason for this.
\nMany candidates achieved at least one mark for partially workings. Most candidates correctly calculated the total sources of energy but incorrectly calculated the amount of energy from fossil fuels often omitting oil and coal.
\nMost candidates obtained some marks for this question. Common errors included giving generalised responses e.g. switch to alternative energy sources or not linking the use of public transport, car-pooling or bikes to a reduction in individual car use.
\nFigure 10(b): Ecological footprint and biocapacity per person
in Costa Rica (1961–2016)
Biocapacity is the amount of biologically productive land, measured in hectares per person.
\n\n
Global Footprint Network. Costa Rica (2022) [online] Available at: http://data.footprintnetwork.org/#/. Source adapted.
\nWith reference to Figure 10(b), explain how sustainability in Costa Rica changed between 1961 and 2016.
\nEF must be lower than biocapacity to be sustainable / if EF is above biocapacity, it is not sustainable / overall sustainability declined overtime as EF increased and biocapacity declined;
until around 1990/1991 Costa Rica was sustainable as EF was lower than the biocapacity;
after 1990/1991, EF was greater than biocapacity and therefore Costa Rica was less/no longer sustainable;
Note: For credit, link must be made to change in sustainability.
\nA significant number of candidates struggled with this question. Many were able to correctly link the changes in ecological footprint (EF) and biocapacity to sustainability. A common error was to describe the trends in EF and biocapacity but not link this to sustainability. Only a small proportion of students were able to correctly explain why Costa Rica was sustainable prior to 1990/1 but not sustainable thereafter when EF became greater than the biocapacity.
\nThe resource booklet provides information on Costa Rica. Use the resource booklet and your own studies to answer the following.
\nWith reference to the information in the resource booklet, to what extent has Costa Rica’s aim to become carbon neutral led to a more environmentally-sustainable nation?
\nThis question requires Resource booklet-May 2022 SL Paper 1, available under the “your tests” tab > supplemental materials.
\nEvidence for [4 max]:
\nAward [5 max] for evidence for and evidence against.
\nConclusion/opinion [1 max]
For example: Although Costa Rica produces most of its electricity from renewable sources, non-renewable resources are still used eg oil which is a finite resource and is not sustainable for the future;
Despite reducing loss of forest/increasing sinks for carbon, the biocapacity continues to decline and hence overall Costa Rica is not sustainable;
While Costa Rica still has some issues relating to emissions of GHGs through agriculture/transport, it is moving in the right direction towards environmental sustainability with its tree planting campaigns/increase in protected areas and cleaner air due to renewable energy sources;
A valid conclusion should be credited if it is explicit, balanced (addresses both sides of the argument) and supported by evidence. Do not credit the conclusion if only one side of the argument has been considered within the overall response.
Accept other reasonable responses supported by the information in the resource booklet.
\nMost candidates achieved 2 or 3 marks for this question. There were some excellent responses that achieved the full 6 marks but also a number of poor responses achieving no marks. Some responses inappropriately repeated material from the resource booklet without connecting the facts provided to the question being asked. Few candidates were able to provide a well-balanced conclusion. Many conclusions were either one sided or vague.
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