Ecosystems — Paper 2 · A Level Environmental Management (AS only) 8291

2 (a) A lake is an example of an ecosystem. (i) State what is meant by the term ecosystem. … … [1] (ii) An ecosystem is influenced by abiotic and biotic factors. Choose one abiotic factor and one biotic factor from the list and explain the influence of each factor in the ecosystem. competition oxygen predators minerals food availability water carbon dioxide disease pH temperature population density light abiotic factor … … … … … biotic factor … … … … … [6] (b) Fig. 2.1 shows a succession from open water in a lake, (an aquatic ecosystem), to dry land (a terrestrial ecosystem). open water aquatic vegetation A aquatic ecosystem time B sediment C terrestrial ecosystem Fig. 2.1 With reference to Fig. 2.1, describe how a shallow lake can gradually change over time from open water (an aquatic ecosystem) to dry land (a terrestrial ecosystem). … … … … … … … … … … [5] (c) Fig. 2.2 shows a photograph of a lake ecosystem and a sketch map of the surrounding area. F Key lake trees cut down drainage ditch reeds (wetland) natural woodland managed woodland grazing land cropland footpath access road river FH farmhouse FH F fishing Fig. 2.2 (i) Outline the benefits of conserving a lake ecosystem. … … … … … … [3] (ii) Suggest ways in which a lake and surrounding area can be managed for conservation. Refer to Fig. 2.2 in your answer. … … … … … … … … … … [5] [Total: 20]

20 marks

Mark scheme: 2(a)(i) (interactions between) a community of organisms / eq. and the environment / eq.; 1 Question Answer Marks 2(a)(ii) One mark for an abiotic factor and one mark for a biotic factor. Two marks for the influence on the ecosystem. (Max. 2 × 2) abiotic factor: light / carbon dioxide / water / oxygen / pH / minerals / temperature; biotic factor: predators / population density / competition for resources / food availability / disease; Accept other valid explanations of the influences. Examples may include: light: (light energy is transferred to chemical energy by) photosynthesis; food produced by the primary producers of the ecosystem; carbon dioxide / water: used as raw materials in the process of photosynthesis; in primary productivity of the ecosystem; (Accept acidification effects.) water: medium for organisms; in which to carry out life processes within the ecosystem – to move, reproduce, etc.; oxygen: used in (aerobic) respiration; to release energy (by living organisms in the ecosystem); pH / temperature: effect rate of chemical reactions; species tolerance to these factors will determine the species composition of the ecosystem; minerals: are required for plant growth; productivity of the ecosystem; 6 Question Answer Marks 2(a)(ii) predators: predators consume prey; have a predator-prey feeding relationship and control population size in the ecosystem; population density: affects availability of food, nesting sites etc.; competition for resources in the ecosystem; food availability / disease: determines population size of organisms; determines biodiversity of the ecosystem; Allow ECF if factor incorrectly identified as biotic / abiotic. 2(b) a change in the community as the environment changes / a hydrosere; organic material / sediment builds up in the lake / increasing sedimentation; water becomes shallower / the lake gradually fills in / less open water / area dries out / increased evaporation; abiotic factors / environment change during succession; e.g. moisture content of sediment / soil; aquatic species are gradually replaced by marsh / wetland species; eventually the area becomes less favourable to aquatic organisms / more favourable to terrestrial organisms; grasses / herbaceous plants / shrubs colonise / grow; eventually a woodland / climax forest is established; colonising from the surrounding terrestrial ecosystem; Credit ref. to climate change and transition to drier environment. 5 Question Answer Marks 2(c)(i) Credit one mark for each of three different benefits or award additonal marks for development of a benefit or an example. Max. of two marks for one area. For example: ecological; e.g. habitat for aquatic species / niches / nesting sites / breeding ground for amphibians / maintaining biodiversity; aesthetic; e.g. beauty of the landscape; education; e.g. awareness of the importance of food chains / webs; recreation; e.g. boating; walking / relaxation; economic; e.g. harvesting of reeds; fishing; tourism; as a water resource; environmental; e.g. flood protection; moral; e.g. preventing extinction of species; 3 Question Answer Marks 2(c)(ii) Allow ref. to management of the lake or surrounding area or both. Examples may include: management of surrounding area: control of pollution, e.g. run-off from fields; control of nutrient input into the lake; timing of fertiliser treatment on the agricultural land; quantity of fertilisers applied; planting buffer strips along agricultural land and stream / river; to absorb nutrients / reduce nutrient load; to prevent eutrophication; maintenance of drainage ditches; removing silt / sediment build-up; to maintain flow and prevent flooding; selective logging in managed woodland; coppicing; afforestation of felled areas; replanting native species; management of lake: control algae blooms; oxygenation of water; reed cutting on edge of lake to maintain open water; management of wetland area; to prevent succession; 5 Question Answer Marks 2(c)(ii) monitoring fish numbers; maintaining fish stocks; control of invasive species; to reduce competition from non-native species; other conservation strategies, e.g.: monitoring; control of visitor numbers; allow research / educational field trips / studies; controlled access to site, e.g. entry permits; fishing permits; clearing debris; legislation, with examples; establish lake ecosystem as a protected area; e.g. nature reserve / country park;

This question in 8291/21 May/June 2017

1 (a) Fig. 1.1 shows a pyramid of biomass with three trophic levels. trophic level 3 trophic level 2 trophic level 1 Fig. 1.1 (i) What is meant by the terms biomass and trophic level ? biomass … … trophic level … … [2] (ii) State the names of the trophic levels shown in Fig. 1.1. trophic level 3 … trophic level 2 … trophic level 1 … [3] (iii) Describe the relationship between the trophic levels shown in the pyramid in Fig. 1.1 and explain its shape. … … … … … … … … [4] (b) Fig. 1.2 shows the change in percentage coral cover on Caribbean coral reefs from 1973 to 2010. 60 50 40 percentage coral cover 30 20 10 0 1970 1980 1990 2000 2010 year Fig. 1.2 (i) Using the data from Fig. 1.2, describe the change in percentage coral cover from 1973 to 2010. … … … … … … [3] (ii) Suggest how human activities can contribute to the loss of coral cover. … … … … … … … … … … … … … … … … [8] [Total: 20]

20 marks

Mark scheme: 1(a)(i) biomass: (dry) mass / grams of living organisms (per unit area / ecosystem); trophic level: feeding level in a food chain / food web; 2 1(a)(ii) trophic level 3: secondary consumers / carnivores; trophic level 2: primary consumers / herbivores; trophic level 1: producers / plants / organisms containing chlorophyll / chloroplasts / autotrophic organisms; 3 1(a)(iii) organisms at trophic level 1 (autotrophs / producers) produce food by photosynthesis (using sunlight energy); trophic levels 2 and 3 contain organisms (consumers / heterotrophs) that obtain energy through feeding on other organisms; organisms at a higher trophic level feed on the organisms at the level / levels below / organisms at TL 3 feed on organisms at TL 2 / organisms at TL 2 are eaten by organisms at TL 3 / organisms at TL 1 are eaten by organisms at TL 2; biomass decreases at each trophic level as less energy is transferred through the trophic levels from TL 1 to higher levels; but energy decreases through the trophic levels as less energy is available as a result of energy losses from the food chain at each trophic level; e.g., in excretion / movement / not all of the organism is consumed; energy is lost to the environment in respiration; 4 Question Answer Marks 1(b)(i) overall decrease 1973 to 2010 / trend shows a fall in coral cover over time; use of data to support, e.g. approx. 58% highest value to approx. 10% so approx. 48% loss; fluctuations / anomalies in overall decrease noted; ref. to initial increase in coral cover for short period; 3 1(b)(ii) Award one mark for each suggested human activity which can contribute to coral loss. (Max. of four for a list of activities.) Award marks for development and exemplification of how the activity contributes to coral loss. (Max. of four marks for any one activity developed and exemplified.) For example: pollution of the marine environment; example of organic or inorganic pollution, e.g. fertiliser from agriculture; oil; heavy metals; plastics; run-off / siltation; increase in non-coral algae / reduction in coral algae; damaging fishing activities, e.g. blast fishing / dynamite fishing; overfishing; ref. to relevant effect on potential food web / food chain affecting coral cover; coastal development; construction; placing material over coral reefs; extraction, e.g. dredging / digging navigation channels; for shipping / boat access; blasting / coral mining for building materials; destroys coral reef; tourism effects; boating / diving; untreated sewage from hotels etc.; 8 Question Answer Marks 1(b)(ii) coral harvesting; e.g. use in jewellery; e.g. use in fish tanks etc.; burning of fossil fuels; increasing carbon dioxide levels / rising of sea levels / climate change; ocean warming; acidification; coral bleaching;

This question in 8291/22 May/June 2017

4 Fig. 4.1 shows a mangrove ecosystem, which is an example of a coastal water ecosystem. mangrove vegetation high tide marine life low tide Fig. 4.1 (a) With reference to the ecosystem shown in Fig. 4.1, describe how two biotic and two abiotic factors influence the structure of the ecosystem. [10] (b) With reference to examples, assess the effectiveness of international protocols and organisations that have been important in highlighting the preservation of the biosphere. [30] [Total: 40]

40 marks

Mark scheme: 4(a) Biotic factors include, for example, the mangrove vegetation and the marine life. The growth of mangrove roots provides a framework for sedimentation of organic matter which traps nutrients and provides a substrate for other organisms to colonise. The mangrove vegetation carries out photosynthesis – primary productivity. Producers transfer energy from sunlight, produce oxygen and biomass and determine the productivity and trophic structure of the ecosystem. The vegetation also provides habitats, niches, food and nesting sites and therefore influences the biodiversity of the ecosystem. There are feeding relationships between the marine life in food chains and food webs, at the different trophic levels of producers, herbivores and carnivores. There are predator and prey relationships and there is competition between the organisms which influence the population density of species in the ecosystem. Abiotic factors include, for example, the water level and tides. The water level / depth of water can restrict the growth of mangrove roots and affect the oxygen concentration of the water and thus the respiration of the aquatic organisms. Different mangrove vegetation / organisms can tolerate different water depths with differing degrees of exposure to the air and have varying tolerance to desiccation. The tides also affect the salinity of the water. Different species of mangrove vegetation have varying degrees of salt tolerance. Please use level descriptors 1 10 Question Answer Marks 4(b) The question requirements are: • to use examples relevant to preservation of the biosphere • to refer to the role of international protocols and organisations • to assess the effectiveness of the international protocols and organisations in preservation of the biosphere. Indicative content: International protocols, for example, the agreement signed at the Earth Summit in Rio in 1992 – UN Conference on Environment and Development have highlighted the need to preserve the biosphere. Both species and pollution cross national borders and trade in endangered species is also international. Oceans do not have borders and pollution from one side of the globe can affect the other side of the world; hence protocols are required to preserve the biosphere. However individual countries will still want to protect their own interests, not all nations are in agreement or signed the treaty and action plans needed to follow up the initial commitment have not been carried out. International conservation organisations include, for example the IUCN – International Union for Conservation of Nature, the WWF – World Wide Fund for Nature. Organisations such as these help in highlighting issues and in formulating the agreements between countries / governments. They are important in publicising environmental information, for example the list of threatened species and in raising charitable funds to help carry out action plans. Although effective to some extent there are still problems, for example, the continued loss of habitat and the illegal trade. Examples of biomes could include tropical rainforests or different ecosystem types, for example, coral reefs. Specific animals or species can also be used to assess the effectiveness of organisations and protocols. Please use level descriptors 2 30

This question in 8291/22 May/June 2017

1 (a) Fig. 1.1 shows a pyramid of biomass with three trophic levels. trophic level 3 trophic level 2 trophic level 1 Fig. 1.1 (i) What is meant by the terms biomass and trophic level ? biomass … … trophic level … … [2] (ii) State the names of the trophic levels shown in Fig. 1.1. trophic level 3 … trophic level 2 … trophic level 1 … [3] (iii) Describe the relationship between the trophic levels shown in the pyramid in Fig. 1.1 and explain its shape. … … … … … … … … [4] (b) Fig. 1.2 shows the change in percentage coral cover on Caribbean coral reefs from 1973 to 2010. 60 50 40 percentage coral cover 30 20 10 0 1970 1980 1990 2000 2010 year Fig. 1.2 (i) Using the data from Fig. 1.2, describe the change in percentage coral cover from 1973 to 2010. … … … … … … [3] (ii) Suggest how human activities can contribute to the loss of coral cover. … … … … … … … … … … … … … … … … [8] [Total: 20]

20 marks

Mark scheme: 1(a)(i) biomass: (dry) mass / grams of living organisms (per unit area / ecosystem); trophic level: feeding level in a food chain / food web; 2 1(a)(ii) trophic level 3: secondary consumers / carnivores; trophic level 2: primary consumers / herbivores; trophic level 1: producers / plants / organisms containing chlorophyll / chloroplasts / autotrophic organisms; 3 1(a)(iii) organisms at trophic level 1 (autotrophs / producers) produce food by photosynthesis (using sunlight energy); trophic levels 2 and 3 contain organisms (consumers / heterotrophs) that obtain energy through feeding on other organisms; organisms at a higher trophic level feed on the organisms at the level / levels below / organisms at TL 3 feed on organisms at TL 2 / organisms at TL 2 are eaten by organisms at TL 3 / organisms at TL 1 are eaten by organisms at TL 2; biomass decreases at each trophic level as less energy is transferred through the trophic levels from TL 1 to higher levels; but energy decreases through the trophic levels as less energy is available as a result of energy losses from the food chain at each trophic level; e.g., in excretion / movement / not all of the organism is consumed; energy is lost to the environment in respiration; 4 Question Answer Marks 1(b)(i) overall decrease 1973 to 2010 / trend shows a fall in coral cover over time; use of data to support, e.g. approx. 58% highest value to approx. 10% so approx. 48% loss; fluctuations / anomalies in overall decrease noted; ref. to initial increase in coral cover for short period; 3 1(b)(ii) Award one mark for each suggested human activity which can contribute to coral loss. (Max. of four for a list of activities.) Award marks for development and exemplification of how the activity contributes to coral loss. (Max. of four marks for any one activity developed and exemplified.) For example: pollution of the marine environment; example of organic or inorganic pollution, e.g. fertiliser from agriculture; oil; heavy metals; plastics; run-off / siltation; increase in non-coral algae / reduction in coral algae; damaging fishing activities, e.g. blast fishing / dynamite fishing; overfishing; ref. to relevant effect on potential food web / food chain affecting coral cover; coastal development; construction; placing material over coral reefs; extraction, e.g. dredging / digging navigation channels; for shipping / boat access; blasting / coral mining for building materials; destroys coral reef; tourism effects; boating / diving; untreated sewage from hotels etc.; 8 Question Answer Marks 1(b)(ii) coral harvesting; e.g. use in jewellery; e.g. use in fish tanks etc.; burning of fossil fuels; increasing carbon dioxide levels / rising of sea levels / climate change; ocean warming; acidification; coral bleaching;

This question in 8291/23 May/June 2017

4 Fig. 4.1 shows a mangrove ecosystem, which is an example of a coastal water ecosystem. mangrove vegetation high tide marine life low tide Fig. 4.1 (a) With reference to the ecosystem shown in Fig. 4.1, describe how two biotic and two abiotic factors influence the structure of the ecosystem. [10] (b) With reference to examples, assess the effectiveness of international protocols and organisations that have been important in highlighting the preservation of the biosphere. [30] [Total: 40]

40 marks

Mark scheme: 4(a) Biotic factors include, for example, the mangrove vegetation and the marine life. The growth of mangrove roots provides a framework for sedimentation of organic matter which traps nutrients and provides a substrate for other organisms to colonise. The mangrove vegetation carries out photosynthesis – primary productivity. Producers transfer energy from sunlight, produce oxygen and biomass and determine the productivity and trophic structure of the ecosystem. The vegetation also provides habitats, niches, food and nesting sites and therefore influences the biodiversity of the ecosystem. There are feeding relationships between the marine life in food chains and food webs, at the different trophic levels of producers, herbivores and carnivores. There are predator and prey relationships and there is competition between the organisms which influence the population density of species in the ecosystem. Abiotic factors include, for example, the water level and tides. The water level / depth of water can restrict the growth of mangrove roots and affect the oxygen concentration of the water and thus the respiration of the aquatic organisms. Different mangrove vegetation / organisms can tolerate different water depths with differing degrees of exposure to the air and have varying tolerance to desiccation. The tides also affect the salinity of the water. Different species of mangrove vegetation have varying degrees of salt tolerance. Please use level descriptors 1 10 Question Answer Marks 4(b) The question requirements are: • to use examples relevant to preservation of the biosphere • to refer to the role of international protocols and organisations • to assess the effectiveness of the international protocols and organisations in preservation of the biosphere. Indicative content: International protocols, for example, the agreement signed at the Earth Summit in Rio in 1992 – UN Conference on Environment and Development have highlighted the need to preserve the biosphere. Both species and pollution cross national borders and trade in endangered species is also international. Oceans do not have borders and pollution from one side of the globe can affect the other side of the world; hence protocols are required to preserve the biosphere. However individual countries will still want to protect their own interests, not all nations are in agreement or signed the treaty and action plans needed to follow up the initial commitment have not been carried out. International conservation organisations include, for example the IUCN – International Union for Conservation of Nature, the WWF – World Wide Fund for Nature. Organisations such as these help in highlighting issues and in formulating the agreements between countries / governments. They are important in publicising environmental information, for example the list of threatened species and in raising charitable funds to help carry out action plans. Although effective to some extent there are still problems, for example, the continued loss of habitat and the illegal trade. Examples of biomes could include tropical rainforests or different ecosystem types, for example, coral reefs. Specific animals or species can also be used to assess the effectiveness of organisations and protocols. Please use level descriptors 2 30

This question in 8291/23 May/June 2017

2 (a) Fig. 2.1 shows part of a food web for a coral reef ecosystem. reef shark angelfish pufferfish butterflyfish crown-of-thorns sea sponge fan worm starfish zooplankton green turtle microscopic photosynthetic algae in coral seagrass filamentous phytoplankton coral algae Fig. 2.1 (i) From Fig. 2.1, identify one organism at: the first trophic level … the second trophic level … the third trophic level. … [2] (ii) Suggest the role of the microscopic photosynthetic algae living within the coral, as shown in Fig. 2.1. … … … … [2] (iii) With reference to Fig. 2.1, describe and explain one effect of an increase in the number of crown-of-thorns starfish on the amount of coral. … … … … [2] (iv) With reference to Fig. 2.1, explain one effect of overfishing in the seas around the coral reefs. … … … … [2] (b) Fig. 2.2 shows the threats to and the impact of human activity on coral reefs. The map is divided into two regions, region A South East Asia and region B Australia and Papua New Guinea. Pacific region Ocean A S.E.S.E. AsiaAsia region B PapuaPapua NewNew Indian GuineaGuinea Ocean Australia Key threats fishing pollution coral harvesting tourism impact on the coral percentage in region percentage in region reefs A B already destroyed 37 2 critical 28 3 threatened 27 15 at low threat 8 80 Fig. 2.2 (i) With reference to Fig. 2.2, compare the threats to and the impact of human activity on the coral reefs in region A and region B. … … … … … … … … … … … … [6] (ii) Describe and explain methods that can be used to preserve and conserve coral reefs. … … … … … … … … … … … … [6] [Total: 20]

20 marks

Mark scheme: 2(a)(i) e.g.: 1st trophic level: sea grass / filamentous algae / phytoplankton / photosynthetic algae; 2nd trophic level: green turtle / zooplankton / butterfly fish / coral / reef shark; 3rd trophic level: sea sponge / fan worm / coral / reef shark; 2 2 / 3 trophic levels correct for 2 marks 1correct for 1 mark. Allow algae. 2(a)(ii) absorb sunlight energy; produce (organic) food (photosynthesis); nutrients for coral organisms; symbiotic relationship; 2 No mark for photosynthesis alone; 2(a)(iii) reduced size of coral (colony) / decreased amount of coral; increased predation of coral; more feeding by crown-of thorns starfish; 2 2(a)(iv) reduced fish stock / declining fish populations; reduces food source for higher level consumers / tertiary consumers; reduces the number of primary consumers (or named); less consumption of filamentous algae / increasing non-coral algae; increased competition for light / nutrients; decrease in the algae associated with coral; less competition for the crown-of-thorns starfish for coral; increasing population of predatory crown-of-thorns starfish; destructive fishing methods damaging the coral; 2 Question Answer Marks Guidance 2(b)(i) Threats: A (South East Asia) has greater overall threat with a higher number of threats; compared to B (Australia and Papua New Guinea) with fewer threats; In A (South East Asia) mainly due to threats from fishing; and more threats in every category of threat (fishing, pollution, coral harvesting, tourism) – use of data from map; compared to in B in Papua New Guinea with the largest threat from pollution from land, followed by tourism in Australia and (dynamite) fishing in Papua New Guinea; no coral harvesting in B; Impact: A greater overall impact (reference to data); largest % of coral reefs already destroyed and large % of critical and threatened and lowest % of low impact (8%); B has less impact with the largest % in the low risk category (80%); lower % in all other categories of already destroyed, critical and threatened (20%); 6 Answer must be comparative. Award a max of 4 for either threats or impacts. Question Answer Marks Guidance 2(b)(ii) restricting coastal developments which cause sedimentation on the reefs; sediment damages the coral colonies; increased turbidity reduces light for the coral algae; reducing land based sources of marine pollution; reducing nutrient input into to the sea by reducing fertilisers from agricultural runoff; reducing sewage from domestic sources; excess nutrients encourage the growth of non-coral algae which outcompete the coral algae; reducing marine based pollution by; impose fishing regulations; reducing the exploitation of the coral reef organisms; ban the use of dynamite / cyanide in fishing ; control human marine activities; restrict areas of boating / snorkelling to minimise damage to coral; educate the public; establish protected areas to preserve species and protect habitats; national park / marine park / conservation area; zones for different uses e.g. recreation, shipping ; monitoring the coral: 6

This question in 8291/21 Oct/Nov 2017

3 Fig. 3.1 is a diagram representing energy flow and nutrient recycling in an ecosystem. energy out of the ecosystem tertiary consumers secondary consumers energy from detritivores the Sun and decomposers primary consumers producers Key nutrient biomass store energy flow nutrient recycling Fig. 3.1 (a) With reference to Fig. 3.1, describe the flow of energy and the recycling of nutrients in an ecosystem. [10] (b) Describe the impact of deforestation on forest ecosystems. Using examples, assess the strategies used to reduce the pressures on forest ecosystems. [30] [Total: 40]

40 marks

Mark scheme: 3(a) Energy enters the ecosystem as sunlight energy, is transferred by photosynthesis to chemical energy in primary productivity and transferred through the trophic levels from producers to consumers when one organism feeds on another, in food chains. Energy is also transferred to the detritivores and decomposers. At each trophic level energy is lost from the ecosystem as heat in respiration. Nutrients are absorbed from the soil by plants, assimilated and passed along the food chains when one organism feeds on another. Dead plants and animals are broken down by detritivores, decomposed by decomposers and the nutrients released into the soil. Both energy and nutrients transfer through food chains. Energy flows through the ecosystem while, nutrients are recycled. Please use level descriptors 1 10 Question Answer Marks Guidance 3(b) The question requirements are: • to describe the impacts of deforestation on terrestrial ecosystems • to describe strategies to reduce the human impact upon ecosystems • to assess the strategies • to use examples Indicative content: Deforestation impacts upon the forest ecosystem through loss of habitat and loss of food supply nesting and breeding sites for the community of organisms. Declining populations result in a loss of biodiversity, with species becoming vulnerable, threatened and at risk of extinction. Deforestation also impacts the forest environment by affecting climate and the hydrological cycle, for example through reduced evapotranspiration. Soil is impacted through increased surface run-off and the nutrient cycles are affected by increased leaching of soil, soil erosion and soil degradation. Strategies to reduce the impact of deforestation include the sustainable use of forest resources for example through selective logging in timber managed areas or agroforestry, by maintaining the forest but using the land for growing a suitable crop. Establishing protected forest reserves, preventing the illegal logging of specific species and afforestation of fragmented forest areas can be effective strategies. Education by emphasising the benefits of maintaining forest cover and associated wildlife and encouraging ecotourism for the economic value of the forest are alternative strategies. Please use level descriptors 2 30

This question in 8291/21 Oct/Nov 2017

1 (a) Fig. 1.1 shows the relationship between precipitation and temperature for some major biomes. 4500 4000 3500 A 3000 average annual precipitation 2500 / mm 2000 temperatetemperate 1500 deciduousdeciduous forestforest 1000 savannahsavannah grassland 500 C B 0 –20 –15 –10 –5 0 5 10 15 20 25 30 average annual temperature / °C Fig. 1.1 (i) State what is meant by the term biome. … … [1] (ii) Use Fig. 1.1 to name the biomes labelled A, B and C. A … B … C … [2] (iii) Use Fig. 1.1 to state the range of temperature and precipitation within the temperate deciduous forest biome. range of temperature … range of precipitation … [2] (iv) State one factor, other than temperature and precipitation, which determines the distribution of the major biomes. … … [1] (v) Suggest why the boundaries between some of the biomes shown in Fig. 1.1 overlap. … … … … [2] (b) Fig. 1.2 shows the stores and the flows of nutrients within a tropical rainforest ecosystem. In this diagram the sizes of the circles and the width of the arrows are proportional to the quantity of nutrients. Key B B biomass P L litter S soil Le leaching W weathering R run-off L P precipitation S flow of nutrients Le store of nutrients R W Fig. 1.2 (i) With reference to Fig. 1.2, describe how the nutrient balance of a tropical rainforest ecosystem is maintained. … … … … … … … … [4] (ii) Fig. 1.3 shows three different ways human activity impacts on tropical rainforest ecosystems. photograph X photograph Y photograph Z Fig. 1.3 Describe the impacts of human activity on tropical rainforest ecosystems. Refer to Fig. 1.2 and Fig. 1.3 in your answer. … … … … … … … … … … … … … … … … [8] [Total: 20]

20 marks

Mark scheme: 1(a)(i) regional, biotic community characterised by a dominant form of vegetation type (and distinct climate); 1 Allow large scale ecosystem. 1(a)(ii) A Tropical rainforest; B Desert; C Tundra; 2 1 mark for any 1 correct. 2 marks for any 2 / 3 correct. 1(a)(iii) temperature range: between 1.5 degrees centigrade to 21 degrees centigrade; precipitation range: between 520 mm to 2350 mm; 2 Accept a range from just above 0–2 and 20–21. Accept a correct calculated difference. Accept a range from 500–600 and 2300–2400. Accept a correct calculated difference. 1(a)(iv) latitude / altitude / soil; 1 1(a)(v) conditions do not usually change abruptly; there is a gradual change in climate .e.g. becoming drier / wetter; transition in terms of vegetation from one biome to another; 2 Accept a well described example e.g. desert to savannah grassland / shrub-land to forest. 1(b)(i) input of nutrients from precipitation is greater than output by runoff; nutrient flow from the biomass to the litter store together with the nutrient input from precipitation, is balanced with the flow of nutrients to the soil store; balanced with the uptake of nutrients by the vegetation from the soil store; vegetation / biomass have proportionally the largest nutrient store compared to soil / litter; (rapid) decomposition of dead plant material and incorporation into soil; (rapid) uptake of nutrients and incorporation into biomass; or (rapid) recycling of nutrients; inputs from weathering equal losses by leaching; 4 Question Answer Marks Guidance 1(b)(ii) human activity impacting on the forest: photograph X : part of the forest is cleared by burning / slash and burn; for subsistence agriculture; photograph Y : large tracts of forest are clear-cut by logging for; urban development / infrastructure / mining / commercial agriculture (e.g. oil palm plantation); photograph Z : the forest is largely deforested; replaced with grass for cattle-ranching; impacts on the community of organisms in the ecosystem: fragmentation of habitats; loss of habitats; reduction in food supply; loss of nesting / breeding sites; loss of biodiversity; a wide range of species threatened with risk of extinction; impacts on the environment on the hydrological cycle / climate: reduced evapotranspiration; reduced precipitation; carbon sink reduction; increased surface run-off; impact on soil: removal of the biomass store; removes input to litter store; reduces soil nutrient store; increased leaching of nutrients; soil erosion / soil degradation; soil compaction by trampling; 8 Max.6 marks if there is no reference to Fig.1.3. or Fig.1.2.

This question in 8291/22 Oct/Nov 2017

1 (a) Fig. 1.1 shows the flows and stores of nutrients in a tropical rainforest ecosystem. biomass leaf fall uptake by plants precipitation weathering litter soil 13% of 14% of nutrients nutrients run-off decomposition leaching Key store of nutrients flow of nutrients input / output Fig. 1.1 (i) Calculate the percentage of nutrients stored in biomass in the tropical rainforest ecosystem shown in Fig. 1.1. … % [1] (ii) State what is meant by the term biomass. … … [1] (iii) With reference to Fig. 1.1, describe the interactions between the stores of nutrients within a tropical rainforest ecosystem. … … … … … … [3] (iv) Explain how precipitation influences the stores and flows of nutrients in a tropical rainforest ecosystem. … … … … … … … … [4] (v) Explain why more nutrients are stored in biomass than in the litter and soil in a tropical rainforest. … … … … … … [3] (b) Fig. 1.2 shows human activities that lead to deforestation of a tropical rainforest. 5% other* 10% logging 20% large-scale 45% small-scale commercial agriculture agriculture (oil palm) 20% pasture (cattle ranching) *other includes urbanisation, mining, construction of roads and dams Fig. 1.2 (i) Describe the ways in which the human activities shown in Fig. 1.2 affect the nutrient cycle in the tropical rainforest shown in Fig. 1.1. … … … … … … … … … … [5] (ii) Suggest ways in which the impact of human activities on tropical rainforest ecosystems can be reduced. … … … … … … [3] [Total: 20]

20 marks

Mark scheme: 1(a)(i) 73%; 1 1(a)(ii) (mass of) living / biotic / organic (components of the ecosystem) (per unit area / ecosystem); mass of living organisms, in a given area, measured in grams per square metre; 1 1(a)(iii) nutrients are recycled in the ecosystem; (inorganic compounds / nutrients) from the soil are absorbed by plant roots into the plant; assimilation (into organic compounds) / (secondary) productivity; growth; stored as wood / new biomass; dead leaves / dead organisms / leaf fall are incorporated into leaf litter; leaf litter is broken down / decays; due to the action of detritivores / microbial action; humus formation; nutrients are released into the soil store as (inorganic compounds / minerals) soil is enriched; 3 Question Answer Marks 1(a)(iv) precipitation outputs: run-off, removes nutrients (dissolved in precipitation); leaching removes nutrients from the soil store by; percolation to groundwater; precipitation inputs: nutrients, dissolved in rainfall; e.g. nitrite; throughfall / interception / leaf drip / stem flow; infiltration of rainwater into soil store; nutrients dissolved in solution; allows the uptake of nutrients by plants; by diffusion / active transport; used in plant growth and stored in biomass; (chemical weathering) of bedrock releases nutrients into the soil store; 4 1(a)(v) rapid rate of decomposition of (organic material); due to increased rate of microbial activity; high temperature and high humidity / rainfall provide optimum conditions for this (rapid decomposition); rapid incorporation of nutrients into humus; rapid recycling of nutrients / nutrients spend a relatively short time period in litter and soil; longevity / nutrients are incorporated by organisms over a long period of time in growth; 3 Question Answer Marks 1(b)(i) removal of the biomass; increased surface run-off; increased nutrient loss from soil store; increased leaching of soil; soil erosion / soil degradation; the destruction of the vegetation results in loss of habitat; loss of food supply; loss of nesting and breeding sites for the community of organisms; declining populations; biodiversity loss / species are vulnerable / threatened / at risk of extinction; effect on climate / hydrological cycle, e.g.; a change in rates of evaporation / evapotranspiration; a change in precipitation rate; risk of flooding; subsistence agriculture has the highest percentage use (45%) but has less effect on the nutrient cycles; the ecosystem can be restored through natural succession; only small fragmented areas are used; nutrients are replenished through nutrient recycling; the effect of logging (10%) will be dependent on the type of logging / area of land involved; cattle ranching (20%) / plantation (20%) have greater effect due to removal of biomass from large areas; overgrazing; soil compaction by trampling; pasture land has less effect on nutrient cycles, as the ground is covered with vegetation and soil cover is maintained (compared to plantation where the soil is part exposed during the growing season) / and manure is added; although the lowest percentage of deforestation (5%) is from the ‘others’ category, e.g. mining, dams, these have a greater effect due to complete removal of biomass and soil pollution; 5 Question Answer Marks 1(b)(ii) sustainable agriculture in conservation areas; e.g. agroforestry which combines using the land for growing a suitable crop within the forest thus maintaining the forest; use crop rotation; subsistence agriculture using small fragmented areas with sufficient time for natural succession; sustainable use of forest resources; selective logging in timber managed areas; removing some trees from forest while maintaining the overall forest as opposed to clear cutting large areas; preventing the illegal logging of specific species; afforestation; of fragmented forest areas; re-growing the forest; protected areas / protected forest reserves; national parks; restricting impact of human activity by, e.g.; raising awareness through education of the economic value of and benefits of maintaining forest cover and its associated wildlife; ecotourism; 3

This question in 8291/21 May/June 2018

2 (a) Fig. 2.1 shows part of a natural forest ecosystem before deforestation. Fig. 2.2 shows agriculture on the same land after deforestation. precipitation precipitation nutrients in forest tree biomass canopy interception nutrients are removed nutrients in when the crop crops is harvested heavy run-off nutrients in light run-off leaf litter and soil shallow roots deep roots heavy leaching light leaching Before deforestation Agriculture after deforestation Fig. 2.1 Fig. 2.2 (i) State one abiotic and one biotic component in a natural forest ecosystem. abiotic … biotic … [2] (ii) With reference to Fig. 2.1, describe how the biotic and abiotic components of a natural forest ecosystem interact. … … … … … … … … [4] (iii) With reference to Fig. 2.1 and Fig. 2.2, explain the environmental effects of deforestation and then using the land for agriculture. … … … … … … … … [4] (b) Fig. 2.3 shows agroforestry. This is one way of changing the agricultural system to be more sustainable. In agroforestry, crops are grown as part of a forest ecosystem. coffee crops Fig. 2.3 Describe and explain how agroforestry can help restore and conserve forest ecosystems. Refer to Fig. 2.1, Fig. 2.2 and Fig. 2.3 in your answer. … … … … … … … … … … [5] (c) Another strategy for conserving a forest ecosystem sustainably is to encourage ecotourism. Outline the benefits of ecotourism in the sustainable development of ecosystems. … … … … … … … … … … [5] [Total: 20]

20 marks

Mark scheme: 2(a)(i) abiotic; e.g. soil / water / light / nutrient; biotic: e.g. trees / plants / vegetation / microorganisms / fungi; 2 2(a)(ii) Light and plants: light is absorbed by leaves; primary productivity / photosynthesis; energy is transferred in food chains; minerals and plants: plant absorb minerals / nutrients from soil; used for growth / secondary productivity; stored as biomass; temperature and decomposers: leaf litter provides food for decomposers / detritivores; process of decomposition returns nutrients to soil; higher temperatures increase the rate of microbial action and thus rate of decomposition; precipitation and trees: weathering of parent rock releases nutrients; nutrients are dissolved in solution; tree roots absorb nutrients from the soil; water and vegetation: vegetation cover prevents excessive run-off; water from precipitation infiltrates the soil; plants absorb water from the soil in roots 4 Question Answer Marks 2(a)(iii) loss of nutrients from the ecosystem; as nutrients are removed from the ecosystem when a crop is harvested; nutrients are not recycled; there are no deep roots to utilise nutrients from the weathering of bedrock and increased leaching; loss of soil fertility; the soil surface is more exposed; there is often no permanent vegetation cover / the vegetation cover is reduced; increased runoff results in soil erosion / soil degradation; removal of vegetation / biomass; habitat destruction; 4 2(b) maintains / restores some natural vegetation; provides habitats for organisms; food chains / webs / niche; conserves / increases biodiversity; preserves natural predators of pests; reduces need for artificial pesticides; organic matter is introduced through as leaf fall; (organically) fertilises the soil; reduces need for (artificial) fertilisers; maintains a hydrological / soil balance; permanent vegetation cover; reduces soil exposure / increase soil stability / reduces wind erosion; other economic benefits; co-operation between land use for agriculture and logging; 5 Question Answer Marks 2(c) supports nature conservation; offers environmental benefits; protects ecological balance; reduces pressure on natural resources; economic benefits; natural unspoilt areas have a value; provides opportunities for income generating activities; e.g. game reserve entrance fees / safari tours; helps create job opportunities for locals e.g. employment as rangers / guides; diversifies the economy; improves the income levels for locals; money raised can be used for the maintenance and management of the areas; for conservation / environmental management projects; socio-cultural benefits; local traditions are preserved; local community can be involved in providing services e.g.; educate the public on conservation; 5

This question in 8291/22 May/June 2018

2 (a) Fig. 2.1 shows part of a natural forest ecosystem before deforestation. Fig. 2.2 shows agriculture on the same land after deforestation. precipitation precipitation nutrients in forest tree biomass canopy interception nutrients are removed nutrients in when the crop crops is harvested heavy run-off nutrients in light run-off leaf litter and soil shallow roots deep roots heavy leaching light leaching Before deforestation Agriculture after deforestation Fig. 2.1 Fig. 2.2 (i) State one abiotic and one biotic component in a natural forest ecosystem. abiotic … biotic … [2] (ii) With reference to Fig. 2.1, describe how the biotic and abiotic components of a natural forest ecosystem interact. … … … … … … … … [4] (iii) With reference to Fig. 2.1 and Fig. 2.2, explain the environmental effects of deforestation and then using the land for agriculture. … … … … … … … … [4] (b) Fig. 2.3 shows agroforestry. This is one way of changing the agricultural system to be more sustainable. In agroforestry, crops are grown as part of a forest ecosystem. coffee crops Fig. 2.3 Describe and explain how agroforestry can help restore and conserve forest ecosystems. Refer to Fig. 2.1, Fig. 2.2 and Fig. 2.3 in your answer. … … … … … … … … … … [5] (c) Another strategy for conserving a forest ecosystem sustainably is to encourage ecotourism. Outline the benefits of ecotourism in the sustainable development of ecosystems. … … … … … … … … … … [5] [Total: 20]

20 marks

Mark scheme: 2(a)(i) abiotic; e.g. soil / water / light / nutrient; biotic: e.g. trees / plants / vegetation / microorganisms / fungi; 2 2(a)(ii) Light and plants: light is absorbed by leaves; primary productivity / photosynthesis; energy is transferred in food chains; minerals and plants: plant absorb minerals / nutrients from soil; used for growth / secondary productivity; stored as biomass; temperature and decomposers: leaf litter provides food for decomposers / detritivores; process of decomposition returns nutrients to soil; higher temperatures increase the rate of microbial action and thus rate of decomposition; precipitation and trees: weathering of parent rock releases nutrients; nutrients are dissolved in solution; tree roots absorb nutrients from the soil; water and vegetation: vegetation cover prevents excessive run-off; water from precipitation infiltrates the soil; plants absorb water from the soil in roots 4 Question Answer Marks 2(a)(iii) loss of nutrients from the ecosystem; as nutrients are removed from the ecosystem when a crop is harvested; nutrients are not recycled; there are no deep roots to utilise nutrients from the weathering of bedrock and increased leaching; loss of soil fertility; the soil surface is more exposed; there is often no permanent vegetation cover / the vegetation cover is reduced; increased runoff results in soil erosion / soil degradation; removal of vegetation / biomass; habitat destruction; 4 2(b) maintains / restores some natural vegetation; provides habitats for organisms; food chains / webs / niche; conserves / increases biodiversity; preserves natural predators of pests; reduces need for artificial pesticides; organic matter is introduced through as leaf fall; (organically) fertilises the soil; reduces need for (artificial) fertilisers; maintains a hydrological / soil balance; permanent vegetation cover; reduces soil exposure / increase soil stability / reduces wind erosion; other economic benefits; co-operation between land use for agriculture and logging; 5 Question Answer Marks 2(c) supports nature conservation; offers environmental benefits; protects ecological balance; reduces pressure on natural resources; economic benefits; natural unspoilt areas have a value; provides opportunities for income generating activities; e.g. game reserve entrance fees / safari tours; helps create job opportunities for locals e.g. employment as rangers / guides; diversifies the economy; improves the income levels for locals; money raised can be used for the maintenance and management of the areas; for conservation / environmental management projects; socio-cultural benefits; local traditions are preserved; local community can be involved in providing services e.g.; educate the public on conservation; 5

This question in 8291/23 May/June 2018

1 (a) Fig. 1.1 is a diagram of a mangrove ecosystem, which is an example of a coastal water ecosystem. muddy roots of mangrove trees soil coastal inland water high tide changing water low tide level white black red sea mangrove tree mangrove trees mangrove trees grass Fig. 1.1 (i) With reference to Fig. 1.1, state two components of a mangrove ecosystem. … … [2] (ii) With reference to Fig. 1.1, suggest two effects of the changing water level between high tide and low tide on the mangrove ecosystem. … … … … [2] (b) Table 1.1 shows the estimated global mangrove area between 1980 and 2010. Table 1.1 year 1980 1990 2000 2010 estimated global mangrove 18.79 16.93 15.74 15.23 area / million ha (i) With reference to Table 1.1, describe the changes in estimated global mangrove area between 1980 and 2010. … … … … [2] (ii) Using the data in Table 1.1, calculate the difference in estimated global mangrove area between 1980 and 2010 as a percentage. Show your working. … % [2] (iii) Explain reasons why coastal water ecosystems, such as mangrove ecosystems, are at risk. … … … … … … … … [4] (c) Fig. 1.2 shows restoration of a mangrove ecosystem. Fig. 1.2 (i) With reference to Fig. 1.2, briefly explain what is meant by ecosystem restoration. … … … … [2] (ii) Briefly explain two benefits of conserving coastal water ecosystems, such as mangrove ecosystems. … … … … … … … … [4] (iii) Suggest one benefit of community involvement in conservation of ecosystems. … … … … [2] [Total: 20]

20 marks

Mark scheme: 1(a)(i) vegetation / trees; water; soil; max 2 1(a)(ii) transition / zonation of the vegetation (with different types of mangrove adapted to the varying conditions); roots of the mangrove trees (have alternating periods of exposure to air and submergence in water); water is saline / brackish ( mangrove trees are salt tolerant / adapted to increased levels of salinity); soil is waterlogged / oxygen deficient (mangrove trees have aerial roots / breathing roots, so oxygen can diffuse from the air into these roots); mangrove tree roots (buttress, prop roots, stilt) are adapted to provide support in muddy / soft soil; max 2 1(b)(i) decrease in mangrove coverage; use or manipulation of data: e.g. the largest decrease occurs between 1980 and 1990 / 1.86 million hectares; 2 1(b)(ii) (18.79 – 15.23) = 3.56; 3.56 / 18.79 × 100 = 18.95%; 2 Question Answer Marks 1(b)(iii) (coastal water ecosystems are at risk from) human activity / natural events which destroy / disrupt / damage the ecosystem; reasons: coastal water ecosystems are used for aquaculture; rivers flowing into the ecosystem are dammed; water is drained artificially; (water cleared so) the land can be used agriculture / coastal development; timber is cut for fuelwood / charcoal industries; climate change / increase in tropical storms / increase in sea level / flooding; water pollution due to e.g. sewage/nutrients from agriculture; explanation: biodiversity is reduced; ecosystem balance / ecosystem stability is disrupted; water flow / water levels are changed; removing coastal vegetation increases coastal erosion; max 4 1(c)(i) through human intervention / conservation activities; a degraded ecosystem is improved / a destroyed ecosystem is replaced; e.g. trees are planted; organisms bred in captivity / native species are re-introduced; invasive species are removed; max 2 Question Answer Marks 1(c)(ii) any two benefits explained: filters run-off from land; reducing pollution of coastal water; provides habitats; maintains species / biodiversity; provides niche; feeding sites / breeding grounds / nesting sites for birds / nursery for fish or other organisms; sediment is trapped; stabilising roots / soil; provides storm / flood / shore protection; against tsunamis / tidal surges; max 4 1(c)(iii) less destruction / less degradation of the ecosystem; through increased education / environmental awareness; or economic benefits; through an increase in fishing stock / preventing overfishing; or incentive to further conserve; through positive feedback / as benefits to the community become apparent; max 2

This question in 8291/21 Oct/Nov 2018

2 (a) Fig. 2.1 is a map of a region of the North West Pacific and a graph showing total input of nitrogen compounds into the sea for the areas marked on the map. Nitrogen compounds can be used as an indicator of the amount of pollution in water. RUSSIA CHINA Peter the Great Bay N. KOREA Toyama Bay S. KOREA Jinhae Bay JAPAN Northwest Kyushu sea area 0 1000 km 20 000 Key 18 000 input from waste water 16 000 input from rivers 14 000 12 000 total input of nitrogen compounds 10 000 (tonnes per year) 8 000 6 000 4 000 2 000 0 Northwest Toyama Bay, Jinhae Bay, Peter the Kyushu Japan South Korea Great Bay, sea area, Russia Japan Fig. 2.1 (i) Using Fig. 2.1, state which area receives the highest total input of nitrogen compounds from waste water. … … [1] (ii) Using Fig. 2.1, calculate the total input of nitrogen compounds from rivers per year into the four areas. … tonnes of nitrogen per year [2] (iii) Name the process in which pollution of lakes by compounds containing nitrogen and phosphorus leads to algal blooms. … [1] (iv) Explain how the process named in 2(a)(iii) leads to the loss of biodiversity. … … … … … … … … … … … … [6] (v) Suggest two human activities that lead to the pollution of water stores. 1. … … 2. … … [2] (b) Fig. 2.2 shows part of a food web for the North West Pacific region shown in Fig. 2.1. shark tuna dolphin sardines small fish crabs lobster zooplankton shrimp phytoplankton Fig. 2.2 (i) State two primary consumers shown in Fig. 2.2. … … [2] (ii) Tuna are becoming endangered in this region. Suggest two possible effects of this on the food web shown in Fig. 2.2. … … … … [2] (iii) Marine ecosystems are under threat from a range of human activities. Suggest strategies to manage these threats and to conserve these important habitats. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 2(a)(i) Northwest Kyushu sea area 1 2(a)(ii) 26 200; 5200 + 10 000 + 6000 + 5000 or 5000 + 10 000 + 6000 + 5000 or 5000 + 10 000 + 6000 + 4900 or 5200 + 10 000 +6000 + 4900; 2 2(a)(iii) Eutrophication; 1 2(a)(iv) increased nitrate acts as fertiliser; plant growth increases rapidly; algae are plants and grow rapidly; excess growth leads to competition for resources; example e.g. sunlight; for photosynthesis; plants / algae die; decomposition occurs; microbes consume oxygen; for respiration; oxygen levels in water depleted; (invertebrates / vertebrates) die / move away; max 6 2(a)(v) waste from cattle farms; leaks from sewage; dumping / littering; industrial leaks; overuse of chemical fertilisers; overuse of manure; long term release of sewage from leaks; run-off; max 2 Question Answer Marks 2(b)(i) zooplankton; shrimp; 2 2(b)(ii) less food for shark; increased predation of sardines / small fish; reduced feeding on zooplankton; increased population of zooplankton; more food for shrimp / small fish; max 2 2(b)(iii) monitoring; international cooperation; legislation; fines; education; fisheries management; marine conservation zone; cleaning up pollution events; max 4

This question in 8291/21 May/June 2019

2 (a) The Great Barrier Reef is the world’s largest coral reef ecosystem. Fig. 2.1 shows the areas of the Great Barrier Reef monitored for bleaching in 2016 and 2017. Bleaching events turn the coral white due to the death of algae within coral. 2016 2017 N N Key most severe bleaching no or negligible bleaching Cairns Cairns Townsville Townsville Mackay Mackay 0 500 0 500 km km Fig. 2.1 (i) Describe two differences in the coral bleaching in 2016 and 2017 shown in Fig. 2.1. … … … … [2] (ii) Suggest two human activities which could directly cause damage to the coral. … … … … [2] (b) Fig. 2.2 is an extract from a report about coral bleaching of the Great Barrier Reef. Aerial surveys have found that two severe bleaching events in 2016 and 2017 affected two- thirds of the Great Barrier Reef. This phenomenon is mainly caused by increases to the sea surface temperature. Scientists using aerial surveys recorded bleaching at 800 individual coral reefs across 8,000 km. The results show the two consecutive mass bleaching events have affected a 1,500 km stretch, leaving only the reef’s southern third undamaged. The 2017 event spread further south, and was most intense in the middle section of the Great Barrier Reef. The 2017 mass bleaching, second in severity only to 2016, has occurred even in the absence of an El Niño event. Mass coral bleaching has occurred on the reef four times in recorded history. Fig. 2.2 (i) With reference to Fig. 2.2, explain what has led to the mass bleaching of the coral. … … … … [2] (ii) Suggest two ways, other than aerial surveys, scientists monitor changes in the coral reef. 1 … … 2 … … [2] (c) Fig. 2.3 is part of a food web for a coral reef such as the Great Barrier Reef. sea eagle reef shark sea turtle large fish jellyfish sea horse small fish molluscs coral zooplankton krill phytoplankton Fig. 2.3 (i) With reference to Fig. 2.3, suggest the effects that an increase in jellyfish numbers might have on this coral reef food web. … … … … … … … … … [4] (ii) The Crown of Thorns Starfish is an invasive predatory species which feeds on coral. Suggest how an invasion by these starfish might affect the food web shown in Fig. 2.3. … … … … … … … … [4] (iii) Suggest strategies to control the population of the Crown of Thorns Starfish. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 2(a)(i) more areas of severe bleaching; previously affected areas (2016) are larger; damage spreading further north / south; southern area remains undamaged; max 2 2(a)(ii) diving; boating damage (contact); boating damage from nets / lines / anchors; pollution; named pollutant; coral mining; overfishing; max 2 2(b)(i) increased global warming / climate change; leads to rising sea temperatures; El Nino affects sea temperature; and leads to increased bleaching; complex chemical changes in the water lead to increased coral bleaching; acidification; max 2 2(b)(ii) satellite imaging; aerial photos; dive monitoring; monitoring of sea temperatures; colour chart testing; max 2 2(c)(i) increased phytoplankton; decreased zooplankton; reduction in small fish; reduction in molluscs; increased coral; food web becomes unbalanced; likely increase in top predators / reef shark / sea eagle; max 4 Question Answer Marks 2(c)(ii) damage / kill large areas of coral; reduce biodiversity of coral; less coral available for secondary consumers; reduction in species in the food web; named example; less food for top predators; loss of habitat / shelter for species in the food web; max 4 2(c)(iii) collection / removal by divers; allows reduction of numbers and provides opportunities to inspect the progress / state of the reef; kill by chemical injections; some concern over chemicals entering the food web; disrupt reproduction with hormones; population gradually declines as reproduction rate falls; introduce predatory fish; these eat the starfish but could interfere with the food web; a robot has been designed to catch and inject the starfish; less need for human interaction with the reef and the species there; max 4

This question in 8291/22 May/June 2019

2 (a) The Great Barrier Reef is the world’s largest coral reef ecosystem. Fig. 2.1 shows the areas of the Great Barrier Reef monitored for bleaching in 2016 and 2017. Bleaching events turn the coral white due to the death of algae within coral. 2016 2017 N N Key most severe bleaching no or negligible bleaching Cairns Cairns Townsville Townsville Mackay Mackay 0 500 0 500 km km Fig. 2.1 (i) Describe two differences in the coral bleaching in 2016 and 2017 shown in Fig. 2.1. … … … … [2] (ii) Suggest two human activities which could directly cause damage to the coral. … … … … [2] (b) Fig. 2.2 is an extract from a report about coral bleaching of the Great Barrier Reef. Aerial surveys have found that two severe bleaching events in 2016 and 2017 affected two- thirds of the Great Barrier Reef. This phenomenon is mainly caused by increases to the sea surface temperature. Scientists using aerial surveys recorded bleaching at 800 individual coral reefs across 8,000 km. The results show the two consecutive mass bleaching events have affected a 1,500 km stretch, leaving only the reef’s southern third undamaged. The 2017 event spread further south, and was most intense in the middle section of the Great Barrier Reef. The 2017 mass bleaching, second in severity only to 2016, has occurred even in the absence of an El Niño event. Mass coral bleaching has occurred on the reef four times in recorded history. Fig. 2.2 (i) With reference to Fig. 2.2, explain what has led to the mass bleaching of the coral. … … … … [2] (ii) Suggest two ways, other than aerial surveys, scientists monitor changes in the coral reef. 1 … … 2 … … [2] (c) Fig. 2.3 is part of a food web for a coral reef such as the Great Barrier Reef. sea eagle reef shark sea turtle large fish jellyfish sea horse small fish molluscs coral zooplankton krill phytoplankton Fig. 2.3 (i) With reference to Fig. 2.3, suggest the effects that an increase in jellyfish numbers might have on this coral reef food web. … … … … … … … … … [4] (ii) The Crown of Thorns Starfish is an invasive predatory species which feeds on coral. Suggest how an invasion by these starfish might affect the food web shown in Fig. 2.3. … … … … … … … … [4] (iii) Suggest strategies to control the population of the Crown of Thorns Starfish. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 2(a)(i) more areas of severe bleaching; previously affected areas (2016) are larger; damage spreading further north / south; southern area remains undamaged; max 2 2(a)(ii) diving; boating damage (contact); boating damage from nets / lines / anchors; pollution; named pollutant; coral mining; overfishing; max 2 2(b)(i) increased global warming / climate change; leads to rising sea temperatures; El Nino affects sea temperature; and leads to increased bleaching; complex chemical changes in the water lead to increased coral bleaching; acidification; max 2 2(b)(ii) satellite imaging; aerial photos; dive monitoring; monitoring of sea temperatures; colour chart testing; max 2 2(c)(i) increased phytoplankton; decreased zooplankton; reduction in small fish; reduction in molluscs; increased coral; food web becomes unbalanced; likely increase in top predators / reef shark / sea eagle; max 4 Question Answer Marks 2(c)(ii) damage / kill large areas of coral; reduce biodiversity of coral; less coral available for secondary consumers; reduction in species in the food web; named example; less food for top predators; loss of habitat / shelter for species in the food web; max 4 2(c)(iii) collection / removal by divers; allows reduction of numbers and provides opportunities to inspect the progress / state of the reef; kill by chemical injections; some concern over chemicals entering the food web; disrupt reproduction with hormones; population gradually declines as reproduction rate falls; introduce predatory fish; these eat the starfish but could interfere with the food web; a robot has been designed to catch and inject the starfish; less need for human interaction with the reef and the species there; max 4

This question in 8291/23 May/June 2019

5 Fig. 5.1 is a diagram that represents the stages in a succession. Time Fig. 5.1 (a) Describe and explain the stages of succession in a named habitat. [10] (b) Using examples, assess how political and economic factors affect the success of conservation strategies. [30] [Total: 40]

40 marks

Mark scheme: 5(a) Two types of succession are primary (from bare soil and rock) and secondary (after an environmental event such as flood or volcano activity). The origin of the succession is also a factor leading to hydrosere, xerosere or lithosere, for example. Answer should include the appropriate stages of succession for the choice made and provide some explanation of the causes of the changes at each stage, such as formation of litter to improve fertility leading to more advanced species which then outcompete the pioneer species before further development leads to climax community please use level descriptors 1 10 5(b) The question requirements are: • to understand that conserving habitats at different stages of succession is important such as wetlands • to demonstrate understanding of different methods of conservation • to assess the success of the different strategies. Indicative content: Some plagioclimax habitats are key habitats for rare species especially wetlands and marshes or have key roles such as coastal sand dunes. As a result it is important for these to be conserved at these stages of succession to preserve the habitats and the species biodiversity. A range of schemes considered to include national parks, conservation areas, SSSI, wildlife parks, marine parks, ecotourism and ecological islands. Details of the individual schemes and how they operate to include legislation, education, staffing and the nature of work carried out. The principles behind the schemes and methods used plus the potential problems. Assessment of the relative success of each scheme described linked to the effects on the habitats and species therein as well as the balance between conservation and the use by the human population. please use level descriptors 2 30 Section B descriptor levels: Descriptor Award Mark Consistently meets the level criteria Mark at top of level Meets the criteria, but with some inconsistency Middle, mark to just below top mark Meets most of level criteria, but not all convincingly Just below middle, mark to just above bottom mark On the borderline of this level and the one below Mark at bottom of level Section B descriptor levels: Section B (part (a)): 8–10 marks The response: • contains few errors • shows a very good understanding of the question • shows a good use of data or the information provided, where appropriate • provides a balanced answer 5–7 marks The response: • may contain some errors • shows an adequate understanding of the question • shows some use of data or the information provided, where appropriate • may lack balance 1–4 marks The response: • may contains errors • shows limited understanding of the question • shows little or no use of data or the information, where appropriate • lacks balance Level descriptors 1 Section B descriptor levels: Section B (part (b)): Responses: Level one, 25–30 marks • fulfil all the requirements of the question • contain a very good understanding of the content required • contain a very good balance of content • contain substantial critical and supportive evaluations • make accurate use of relevant vocabulary Level two, 19–24 marks • fulfil most of the requirements of the question • contain a good understanding of the content required • contain a good balance of content • contain some critical and supportive evaluations • make good use of relevant vocabulary Level three, 13–18 marks • fulfil some requirements of the question • contain some understanding of the content required • may contain some limited balance of content • may contain brief evaluations • make some use of relevant vocabulary Level four, 6–12 marks • fulfil limited requirements of the question • contain limited understanding of the content required • may contain poorly balanced of content • may not contain evaluations • make limited use of relevant vocabulary Level descriptors 2 Section B descriptor levels: Level five, 1–5 marks • fulfil a few of the requirements of the question • contain a very limited understanding of the content required • are likely to be unbalanced and undeveloped • evaluative statements are likely to be missing • make no use of relevant vocabulary

This question in 8291/21 Oct/Nov 2019

1 (a) Fig. 1.1 is a diagram showing energy flow through an ecosystem. energy from the sun gross primary production respiration net primary production feeding consumers respiration death excretion X respiration Fig. 1.1 (i) State what X represents in Fig. 1.1. … [1] (ii) Use Fig. 1.1 to explain the difference between gross primary production and net primary production. … … … … [2] (iii) State two abiotic factors that affect the rate of primary productivity. 1. … 2. … [2] (iv) Name the process by which primary producers synthesise organic molecules using energy from the sun. … [1] (v) State the biome with the highest net primary productivity. … [1] (b) Fig. 1.2 is a pyramid of biomass for a temperate deciduous forest food chain. wolves (420 kg / km2) red foxes (2 100 kg / km2) snowshoe hares (20 925 kg / km2) grass (2.0925 x 107 kg / km2) Fig. 1.2 (i) State the primary consumer shown in Fig. 1.2. … [1] (ii) Describe what a pyramid of biomass shows. … … … … [2] (iii) Explain the shape of the pyramid of biomass shown in Fig. 1.2. … … … … [2] (iv) If the population of wolves decreased, state and explain two changes that could occur in the food chain shown in Fig. 1.2. … … … … … … … … [4] (c) Fig. 1.3 shows the nutrient flows and stores for a temperate deciduous forest. biomass precipitation Key Y size of circle proportional to the size of the nutrient store litter width of arrow proportional to the amount of soil nutrient flow leaching run-off weathering Fig. 1.3 (i) Describe the method by which nutrients flow in the process labelled Y on Fig. 1.3. … [1] (ii) With reference to Fig. 1.3, describe the changes which might occur to the forest nutrient stores and flows as a result of deforestation. … … … … … … [3] [Total: 20]

20 marks

Mark scheme: 1(a)(i) decomposition / decay; 1 1(a)(ii) (gross primary production) is all the production; minus the energy used in respiration; 2 1(a)(iii) temperature; moisture / water; sunlight; carbon dioxide; max 2 2 1(a)(iv) photosynthesis; 1 1(a)(v) tropical rainforest; 1 1(b)(i) (snowshoe) hare; 1 1(b)(ii) the mass of organism / species; at each trophic level; the amount of energy available; at each trophic level; the transfer of energy; between trophic levels; max 2 2 1(b)(iii) only energy stored; is transferred; energy is lost; as heat / due to respiration / other wastes; max 2 2 Question Answer Marks 1(b)(iv) red foxes would increase; because of less predation; snowshoe hares would suffer more predation; population would decrease; resulting in more grass; max 4 4 1(c)(i) absorption; 1 1(c)(ii) large amount of stored biomass lost / reduced; as trees are felled; less input / flow into the litter; litter store will decrease; run-off will increase; less flow from litter to soil; less flow from soil to biomass; weathering of soil increases; max 3 3

This question in 8291/22 Oct/Nov 2019

5 Fig. 5.1 shows the relationship between average annual precipitation and temperature for some major biomes. 4500 4000 3500 tropical 3000 rainforest average annual precipitation 2500 / mm 2000 temperatetemperate 1500 deciduousdeciduous forestforest 1000 savannahsavannah grassland 500 polarpolar desertdesert 0 –20 –15 –10 –5 0 5 10 15 20 25 30 average annual temperature / °C Fig. 5.1 (a) Describe how biotic and abiotic factors control the distribution of the biomes shown in Fig. 5.1. [10] (b) Using examples, assess conservation methods used to maintain biodiversity in ecosystems. [30] [Total: 40]

40 marks

Mark scheme: 5(a) Abiotic factors such as light, temperature and moisture influence the tolerance of species determining the limits of where they can survive and as a result the different biomes are formed. These can also be considered limiting factors. Biotic factors include supply of food, competition through predation, for space and resources. Humans have a large effect including agricultural practices, building and introducing species to new areas. please use level descriptors 1 10 5(b) The question requirements are: • to show knowledge of ecosystems • to show knowledge of different methods of conservation methods relative to maintaining biodiversity • to assess the relative success of such methods. Indicative content: Selection of relevant ecosystem. The different methods of conservation could include National parks, nature reserves, SSSIs, zoos and safari parks. Breeding and release programmes. Education and involvement of local population, ecotourism, controlled hunting including bans and seasons, and use of legislation. Appropriate descriptions of the methods chosen and assessment of relative success. Issues raised could include problems of poaching, loss of land to local people unless they are involved, economics of protection, difficulties of enforcement, political will and education. please use level descriptors 2 30 Section B descriptor levels Descriptor Award Mark Consistently meets the level criteria Mark at top of level Meets the criteria, but with some inconsistency Middle, mark to just below top mark Meets most of level criteria, but not all convincingly Just below middle, mark to just above bottom mark On the borderline of this level and the one below Mark at bottom of level Section B descriptor levels Section B (part (a)): 8–10 marks The response: • contains few errors • shows a very good understanding of the question • shows a good use of data or the information provided, where appropriate • provides a balanced answer 5–7 marks The response: • may contain some errors • shows an adequate understanding of the question • shows some use of data or the information provided, where appropriate • may lack balance 1–4 marks The response: • may contains errors • shows limited understanding of the question • shows little or no use of data or the information, where appropriate • lacks balance Level descriptors 1 Section B descriptor levels Section B (part (b)): Responses: Level one, 25–30 marks • fulfil all the requirements of the question • contain a very good understanding of the content required • contain a very good balance of content • contain substantial critical and supportive evaluations • make accurate use of relevant vocabulary Level two, 19–24 marks • fulfil most of the requirements of the question • contain a good understanding of the content required • contain a good balance of content • contain some critical and supportive evaluations • make good use of relevant vocabulary Level three, 13–18 marks • fulfil some requirements of the question • contain some understanding of the content required • may contain some limited balance of content • may contain brief evaluations • make some use of relevant vocabulary Level four, 6–12 marks • fulfil limited requirements of the question • contain limited understanding of the content required • may contain poorly balanced of content • may not contain evaluations • make limited use of relevant vocabulary Level descriptors 2 Section B descriptor levels Level five, 1–5 marks • fulfil a few of the requirements of the question • contain a very limited understanding of the content required • are likely to be unbalanced and undeveloped • evaluative statements are likely to be missing • make no use of relevant vocabulary

This question in 8291/22 Oct/Nov 2019

1 (a) Fig. 1.1 shows the relationships between nutrient flows and stores for three biomes, P, Q and R. biome P biome Q biome R X X B X B B L L L Y Y Y S S S Key size of arrow, circle and letter indicate size of flow or store flow of nutrients B – biomass store L – litter store S – soil store Fig. 1.1 (i) Identify the biomes in Fig. 1.1 using the terms listed. desert temperate forest tropical rainforest biome P … biome Q … biome R … [2] (ii) State the process labelled X in Fig. 1.1. … [1] (iii) State the process labelled Y in Fig. 1.1. … [1] (iv) Describe how deforestation affects nutrient flows and stores in a tropical rainforest. … … … … … … … [4] (b) Fig. 1.2 shows the distribution of savannah (tropical grassland). N Tropic of Cancer Equator Tropic of Capricorn Key savannah (tropical grassland) Fig. 1.2 (i) Describe the distribution of savannah (tropical grassland) shown in Fig. 1.2. … … … … [2] (ii) State the two main abiotic factors which lead to the distribution shown in Fig. 1.2. 1 … 2 … [2] (iii) Wildfires are needed to help maintain the stability of the savannah (tropical grassland) ecosystem. Suggest two advantages and two disadvantages of wildfires. advantages … … … … disadvantages … … … … [4] (iv) Explain two strategies, other than the use of fire, which manage and conserve the biodiversity of savannah (tropical grassland). … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 1(a)(i) P temperate forest (taiga); Q desert; R tropical rainforest; max 2 1(a)(ii) precipitation / rain(fall); 1 1(a)(iii) decomposition / decay; 1 1(a)(iv) biomass store reduced; due to removal of trees; litter store reduced; no leaves to fall; surface run-off increases; no trees to act as flow reducers; reduction in rainfall; due to reduction in evapotranspiration; soil moisture reduces; soil erosion increases; loss of canopy causes reduces phosphorus levels; less CO2 taken up by photosynthesis; less organic nitrogen (due to erosion and leaching); max 4 1(b)(i) near the equator; (almost entirely) between the tropics; Africa / South America / India / Australia; max 2 1(b)(ii) temperature; rainfall / water; 2 Question Answer Marks 1(b)(iii) advantages: destroys excessive growth; clears / creates space for growth; increases biodiversity; adds nutrients; destroys harmful insects / disease causing species; disadvantages: threatens human habitation; affects livestock; reduces soil litter layer; can spread out of control (catastrophic wildfire); can alter the soil surface structure which increases the chance of flash flooding; haze/smog; affects breathing; max 4 1(b)(iv) sustainable methods are used in order to protect the environment; improved conservation education programmes for local communities and farmers; harvesting branches rather than whole trees to prevent deforestation, soil erosion and desertification; crop rotation to keep a varied supply of nutrients in the soil and prevent soil erosion and desertification; stone lines along the soil contours keep it in place, prevent erosion and improve crop yields; managing grazing land to avoid overgrazing, soil erosion and desertification; decreasing livestock – solves the problem of overgrazing but requires people to adapt if they rely on cattle or goats for their livelihoods; establish protected areas; encourage indigenous species / discourage use of introduced species; encourage ecotourism; local people employed by conservation and tourism schemes; max 4

This question in 8291/21 May/June 2020

2 (a) Fig. 2.1 shows the distribution of the tundra biome. Arctic Circle, 66.5 °N Tropic of Cancer, 23.5 °N Equator Tropic of Capricorn, 23.5 °S Key tundra biome Fig. 2.1 (i) Describe the distribution of the tundra biome shown in Fig. 2.1. … … … … [2] (ii) State the two main abiotic factors which contribute to the distribution of the tundra biome shown in Fig. 2.1. 1 … 2 … [2] (b) Fig. 2.2 is a food chain found in the tundra biome. Lichen Caribou Arctic Wolf Fig. 2.2 (i) State what is represented by the arrows in the food chain shown in Fig. 2.2. … … … … [2] (ii) Suggest why food chains in the tundra biome are short. … … … … [2] (c) Fig. 2.3 is an extract from a local news webpage. With more people moving to the tundra to work in mines and on oil rigs, more towns and roads have been built. The building of other structures, such as the Trans-Alaska Oil Pipeline, have caused disruption to species such as the Arctic Wolf. In addition, pesticides have been used to control large swarms of insects, which migrating birds rely on for food in the tundra. Fig. 2.3 (i) Suggest three ways in which human activities in Fig. 2.3 have caused disruption to the habitat of the Arctic Wolf. … … … … … … [3] (ii) Explain why the use of pesticides to control insect populations might lead to the death of Arctic birds of prey. … … … … … … [3] (d) Fig. 2.4 is an extract from an environmental journal. Permafrost is a characteristic of the tundra biome. The soil is frozen to a considerable depth meaning that trees cannot grow there. The permafrost acts as a store of water, methane and carbon dioxide. The winter months of January and February 2018 saw a change in weather patterns with unusually high temperatures in the arctic tundra, leading to melting of some of the permafrost. Fig. 2.4 Explain how the melting of some of the permafrost might affect coastal communities and global weather patterns. … … … … … … … … … … [6] [Total: 20]

20 marks

Mark scheme: 2(a)(i) near the North Pole / top of the world; above 60 °N latitude; on or close to the Arctic circle; northern Canada, Alaska, northern Scandinavia and Siberia; 2(a)(ii) temperature; moisture / rainfall / precipitation; 2 Question Answer Marks 2(b)(i) the transfer of energy; from prey to predator / from one organism to another / through feeding; 2 2(b)(ii) harsh environment; short summer means abundance is very short lived; means food chains are fragile; populations are (relatively) small; biodiversity is (relatively) low; Less energy available to higher levels max 2 2(c)(i) hunting / shooting; roads disrupt territories; risk of collisions; settlements disrupt prey animals’ behaviour; populations decline / relocate; poisoning (deliberate / accidental); bioaccumulation; max 3 2(c)(ii) insects contain the poison; insectivores ingest this poison; passes along the food chain; becomes more concentrated; bioaccumulation; top predator gets lethal / damaging dose of insecticide; gyrfalcons die / have reduced reproduction; max 3 Question Answer Marks 2(d) water stored as permafrost released; leads to more water in rivers and streams; increasing likelihood of flooding; water runs into the oceans; leading to rising sea levels; causing flooding of coastal communities; increasing salinisation of coastal soils / land; melting of the permafrost releases carbon dioxide store / methane; this is no longer locked up / released into the atmosphere; extra carbon dioxide / methane leads to increase in greenhouse gases; contributes to global warming; more extreme weather patterns / global weather pattern is uncertain as could lead to feedback loops; computer models vary in their predictions of feedback loops; more storms leading to coastal damage; decrease albedo as permafrost melts; max 6

This question in 8291/22 May/June 2020

2 (a) Fig. 2.1 shows the distribution of the tundra biome. Arctic Circle, 66.5 °N Tropic of Cancer, 23.5 °N Equator Tropic of Capricorn, 23.5 °S Key tundra biome Fig. 2.1 (i) Describe the distribution of the tundra biome shown in Fig. 2.1. … … … … [2] (ii) State the two main abiotic factors which contribute to the distribution of the tundra biome shown in Fig. 2.1. 1 … 2 … [2] (b) Fig. 2.2 is a food chain found in the tundra biome. Lichen Caribou Arctic Wolf Fig. 2.2 (i) State what is represented by the arrows in the food chain shown in Fig. 2.2. … … … … [2] (ii) Suggest why food chains in the tundra biome are short. … … … … [2] (c) Fig. 2.3 is an extract from a local news webpage. With more people moving to the tundra to work in mines and on oil rigs, more towns and roads have been built. The building of other structures, such as the Trans-Alaska Oil Pipeline, have caused disruption to species such as the Arctic Wolf. In addition, pesticides have been used to control large swarms of insects, which migrating birds rely on for food in the tundra. Fig. 2.3 (i) Suggest three ways in which human activities in Fig. 2.3 have caused disruption to the habitat of the Arctic Wolf. … … … … … … [3] (ii) Explain why the use of pesticides to control insect populations might lead to the death of Arctic birds of prey. … … … … … … [3] (d) Fig. 2.4 is an extract from an environmental journal. Permafrost is a characteristic of the tundra biome. The soil is frozen to a considerable depth meaning that trees cannot grow there. The permafrost acts as a store of water, methane and carbon dioxide. The winter months of January and February 2018 saw a change in weather patterns with unusually high temperatures in the arctic tundra, leading to melting of some of the permafrost. Fig. 2.4 Explain how the melting of some of the permafrost might affect coastal communities and global weather patterns. … … … … … … … … … … [6] [Total: 20]

20 marks

Mark scheme: 2(a)(i) near the North Pole / top of the world; above 60 °N latitude; on or close to the Arctic circle; northern Canada, Alaska, northern Scandinavia and Siberia; 2(a)(ii) temperature; moisture / rainfall / precipitation; 2 Question Answer Marks 2(b)(i) the transfer of energy; from prey to predator / from one organism to another / through feeding; 2 2(b)(ii) harsh environment; short summer means abundance is very short lived; means food chains are fragile; populations are (relatively) small; biodiversity is (relatively) low; Less energy available to higher levels max 2 2(c)(i) hunting / shooting; roads disrupt territories; risk of collisions; settlements disrupt prey animals’ behaviour; populations decline / relocate; poisoning (deliberate / accidental); bioaccumulation; max 3 2(c)(ii) insects contain the poison; insectivores ingest this poison; passes along the food chain; becomes more concentrated; bioaccumulation; top predator gets lethal / damaging dose of insecticide; gyrfalcons die / have reduced reproduction; max 3 Question Answer Marks 2(d) water stored as permafrost released; leads to more water in rivers and streams; increasing likelihood of flooding; water runs into the oceans; leading to rising sea levels; causing flooding of coastal communities; increasing salinisation of coastal soils / land; melting of the permafrost releases carbon dioxide store / methane; this is no longer locked up / released into the atmosphere; extra carbon dioxide / methane leads to increase in greenhouse gases; contributes to global warming; more extreme weather patterns / global weather pattern is uncertain as could lead to feedback loops; computer models vary in their predictions of feedback loops; more storms leading to coastal damage; decrease albedo as permafrost melts; max 6

This question in 8291/23 May/June 2020

1 (a) Fig. 1.1 shows how the mass of plants changes during primary succession following a major environmental event. pine trees shrubs mass of plants grasses mosses time Fig. 1.1 (i) State one major environmental event which would lead to a primary succession. … [1] (ii) Explain why there is a long period of time before the pine trees start to colonise, as shown in Fig. 1.1. … … … … … … … … [4] (iii) Describe the difference between the origin of a primary succession and the origin of a secondary succession. … … … … [1] (b) Fig. 1.2 shows stages in a sand dune succession. biodiversity (number of species) time dune ridge pioneer climax dune slack community community Fig. 1.2 (i) Explain why, after its maximum, biodiversity decreases, as shown in Fig. 1.2. … … … … … … … … … … [4] (ii) Name two abiotic factors and describe how they differ at the pioneer stage and at the climax community stage shown in Fig. 1.2. abiotic factor … … … abiotic factor … … … [4] (iii) Explain why it is important to conserve and manage ecosystems such as the sand dune ecosystem. … … … … … … … … [4] (c) Suggest how arrested succession can occur in an ecosystem. … … … [2] [Total: 20]

20 marks

Mark scheme: 1(a)(i) lava flow; volcano eruption; retreating glacier; newly formed sand dune; abandoned strip mine / opencast mine; mining spoil / waste heap; max 1 1(a)(ii) need to establish fertile soil; pioneer species grow; die / lose leaves; leaves rot; due to decomposers; increasing nutrients in soil; more advanced species can colonise max 4 4 1(a)(iii) primary starts from lifeless region; secondary starts from area previously inhabited; valid example described; max 1 1 1(b)(i) biodiversity changes as the biotic and abiotic factors change; named examples; pioneer species bind the dune; humus is added; soil fertility increases; other soil factors change, e.g. soil water; competition between species increases; new species come in and survive / some species can’t survive; some species out-competed for nutrients / sunlight, etc.; climax community reached; climax species shade out / out-compete others; some release toxins into the soil to remove competitors; max 4 4 Question Answer Marks 1(b)(ii) temperature; more extreme in pioneer stage / cooler in climax stage; water; dry in pioneer stage / moister in climax stage; soil; dry and sandy in pioneer stage / moist and loamy in climax stage; nutrients; such as nitrate and phosphate increase as succession continues; max 4 4 1(b)(iii) unique habitat; protect rare species; maintain biodiversity; important role in coastal erosion; resist action of wind / waves; prevent salt water intrusion; reduce risk of salinization of soils; dune succession leads to fertile soil development inland; max 4 4 1(c) arrested succession caused by human interference / natural event; named example; 2

This question in 8291/21 Oct/Nov 2020

2 (a) Fig. 2.1 is a theoretical graph of population growth. carrying capacity of environment population time Fig. 2.1 (i) Define carrying capacity. … … … … [2] (ii) Describe the changes in population over time shown in Fig. 2.1. … … … … [2] (b) Fig. 2.2 shows the global population and annual population growth rate from 1900 to 2050 (predicted). 10.0 2.5 9.0 8.0 2.0 7.0 predicted global 6.0 1.5 annual population 5.0 population (billions) growth 4.0 1.0 rate (%) 3.0 2.0 0.5 1.0 0.0 0.0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 year Key global population annual population growth rate (%) Fig. 2.2 (i) Describe the predicted trends in global population and annual population growth rate from 2021 to 2050 shown in Fig. 2.2. … … … … [2] (ii) Suggest two factors which are likely to lead to the predicted trends shown in Fig. 2.2. … … … … [2] (iii) Malthus predicted a limit to human population growth. Suggest reasons why this has not happened. … … … … … … … … [4] (c) Fig. 2.3 shows population pyramids for two countries, A and B, with contrasting levels of economic development. males females age males females H85 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 5 4 3 2 1 0 1 2 3 4 5 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 percentage of population percentage of population country A country B Fig. 2.3 (i) Explain the differences in the shape of the two population pyramids shown in Fig. 2.3. … … … … … … … … [4] (ii) Explain why country B is likely to experience a rapid increase in population in the future. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 2(a)(i) The number of people (animals or crops) a region can support; without degradation; 2 2(a)(ii) starts off with a gradual increase; has a rapid growth rate / exponential; levels off / plateaus; max 2 2 2(b)(i) population continues to grow / rises / increases; annual growth rate is falling / decreases; 2 Question Answer Marks 2(b)(ii) falling fertility rate / birth rate / birth control campaign; increasing life expectancy / falling death rate / improved health service; 2 2(b)(iii) Malthus predicted a population catastrophe due to famine / war / disease; this hasn’t happened due to improved agricultural practices; leading to better nutrition / greater availability of food; improved medical facilities / availability; leading to better health / life expectancy; wars tend to be limited in size due to technology; less deaths relatively; more control over fertility; max 4 4 2(c)(i) Country A More like a column shape; age groups are more even; population is ageing; people live longer; females live longer than males; Country B more like a pyramid shape; much greater population at younger age group; people don’t live as long; no gender difference in longevity; max 4 4 2(c)(ii) more young people / children in the population; will reach reproductive age / mature; at the same time; produce children; leading to population boom; max 4 4

This question in 8291/22 Oct/Nov 2020

2 (a) Fig. 2.1 shows the word equation for the process of photosynthesis in green plants. sunlight carbon dioxide + water X + oxygen Fig. 2.1 (i) State what X represents in Fig. 2.1. … [1] (ii) Sunlight is the source of energy for the process of photosynthesis. Explain how green plants use sunlight in photosynthesis. … … … … [2] (iii) Explain the effect of increased carbon dioxide on the rate of photosynthesis. … … … … … … [3] (iv) State one abiotic factor and one biotic factor that affects the growth of green plants. abiotic … biotic … [2] (b) Fig. 2.2 shows the distribution of tropical rainforest in the Americas. North N America Tropic of Cancer Equator South Tropic of America Capricorn Key distribution of tropical rainforests Fig. 2.2 (i) Describe the distribution of tropical rainforest shown in Fig. 2.2. … … … … [2] (ii) Explain why there is very little leaf litter on the floor of a tropical rainforest. … … … … … … [3] (iii) Explain why there is a large amount of biodiversity in a tropical rainforest. … … … … … … [3] (iv) Explain the effects of land clearance in an area of tropical rainforest, other than on biodiversity. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 2(a)(i) glucose / sugar / C6H12O6; 1 2(a)(ii) chloroplasts; contain chlorophyll; absorbs + sunlight / light / energy from the sun; max 2 2 2(a)(iii) (increasing carbon dioxide) increases rate of photosynthesis; but then plateaus; when something else becomes limiting factor; named example e.g. temperature; carbon dioxide eventually becomes limiting factor; only uses red and blue wavelengths; max 3 3 2(a)(iv) abiotic sunlight / energy from the sun / light; water / rain / humidity; temperature; oxygen; salinity; pH soil; magnesium / chlorophyll / named mineral; biotic producers; consumers; decomposers; predation; trampling; competition for resources; described example e.g. plants shaded from light; pollination; pests / insects; max 2 2 Question Answer Marks 2(b)(i) equatorial; north / south of equator; within / between tropics; often coastal; not in North America; max 2 2 2(b)(ii) high temperature; high moisture; ideal for decomposers / detritivores; e.g. bacteria / fungi / termites; (large amounts of litter falls) rapidly recycled / broken down; organic matter; recycled as nutrients; max 3 3 2(b)(iii) constant high abiotic factors; named factor; means high energy availability / allows increased speciation; layered structure / provides wide range of habitats; the wide floral biodiversity / provides wide range of food sources; max 3 3 Question Answer Marks 2(b)(iv) Soil removes roots; no longer bind the soil; increased erosion; soil dries / increased desertification; loss of soil fertility; Humans reduces food sources; loss of medicinal plants; loss of fuel wood; loss of home / income for indigenous peoples; cultural loss for indigenous peoples; habitat destruction; reduction in carbon intake (by young, growing trees); reduction in carbon storage (by mature trees); max 4 4

This question in 8291/21 May/June 2021

1 Fig. 1.1 shows the international border between the Caribbean countries Haiti and Dominican Republic. international border Haiti Dominican Republic Fig. 1.1 (a) (i) Describe two differences between Haiti and Dominican Republic shown in Fig. 1.1. … … … … [2] (ii) Suggest two reasons for the differences in the amount of vegetation cover shown in Fig. 1.1. … … … … [2] (iii) Explain the effect of loss of vegetation cover on soil. … … … … … … [3] (iv) Explain why biodiversity decreases when vegetation cover is lost. … … … … [2] (b) Table 1.1 shows the percentage of an area covered by rainforest between 1985 and 2020. Table 1.1 year percentage of area covered by rainforest 1985 74 2000 58 2005 50 2010 44 2020 33 (i) Plot a scatter graph using the data from Table 1.1. Include a line of best fit. 100 90 80 70 60 percentage of area covered by 50 rainforest 40 30 20 10 0 1985 1990 1995 2000 2005 2010 2015 2020 year [3] (ii) Describe the change in the percentage of the area covered by rainforest between 1985 and 2020. … … [1] (c) Fig. 1.2 shows part of a food web for the Amazon Rainforest. jaguar (mammal) three toed sloth macaw howler monkey iguana (mammal) (bird) (mammal) (reptile) fire ant (insect) caterpillar (insect) plants Fig. 1.2 (i) State the number of trophic levels in the food web shown in Fig. 1.2. … … [1] (ii) State the trophic level that has the most energy. … [1] (iii) Explain why howler monkeys are both primary and secondary consumers. … … … … [2] (d) Explain the influence of light intensity on plant productivity. … … … … … … [3] [Total: 20]

20 marks

Mark scheme: 1(a)(i) Haiti trees are missing / no trees / only small trees; (mountain) soil exposed / bare earth / appears to lack plants; small scrub bushes / grassland; lacks shelter; max 2 1(a)(ii) humans remove trees; for fuel; for agriculture / grazing land; lack of control / law enforcement; poverty; max 2 2 1(a)(iii) soil dries out; exposed to forces of erosion; example e.g. wind; no roots to bind the soil / hold it in place; reduction in litter layer; loss of fertility; max 3 3 1(a)(iv) loss of shelter; loss of food; disruption of food web; reduction in water availability; reduction in species variety / gene pool; max 2 2 1(b)(i) 3-4 points correctly plotted; 5 points correctly plotted; line of best fit accurately drawn; 3 Question Answer Marks 1(b)(ii) there has been a steep decline in the amount remaining; the line off best fit is a straight line; the rate of loss is consistent; use of figures; max 1 1 1(c)(i) five; 1 1(c)(ii) plants / producers / first / 1; 1 1(c)(iii) (they feed in) two; trophic levels; they eat plants; and insects; max 2 2 1(d) increasing light intensity; increases rate of photosynthesis; more glucose produced; increasing growth; until another factor becomes limiting; named factor; max 3 3

This question in 8291/22 May/June 2021

1 Fig. 1.1 shows the international border between the Caribbean countries Haiti and Dominican Republic. international border Haiti Dominican Republic Fig. 1.1 (a) (i) Describe two differences between Haiti and Dominican Republic shown in Fig. 1.1. … … … … [2] (ii) Suggest two reasons for the differences in the amount of vegetation cover shown in Fig. 1.1. … … … … [2] (iii) Explain the effect of loss of vegetation cover on soil. … … … … … … [3] (iv) Explain why biodiversity decreases when vegetation cover is lost. … … … … [2] (b) Table 1.1 shows the percentage of an area covered by rainforest between 1985 and 2020. Table 1.1 year percentage of area covered by rainforest 1985 74 2000 58 2005 50 2010 44 2020 33 (i) Plot a scatter graph using the data from Table 1.1. Include a line of best fit. 100 90 80 70 60 percentage of area covered by 50 rainforest 40 30 20 10 0 1985 1990 1995 2000 2005 2010 2015 2020 year [3] (ii) Describe the change in the percentage of the area covered by rainforest between 1985 and 2020. … … [1] (c) Fig. 1.2 shows part of a food web for the Amazon Rainforest. jaguar (mammal) three toed sloth macaw howler monkey iguana (mammal) (bird) (mammal) (reptile) fire ant (insect) caterpillar (insect) plants Fig. 1.2 (i) State the number of trophic levels in the food web shown in Fig. 1.2. … … [1] (ii) State the trophic level that has the most energy. … [1] (iii) Explain why howler monkeys are both primary and secondary consumers. … … … … [2] (d) Explain the influence of light intensity on plant productivity. … … … … … … [3] [Total: 20]

20 marks

Mark scheme: 1(a)(i) Haiti trees are missing / no trees / only small trees; (mountain) soil exposed / bare earth / appears to lack plants; small scrub bushes / grassland; lacks shelter; max 2 1(a)(ii) humans remove trees; for fuel; for agriculture / grazing land; lack of control / law enforcement; poverty; max 2 2 1(a)(iii) soil dries out; exposed to forces of erosion; example e.g. wind; no roots to bind the soil / hold it in place; reduction in litter layer; loss of fertility; max 3 3 1(a)(iv) loss of shelter; loss of food; disruption of food web; reduction in water availability; reduction in species variety / gene pool; max 2 2 1(b)(i) 3-4 points correctly plotted; 5 points correctly plotted; line of best fit accurately drawn; 3 Question Answer Marks 1(b)(ii) there has been a steep decline in the amount remaining; the line off best fit is a straight line; the rate of loss is consistent; use of figures; max 1 1 1(c)(i) five; 1 1(c)(ii) plants / producers / first / 1; 1 1(c)(iii) (they feed in) two; trophic levels; they eat plants; and insects; max 2 2 1(d) increasing light intensity; increases rate of photosynthesis; more glucose produced; increasing growth; until another factor becomes limiting; named factor; max 3 3

This question in 8291/23 May/June 2021

2 Fig. 2.1 shows a habitat changing over time from open water to mixed woodland. Key mixed woodland grasses and shrubs swampy ground open water sediment Fig. 2.1 (a) (i) State the process shown in Fig. 2.1. … [1] (ii) Explain the reasons for the changes shown in Fig. 2.1. … … … … … … … … … … … … [6] (iii) Explain what is meant by abiotic and biotic factors of an ecosystem. Give an example for each. abiotic … … … example … biotic … … … example … [4] (b) Table 2.1 compares subsistence farming with commercial farming. Table 2.1 factor subsistence farming commercial farming amount of produce sold low high destination of foods consumed on farm or locally high proportion processed by food manufacturers power source animals fossil fuel, electricity plant nutrition organic e.g. legumes, ash, chemical fertilisers bone, manure pest control crop rotation, intercropping commercial pesticides weed control rotations, hoeing, commercial herbicide hand picking seed from own crops from commercial grower livestock feed from own crops, fodder from commercial feed manufacturer (i) Explain how commercial farming described in Table 2.1 can lead to loss of local habitats. … … … … … … … … [4] (ii) Subsistence farmers often clear land for crops. Explain why clearing land leads to loss of biodiversity. … … … … … … [3] (iii) Describe a strategy to prevent land being cleared for crops. … … … … [2] [Total: 20]

20 marks

Mark scheme: 2(a)(i) succession; 1 2(a)(ii) sedimentation; (of) soil / minerals; dead / decaying leaves; build-up in the water; shallow water evaporates; due to temperature / wind; land begins to dry; plants colonise swampy area; soil fertility increases; shrubs and trees appear; plants attract herbivores; herbivores attract carnivores; 6 2(a)(iii) abiotic: non-living parts of the environment; valid example; biotic: living part of the environment; valid example; 4 Question Answer Marks 2(b)(i) large amounts of produce; requires large amount of land; transport / power; damages environment; overuse of fertilisers; causes eutrophication in aquatic environment; overuse of pesticides / herbicides; damage food webs / disrupt habitats; 4 2(b)(ii) deforestation / removal of plants; leads to loss of soil fertility / erosion; loss of food / shelter; causes loss of animals / emigration; disrupts food web; planting crops / monoculture reduces biodiversity; 3 2(b)(iii) education; encourage people to respect the environment; legislation; fines for deforestation; encourage ecotourism; to earn a living from the biodiversity; 2

This question in 8291/21 Oct/Nov 2021

1 (a) Table 1.1 shows the number of marine wildlife affected by marine debris in one year. Table 1.1 marine debris wildlife bottles cans lobster fishing fishing fishing plastic string other group and hooks lines nets bags and fish rope traps amphibians 1 0 0 0 3 1 6 0 1 birds 2 0 0 5 45 53 19 10 4 fish 5 1 2 1 48 11 11 7 3 invertebrates 6 2 1 1 14 12 6 13 0 mammals 0 0 0 3 6 1 6 6 1 reptiles 0 0 0 0 10 4 1 3 1 (i) State which wildlife group is affected by every type of marine debris shown in Table 1.1. … [1] (ii) State which wildlife group is most affected by marine debris shown in Table 1.1. … [1] (iii) Suggest two sources of the marine debris shown in Table 1.1. … … [2] (iv) Calculate the percentage of all mammals in Table 1.1 affected by plastic bags. … % [1] (b) Fig. 1.1 shows part of an ocean food web. killer whale tiger shark green sea turtle leatherback sea turtle squid jellyfish shrimp zooplankton sea grass phytoplankton Fig. 1.1 (i) State what the arrows in the food web shown in Fig. 1.1 represent. … … [1] (ii) Sea turtles are under threat because of plastic bag pollution in the sea. The turtles mistake the bags for jellyfish. Explain the effects of a reduction in sea turtle numbers on the food web shown in Fig. 1.1. … … … … … … … … [4] (iii) Suggest strategies to prevent plastic bag pollution reaching oceans. … … … … … … … … [4] (c) Fig. 1.2 shows the net primary productivity of different aquatic ecosystems. open ocean coastal waters lakes and streams estuaries 0 10 20 30 40 50 60 70 80 90 100 net primary productivity / arbitrary units Fig. 1.2 (i) Complete the bar chart in Fig. 1.2 to show a net primary productivity of 23 arbitrary units for lakes and streams. [1] (ii) Suggest why net primary productivity is low in open oceans. … … … … [2] (iii) An estuary is found where a river meets coastal waters. The net primary productivity of an estuary is high because there is a high concentration of nutrients. Suggest reasons why the concentration of nutrients is high. … … … … … … [3] [Total: 20]

20 marks

Mark scheme: 1(a)(i) fish; 1 1(a)(ii) birds; 1 1(a)(iii) thrown / fallen from boats; thrown / lost by fishermen; blown from land; lost from landfill; carried by streams and rivers; 2 1(a)(iv) 26 / 26.1 / 26.09; 1 1(b)(i) (the) transfer / flow / movement of energy; 1 1(b)(ii) less food for top predators; numbers decrease; less feeding on seagrass; seagrass increases; less predation on squid / jellyfish; increased numbers of squid / jellyfish; long term effect – populations stabilise; 4 1(b)(iii) education; to use plastic bags more ecologically / about their effects on sea life; charging for bags at shops; to reduce use; change to paper bags; to reduce number of bags used; legislation to reduce single-use bags; to force consumers and shops to change habits; improved recycling / re-use; to prevent them getting in the sea; 4 Question Answer Marks 1(c)(i) correct plot + correct width + shading; 1 1(c)(ii) organic material sinks to bottom of ocean floor; sunlight cannot penetrate into ocean; so no photosynthesis; cold restricts enzymes / photosynthesis (RHS); 2 1(c)(iii) river flows from land to sea; collects nutrients as it crosses the land; named example; minerals from eroding rocks; excess fertilisers; sewage spilt into rivers / septic tanks leak / waste from cattle; tides mix seawater and freshwater; churning by tidal waters; 3

This question in 8291/23 Oct/Nov 2021

2 Fig. 2.1 shows a habitat changing over time from open water to mixed woodland. Key mixed woodland grasses and shrubs swampy ground open water sediment Fig. 2.1 (a) (i) State the process shown in Fig. 2.1. … [1] (ii) Explain the reasons for the changes shown in Fig. 2.1. … … … … … … … … … … … … [6] (iii) Explain what is meant by abiotic and biotic factors of an ecosystem. Give an example for each. abiotic … … … example … biotic … … … example … [4] (b) Table 2.1 compares subsistence farming with commercial farming. Table 2.1 factor subsistence farming commercial farming amount of produce sold low high destination of foods consumed on farm or locally high proportion processed by food manufacturers power source animals fossil fuel, electricity plant nutrition organic e.g. legumes, ash, chemical fertilisers bone, manure pest control crop rotation, intercropping commercial pesticides weed control rotations, hoeing, commercial herbicide hand picking seed from own crops from commercial grower livestock feed from own crops, fodder from commercial feed manufacturer (i) Explain how commercial farming described in Table 2.1 can lead to loss of local habitats. … … … … … … … … [4] (ii) Subsistence farmers often clear land for crops. Explain why clearing land leads to loss of biodiversity. … … … … … … [3] (iii) Describe a strategy to prevent land being cleared for crops. … … … … [2] [Total: 20]

20 marks

Mark scheme: 2(a)(i) succession; 1 2(a)(ii) sedimentation; (of) soil / minerals; dead / decaying leaves; build-up in the water; shallow water evaporates; due to temperature / wind; land begins to dry; plants colonise swampy area; soil fertility increases; shrubs and trees appear; plants attract herbivores; herbivores attract carnivores; 6 2(a)(iii) abiotic: non-living parts of the environment; valid example; biotic: living part of the environment; valid example; 4 Question Answer Marks 2(b)(i) large amounts of produce; requires large amount of land; transport / power; damages environment; overuse of fertilisers; causes eutrophication in aquatic environment; overuse of pesticides / herbicides; damage food webs / disrupt habitats; 4 2(b)(ii) deforestation / removal of plants; leads to loss of soil fertility / erosion; loss of food / shelter; causes loss of animals / emigration; disrupts food web; planting crops / monoculture reduces biodiversity; 3 2(b)(iii) education; encourage people to respect the environment; legislation; fines for deforestation; encourage ecotourism; to earn a living from the biodiversity; 2

This question in 8291/23 Oct/Nov 2021

3 (a) A conservationist uses aerial photographs to estimate the population of a species of bird. Fig. 3.1 shows a drawing of the position of some birds from an aerial photograph using a grid. 1 2 3 4 5 A B C D E F G Fig. 3.1 (i) Complete Table 3.1 to record the number of birds in the grid squares A4 and D3. Table 3.1 A B C D E F G 1 3 0 3 3 1 1 1 2 6 2 3 5 5 6 3 3 4 1 5 … 7 3 5 4 … 4 4 5 7 2 7 5 3 5 3 5 8 3 5 [2] (ii) Describe the benefits and limitations of using aerial photographs to survey the population of birds. benefits … … … … limitations … … … … [4] (b) The formula shows Simpson’s index of diversity. n 2 D = 1 / -f d N n p Simpson’s index of diversity is a measure of diversity that takes into account the number of species present and the relative abundance of each species. The conservationist uses Simpson’s index of diversity to analyse data from an aerial photograph in location X. Table 3.2 shows the data from the aerial photograph for location X. Table 3.2 n = 2 n n species number of N d N n individuals Canada goose 54 0.58 0.34 sandhill crane 12 0.13 0.017 snow goose 26 0.28 0.078 bald eagle 1 0.011 0.00012 N = total number of all individuals 93 (i) Use the formula to determine a value for Simpson’s index of diversity for location X. Simpson’s index of diversity = … [2] (ii) Simpson’s index of diversity for two other locations Y and Z are shown in Table 3.3. Table 3.3 location Simpson’s index of diversity Y 0.66 Z 0.75 Compare the diversity of species in locations Y and Z. … … [1] (c) Fig. 3.2 is a drawing of a sandhill crane. Fig. 3.2 The adult sandhill crane is 80–136 cm tall and has a wingspan of over 180 cm. The conservationist wants to monitor the population of sandhill cranes using a capture-mark-recapture method. (i) Outline the capture-mark-recapture method the conservationist can use. … … … … … … [3] (ii) State two assumptions that must be made when using capture-mark-recapture data. 1 … … 2 … … [2] (d) From late February to early April over 600 000 sandhill cranes fly to the wetlands of Nebraska, in the midwest of the USA. This is called migration. The birds feed on land or in shallow marshes to fatten up before they continue their migration north to their summer breeding grounds. Fig. 3.3 shows part of a food web. eagle sandhill crane small bird frog small fish zooplankton algae plants and seeds Fig. 3.3 (i) Identify the maximum number of trophic levels in this food web. … [1] (ii) Use Fig. 3.3 to write a food chain for the sandhill crane that includes only one producer, one primary consumer and one secondary consumer. … [1] (e) Banning the hunting of sandhill cranes or requiring permits to hunt them helps to conserve the population of sandhill cranes. Fig. 3.4 shows a sign also used to help conserve the population of sandhill cranes. Fig. 3.4 Suggest why these three strategies help to conserve the population of sandhill cranes. … … … … … … [3] (f) Climate change is a threat to the sandhill crane. Suggest why climate change could decrease the population of sandhill cranes. Give reasons for your answer. … … … … … … … … [4] [Total: 23]

23 marks

Mark scheme: 3(a)(i) A4: 4; D3: 5; 2 3(a)(ii) max [4] benefits max 3: can be counted remotely; data can be checked / hard copy of data; avoids bias; large areas can be covered; automated; doesn’t harm the birds / birds not disturbed; limitations max 3: relies on photographing all the birds / birds move; need aeroplane or satellite or drone to take the images / costly; difficult to count if birds on a grid line; reliant on suitable weather conditions; reliant on lack of dense groundcover; potential distortion (due to oblique angle); difficult to identify species of bird; 4 3(b)(i) 0.44; (1 – M1 =) 0.56; 2 3(b)(ii) Z is more diverse (than Y); 1 3(c)(i) any three from: tag / named example e.g. leg rings / tags / chip; recapture idea of capture: marked AND unmarked / random capture; named method of estimating population: Lincoln index; 3 Question Answer Marks 3(c)(ii) any two from: no death / no change in survival rate; no births; no migration; sampling methods are identical to first capture; random mixing of population; 2 3(d)(i) 5; 1 3(d)(ii) algae  zooplankton  (sandhill) crane; OR plants/seeds  (sandhill) crane  eagle 1 3(e) any three from: restrict number of birds hunted / number of birds killed; restricted times/season for hunting; enables birds to reproduce; birds given time to fatten (ready for migration); (sign) education / awareness; 3 3(f) loss of habitat / wetlands dry up; alter migration; loss of other species / loss of food source / disrupt food chain; introduces, invasive species/predators; 4

This question in 8291/22 May/June 2022

1 Fig. 1.1 is a map of Mongolia. Mongolia has a total land area of 1 560 000 km2. N RUSSIA CHINA Ulaanbaatar MONGOLIA CHINA Desert Gobi 0 200 km Key capital international boundary Fig. 1.1 In 2020, the population of Mongolia was 3 170 000. (a) Mongolia has a low population density. (i) Calculate the population density for Mongolia in 2020. … people km–2 [1] (ii) Explain the challenges faced by countries with a low population density. … … … … … … … … [4] (b) Fig. 1.2 shows the age dependency ratio in Mongolia from 1960 to 2018. 110 100 90 80 age dependency ratio 70 60 50 40 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 year Fig. 1.2 The higher the ratio, the larger the dependent population compared to the working-age population. A ratio of 100 indicates that the number of dependents is exactly the same as the number of working-age people. Describe the trend shown by the data in Fig. 1.2. … … … … … … [3] (c) Fig. 1.3 shows the population pyramid for Mongolia in 2020. age male range female 100+ 95–99 90–94 85–89 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 0.2 0.15 0.1 0.05 0 0 0.05 0.1 0.15 0.2 population / million Fig. 1.3 Suggest how the shape of the population pyramid for Mongolia in 1975 was different from the 2020 shape. Give reasons for your answer. … … … … [2] (d) The Gobi Desert in Mongolia is a cold desert. Describe the climate of a cold desert biome in winter and in summer. winter … … summer … … [3] (e) The photograph in Fig. 1.4 shows an area of desert during primary succession. Fig. 1.4 (i) Suggest how the pioneer species in Fig. 1.4 colonised this area of desert. … … … … [2] (ii) Suggest the characteristics of the pioneer species in Fig. 1.4. … … … … [2] (iii) Explain how the death of pioneer species can lead to secondary succession. … … … … [2] (f) The total area of land in Mongolia is 1 560 000 km2. The area of this land covered by water in Mongolia is 10 560 km2. (i) Calculate the percentage of land area covered by water in Mongolia. percentage = … [1] (ii) Suggest why climate change can increase water insecurity in Mongolia. … … … … [2] (iii) Explain the impacts of water insecurity. … … … … … … … … [4] (g) Solar radiation management (SRM) is a theoretical strategy to reduce the impact of climate change. (i) One SRM strategy is the use of space reflectors. Outline how space reflectors could reduce the impact of climate change. … … … … [2] (ii) Suggest why some people think investing in SRM technology is more important than reducing our combustion of fossil fuels. … … [1] [Total: 29]

29 marks

Mark scheme: Question Answer Marks 1(a)(i) 2 / 2.03; 1 1(a)(ii) any four from: 4 difficult to find a partner / low marriage rates; leads to low birth rate; leads to population decline; fewer jobs in rural areas; leads to abandonment of, rural areas / agricultural land; leads to urbanisation; less economically active people / fall in GDP; less people to purchase products / services, reduces economy of country; lack of available healthcare / supply of goods / accessing amenities due to large distances between people; people have to travel large distances / transportation more costly / not enough transport available; less technological advancement / create ideas to boost economy; reduction in tourism; AVP; 1(b) any three from: 3 1960–1973: increasing age dependency ratio / decreasing number of working age people / increasing number of dependents; 1973–1975: age dependency ratio plateaus / just above 100 / number of dependents exactly the same / slightly higher than number of working-age people; 1975–2010: decreasing age dependency ratio / increasing number of working age people / decreasing number of dependents; 2010–2018: increasing age dependency ratio / decreasing number of working age people / increasing number of dependents; 1(c) any two from (for 1975): 2 narrower at old age / top; lower life expectancy; improved medical care in 2020; wider for young dependents / base; birth rate higher; 1(d) any three from: 3 winter long; cold / snowfall; temperature between –2 to –14 °C; lower rainfall; summer short; hot; low rainfall (higher than the winter); (moderately) warm summer; temperature between 21 to 26 °C; 1(e)(i) seeds / spores; 2 carried by wind / insects / animals / birds / humans; 1(e)(ii) any two from: 2 fungi / lichen; high stress tolerance / hardy / withstands harsh environment; grow quickly; tough outer layer; adapted to conserve water, e.g. waxy outer layer / spiny leaves; short / shallow roots; 1(e)(iii) any two from: 2 adds organic matter / humus; adds nutrients through decomposition; reduces competition / free up space; increases water holding capacity; 1(f)(i) 0.677 / 0.68 / 0.7; 1 1(f)(ii) any two from: 2 landlocked; few existing water sources; increased temperatures / global warming; leads to drought; climate change alters rainfall patterns; 1(f)(iii) any four from: 4 reduced crop yield / crop failure; livestock death; leads to food shortages / malnutrition / famine; leads to poverty / increase in cost of food; farmers lose income from their crops; reduced water for industrial processes / loss of manufactured goods; disrupts education (particularly girls) as take time out to collect water; dehydration from lack of water to drink; limited access to clean drinking water / forced to drink contaminated water; leads to water related illnesses / cholera / typhoid / diarrhoea; migration / refugees; 1(g)(i) mirrors in space / stratosphere; 2 reflect or reduce the amount of incoming solar radiation (reaching Earth); which reduces temperature of Earth’s surface / reduces greenhouse effect / reduces global warming; 1(g)(ii) any one from: 1 we can continue to use fossil fuels / no changes needed to our way of life; hard to reduce combustion of fossil fuels;

This question in 8291/22 Oct/Nov 2022

4 Approximately 623 million people practise open defecation. This is going to the toilet outside in fields, water bodies and open spaces. (a) Suggest why urbanisation makes open defecation more of a problem. … … … … … … [3] (b) Fig. 4.1 shows a Tiger Worm Toilet, TWT. Content removed due to copyright restrictions. Fig. 4.1 A TWT contains tiger worms that digest the faeces (toilet waste). Tiger worms eat the equivalent of their own body weight each day. Fig. 4.2 shows a tiger worm. 30 – 130 mm Fig. 4.2 (i) Tiger worms digest faeces. Name this type of feeding relationship. … [1] (ii) The wood chip bedding layer in the TWT must be kept moist to enable the worms to digest the faeces aerobically. Users of the TWT are required to flush the toilet with a cup of water after each use. The wood chip bedding layer must not become flooded. Suggest why these requirements of the TWT limit its use in some locations. … … … … [2] (iii) Suggest why chemical cleaning products must not be used to clean a TWT. … … [1] (c) The authorities in a rural community want to build more TWTs for the local people. They use a questionnaire to find out local people’s opinions on TWTs. (i) Describe a sampling method for selecting the local people for the questionnaire that reduces bias. … … … … [2] (ii) The authorities consider two types of questions for the questionnaire. type 1: questions require a yes or no answer only type 2: questions allow people to write their own answers Outline one benefit and one limitation with type 1 questions compared with type 2 questions. benefit of type 1 … … limitation of type 1 … … [2] (iii) Table 4.1 shows part of the questionnaire used to find out local people’s opinions on TWTs. Table 4.1 date: location: response question yes no Do you use a TWT? … … … In Table 4.1, write one other suitable question for this questionnaire. [1]

12 marks

Mark scheme: 4(a) any three from: 3 less open spaces (for privacy to open defecate); more people living in an area / increased population density; leads to increased risk of disease; from contaminated water / from contact with faeces; 4(b)(i) decomposer / decomposition; 1 4(b)(ii) any two from: 2 high ground water level / high water table (result in flooding); area prone to floods; area prone to drought / dry conditions; no access to water / not enough water to flush; 4(b)(iii) any one from: 1 kills the tiger worms; leaches into soil; products would kill bacteria and fungi which aid the decomposition; 4(c)(i) random; 2 (random) number generator / draw names out of a ‘hat’; OR systematic; assign everyone a number; e.g. every third house / every nth person; 4(c)(ii) any one benefit: 2 (type 1) easier to process / less data to process / less time consuming; any one limitation: limited by question asked / no idea of their opinion; 4(c)(iii) suitable yes / no question: 1 Is the TWT easy to use? Would you recommend the TWT to other people? 4(d) any one advantage: 2 cheaper / worms not needed; no need for water after use; familiar technology; easier or simpler to build; any one disadvantage: needs to be moved once full / faeces is not digested or broken down; increased risk of disease as faeces is left in the ground; difficult to dig a hole if ground rocky; pit must be deeper than TWT;

This question in 8291/22 Oct/Nov 2022

2 The Sous reservoir in the Czech Republic is a source of drinking water for 100 000 people in the region. The area has been affected by acid deposition. (a) (i) Define acid deposition. … … [1] (ii) Outline the formation of acid deposition from sulfur compounds. … … … … … … [3] (iii) Describe strategies for reducing the emissions of gases that cause acid deposition. … … … … … … [3] (b) Water samples at three locations, A, B and C, in the reservoir were analysed for pH value and sulfate concentration every month for three years. Samples of clean drinking water were also analysed. Table 2.1 shows the results. Table 2.1 sulfate concentration pH water / mg per litre source min max mean min max mean A 4.6 5.5 5.2 6.2 15.5 10.4 B 4.5 6.1 5.5 3.8 10.0 6.9 C 4.7 5.3 5.0 11.3 580.2 14.2 drinking 7.1 7.3 7.2 3.2 3.4 3.3 water (i) Calculate the pH range for water source B. range = … [1] (ii) Suggest why the maximum value recorded for sulfate concentration at water source C was not used to determine the mean value. … … [1] (iii) Use the mean data in Table 2.1 to write a conclusion about the water in the reservoir. … … … … [2] (iv) The water samples from the reservoir are collected in bottles. Suggest why each bottle is filled and then emptied with water from the reservoir six times before the final sample is taken. … … [1] (v) The sample bottles are labelled with the: • initials of the person collecting the sample • sample location • date. Suggest two other details that should be recorded to ensure the results are comparable. 1 … … 2 … … [2] (vi) Fig. 2.1 is a diagram of the Sous reservoir with the three locations, A, B and C, marked. A B C Fig. 2.1 Suggest how the sampling of water from the reservoir can be improved. … … … … [2] (c) A food chain for the reservoir is shown. plankton mayfly crayfish trout otter (i) State the producer in this food chain. … [1] (ii) State the trophic level of the mayfly. … [1] (iii) Explain how energy is lost in food chains. … … … … … … [3] [Total: 21]

21 marks

Mark scheme: 2(a)(i) idea of (atmospheric) deposits with a pH < 5.6; 1 2(a)(ii) any three from: M1 combustion or burning of fossil fuels; M2 formation sulfur dioxide or SO2 / sulfur reacts with oxygen / S + O2  SO2; M3 (their M2) gas reacts with water or H2O; M4 to form sulfuric acid / H2SO4; 3 2(a)(iii) any three strategies/developments from: M1 reduce use of fossil fuels / use renewable resources / use stated renewable resource; SO2: M2 flue gas desulfurisation / flue gas removal from chimneys; M3 fuel desulfurisation; NOx: M4 catalytic convertors; 3 Question Answer Marks 2(b)(i) 1.6; 1 2(b)(ii) anomalous data point / outlier; 1 2(b)(iii) any two from: M1 pH values similar / sulfate concentrations vary, at each location; M2 low pH / acidic pH / pH less than drinking water; M3 high (concentration of) sulfate / more (concentrated with) sulfate than drinking water; M4 idea that (reservoir) water affected by acid deposition; 2 2(b)(iv) to remove any impurities from the bottle; 1 2(b)(v) any two from: M1 time; M2 water temperature; M3 air temperature; M4 weather conditions; M5 water depth of sample; M6 volume of water collected; 2 2(b)(vi) any two from: M1 more (than 3) locations; M2 not all in one place / spread out sampling; M3 longer sampling period / more than three years of sampling / more than once a month; M4 different depths; 2 2(c)(i) plankton; 1 2(c)(ii) second; 1 Question Answer Marks 2(c)(iii) any three from: M1 lost as heat; M2 idea of only 10% of energy passed between levels / 90% is lost; lost through: M3 respiration; M4 digestion; M5 (excreted) waste (products); M6 movement; M7 death / decomposition; M8 maintaining body temperature / thermoregulation; M9 feeding / consumers do not consume the whole organism; 3

This question in 8291/21 May/June 2023

1 Plants use chlorophyll to capture light energy for photosynthesis. (a) State the word equation for photosynthesis. … [2] (b) Chemists have developed a chemical that can be added to the roots of plants to improve the efficiency of photosynthesis. In laboratory studies, the chemical increased crop yield by 20%. Suggest why increasing crop yield can improve global food security. … … … … [2] (c) Maize is a food crop. Table 1.1 shows data for world maize yield in tonnes per hectare for two years. Table 1.1 yield year / tonnes per ha 1961 1.94 2018 5.92 Calculate the percentage increase in world maize yield from 1961 to 2018. … % [2] (d) Globally, 1.3 billion tonnes of food are wasted each year. 40% of all foods require refrigeration (cold temperatures) to maintain freshness. (i) Suggest why countries with low‑income economies are less likely to use refrigeration. … … … … [2] (ii) It is estimated that 15% of fossil fuel energy is used in the global transport of refrigerated food. Describe one strategy to reduce the use of fossil fuels in transporting food. … … … … [2] (e) Genetically modified (GM) crops can help improve food security. (i) ‘Roundup Ready’ soya is a GM crop grown in North and South America. This GM crop allows farmers to spray soya plants with herbicide. The GM crop is not harmed by herbicides. Suggest the benefits and limitations of using herbicide‑resistant GM crops, such as ‘Roundup Ready’ soya. benefits … … … limitations … … … [4] (ii) GM crops are being developed to have lighter and brighter coloured leaves than other crops. The lighter and brighter leaves increase the overall albedo of the plant. Explain how increased albedo can help to counteract climate change. … … … … [2] [Total: 16]

16 marks

Mark scheme: 1(a) reactants: carbon dioxide + water; products: glucose + oxygen; 2 1(b) any two from: provides enough food to feed the current / increasing population; more food can be grown in same area of land / intensification of food production; enables, stockpiling of food / surplus food; enables (improved) distribution of food; 2 1(c) 5.92  1.94 or 3.98; 205; 2 1(d)(i) any two from: lack of money; limited access to energy / electricity / energy insecure; lack of (refrigeration), equipment / vehicles / infrastructure; less access to technological knowledge; 2 1(d)(ii) max [1] strategy stated or described: max [1] description to match strategy: switch to low-carbon fuels; e.g. hydrogen use of hybrid vehicles / electric vehicles invest in renewable fuels; e.g. biofuel / bioethanol use of electric vehicles; reduces combustion of carbon-based fuel; reduces carbon dioxide emissions; grow food locally; no need for food to be transported; 2 Question Answer Marks 1(e)(i) benefits: improved crop yield / quality; as less competition from weeds; less herbicides needed; as weeds are quickly killed; easier management for farmer e.g. no selective / special herbicide required; limitations: encourages increased used of herbicides; leads to run-off; superweeds / weeds resistant to herbicide; loss of biodiversity as fewer weeds survive / reduces food or shelter for animals; contamination / cross pollination, between non-GM plants; GM seed is more expensive; farmers can’t save GM seed, need to purchase again following year; 4 1(e)(ii) any two from: light surfaces reflect more heat than dark surfaces; greater albedo means more of the incoming solar radiation is reflected back into space; ORA less incoming solar radiation is absorbed reduces (Earth’s absorbed) heat (energy); temperature of planet decreases; 2

This question in 8291/22 May/June 2023

3 Fig. 3.1 shows a leatherback turtle. Fig. 3.1 (a) Fig. 3.2 shows the location of three populations of leatherback turtles. Key population Atlantic Eastern Pacific N Indian Tropic of Cancer Equator Tropic of Capricorn Fig. 3.2 Use Fig. 3.2 to describe the location of the population of Eastern Pacific leatherback turtles. … … … … [2] (b) Fig. 3.3 shows the mean number of turtle nests for two populations of leatherback turtles. Key population Eastern Pacific Northwest Atlantic past three turtle generations ago present measured in 2010 future predicted for year 2040 200 000 180 000 160 000 140 000 120 000 mean annual 100 000 number of nests 80 000 60 000 40 000 20 000 0 past present future time Fig. 3.3 Use Fig. 3.3 to compare the two populations of leatherback turtles. … … … … [2] (c) Climate change is a major threat to leatherback turtles. Higher sand temperature during egg incubation leads to a higher number of female turtles. (i) Explain why higher sand temperature can be a result of climate change. … … … … [2] (ii) Suggest the impact higher sand temperature has on the population of turtles. Give reasons for your answer. impact … reasons … … … [2] (iii) Suggest one other impact of climate change that could decrease the population of turtles. Give a reason for your answer. … … … … [2] (iv) Fig. 3.4 shows a turtle caught in a fishing net. Fig. 3.4 One conservation strategy for protecting turtles is reducing the accidental catch of turtles in fishing nets. Suggest how the accidental catch of turtles in fishing nets can be prevented. … … [1] (d) Captive breeding and release is another method of conserving the population of turtles. Outline the benefits and limitations of captive breeding and release. benefits … … … … limitations … … … … [4] [Total: 15]

15 marks

Mark scheme: 3(a) any two from: west coast of South America; west coast of Mexico; west coast of Central America; south tropic of Cancer; north/ south tropic of Capricorn; east Pacific Ocean; north and south of equator; 2 3(b) any two comparisons from: NW Atlantic population increasing AND E Pacific decreasing overall; past-present: NW Atlantic gradual increase AND E Pacific (gradual) decrease; present-future: sharp increase from present to future for NW Atlantic AND E Pacific (gradual) decrease; comparison of trend with both populations from past / present / future; 2 3(c)(i) any two from: more, greenhouse gases / carbon dioxide / methane in atmosphere; which absorb infrared radiation; increased (enhanced) greenhouse effect / global warming; 2 3(c)(ii) impact: (population decrease or increase) with any two valid reasons: greater number of females : males in the population; limited number of (suitable males) mates; higher temperatures may damage eggs; one male can mate with many females; 2 Question Answer Marks 3(c)(iii) any one impact and one reason: rising sea level / extreme weather; wash eggs away; habitat loss; loss of food sources; more invasive species; greater competition / predation; possible migration; ocean acidification; too acidic loss of food source of turtles; AVP; 2 3(c)(iv) any one from: legislation; use line fishing instead of nets; no fishing in areas where turtles live; education / awareness of dangers of trapping turtles in nets; 1 3(d) max [3] benefits from: no predation; diseases / illnesses can be treated; prior selection of mates; allows research of species; max [3] limitations from: expensive; difficult to support a large breeding programme; behaviour / breeding / eating pattern, of captive animals may be affected; conditions may never be suitable to release animals; eggs have to be harvested from the wild; AVP; 4

This question in 8291/22 May/June 2023

1 Plants use chlorophyll to capture light energy for photosynthesis. (a) State the word equation for photosynthesis. … [2] (b) Chemists have developed a chemical that can be added to the roots of plants to improve the efficiency of photosynthesis. In laboratory studies, the chemical increased crop yield by 20%. Suggest why increasing crop yield can improve global food security. … … … … [2] (c) Maize is a food crop. Table 1.1 shows data for world maize yield in tonnes per hectare for two years. Table 1.1 yield year / tonnes per ha 1961 1.94 2018 5.92 Calculate the percentage increase in world maize yield from 1961 to 2018. … % [2] (d) Globally, 1.3 billion tonnes of food are wasted each year. 40% of all foods require refrigeration (cold temperatures) to maintain freshness. (i) Suggest why countries with low‑income economies are less likely to use refrigeration. … … … … [2] (ii) It is estimated that 15% of fossil fuel energy is used in the global transport of refrigerated food. Describe one strategy to reduce the use of fossil fuels in transporting food. … … … … [2] (e) Genetically modified (GM) crops can help improve food security. (i) ‘Roundup Ready’ soya is a GM crop grown in North and South America. This GM crop allows farmers to spray soya plants with herbicide. The GM crop is not harmed by herbicides. Suggest the benefits and limitations of using herbicide‑resistant GM crops, such as ‘Roundup Ready’ soya. benefits … … … limitations … … … [4] (ii) GM crops are being developed to have lighter and brighter coloured leaves than other crops. The lighter and brighter leaves increase the overall albedo of the plant. Explain how increased albedo can help to counteract climate change. … … … … [2] [Total: 16]

16 marks

Mark scheme: 1(a) reactants: carbon dioxide + water; products: glucose + oxygen; 2 1(b) any two from: provides enough food to feed the current / increasing population; more food can be grown in same area of land / intensification of food production; enables, stockpiling of food / surplus food; enables (improved) distribution of food; 2 1(c) 5.92  1.94 or 3.98; 205; 2 1(d)(i) any two from: lack of money; limited access to energy / electricity / energy insecure; lack of (refrigeration), equipment / vehicles / infrastructure; less access to technological knowledge; 2 1(d)(ii) max [1] strategy stated or described: max [1] description to match strategy: switch to low-carbon fuels; e.g. hydrogen use of hybrid vehicles / electric vehicles invest in renewable fuels; e.g. biofuel / bioethanol use of electric vehicles; reduces combustion of carbon-based fuel; reduces carbon dioxide emissions; grow food locally; no need for food to be transported; 2 Question Answer Marks 1(e)(i) benefits: improved crop yield / quality; as less competition from weeds; less herbicides needed; as weeds are quickly killed; easier management for farmer e.g. no selective / special herbicide required; limitations: encourages increased used of herbicides; leads to run-off; superweeds / weeds resistant to herbicide; loss of biodiversity as fewer weeds survive / reduces food or shelter for animals; contamination / cross pollination, between non-GM plants; GM seed is more expensive; farmers can’t save GM seed, need to purchase again following year; 4 1(e)(ii) any two from: light surfaces reflect more heat than dark surfaces; greater albedo means more of the incoming solar radiation is reflected back into space; ORA less incoming solar radiation is absorbed reduces (Earth’s absorbed) heat (energy); temperature of planet decreases; 2

This question in 8291/23 May/June 2023

3 Fig. 3.1 shows a leatherback turtle. Fig. 3.1 (a) Fig. 3.2 shows the location of three populations of leatherback turtles. Key population Atlantic Eastern Pacific N Indian Tropic of Cancer Equator Tropic of Capricorn Fig. 3.2 Use Fig. 3.2 to describe the location of the population of Eastern Pacific leatherback turtles. … … … … [2] (b) Fig. 3.3 shows the mean number of turtle nests for two populations of leatherback turtles. Key population Eastern Pacific Northwest Atlantic past three turtle generations ago present measured in 2010 future predicted for year 2040 200 000 180 000 160 000 140 000 120 000 mean annual 100 000 number of nests 80 000 60 000 40 000 20 000 0 past present future time Fig. 3.3 Use Fig. 3.3 to compare the two populations of leatherback turtles. … … … … [2] (c) Climate change is a major threat to leatherback turtles. Higher sand temperature during egg incubation leads to a higher number of female turtles. (i) Explain why higher sand temperature can be a result of climate change. … … … … [2] (ii) Suggest the impact higher sand temperature has on the population of turtles. Give reasons for your answer. impact … reasons … … … [2] (iii) Suggest one other impact of climate change that could decrease the population of turtles. Give a reason for your answer. … … … … [2] (iv) Fig. 3.4 shows a turtle caught in a fishing net. Fig. 3.4 One conservation strategy for protecting turtles is reducing the accidental catch of turtles in fishing nets. Suggest how the accidental catch of turtles in fishing nets can be prevented. … … [1] (d) Captive breeding and release is another method of conserving the population of turtles. Outline the benefits and limitations of captive breeding and release. benefits … … … … limitations … … … … [4] [Total: 15]

15 marks

Mark scheme: 3(a) any two from: west coast of South America; west coast of Mexico; west coast of Central America; south tropic of Cancer; north/ south tropic of Capricorn; east Pacific Ocean; north and south of equator; 2 3(b) any two comparisons from: NW Atlantic population increasing AND E Pacific decreasing overall; past-present: NW Atlantic gradual increase AND E Pacific (gradual) decrease; present-future: sharp increase from present to future for NW Atlantic AND E Pacific (gradual) decrease; comparison of trend with both populations from past / present / future; 2 3(c)(i) any two from: more, greenhouse gases / carbon dioxide / methane in atmosphere; which absorb infrared radiation; increased (enhanced) greenhouse effect / global warming; 2 3(c)(ii) impact: (population decrease or increase) with any two valid reasons: greater number of females : males in the population; limited number of (suitable males) mates; higher temperatures may damage eggs; one male can mate with many females; 2 Question Answer Marks 3(c)(iii) any one impact and one reason: rising sea level / extreme weather; wash eggs away; habitat loss; loss of food sources; more invasive species; greater competition / predation; possible migration; ocean acidification; too acidic loss of food source of turtles; AVP; 2 3(c)(iv) any one from: legislation; use line fishing instead of nets; no fishing in areas where turtles live; education / awareness of dangers of trapping turtles in nets; 1 3(d) max [3] benefits from: no predation; diseases / illnesses can be treated; prior selection of mates; allows research of species; max [3] limitations from: expensive; difficult to support a large breeding programme; behaviour / breeding / eating pattern, of captive animals may be affected; conditions may never be suitable to release animals; eggs have to be harvested from the wild; AVP; 4

This question in 8291/23 May/June 2023

1 Carbon capture and storage are strategies for managing climate change. Some companies are developing strategies to use captured carbon instead of storing the captured carbon. (a) Suggest the disadvantages of storing captured carbon rather than using captured carbon. … … … … … … [3] (b) In 2018, a company developed a unit for using carbon dioxide emitted from industry. The units are called ‘CO2ntainers’. Industrial waste products are reacted in a CO2ntainer with captured carbon dioxide at the location where the carbon dioxide is emitted. (i) Each CO2ntainer can treat a maximum of 12 000 tonnes of industrial waste per year. Four CO2ntainers are used at a factory. Calculate the maximum mass of industrial waste the four CO2ntainers can treat in five years. mass = … tonnes [2] (ii) Calcium carbonate and magnesium carbonate are produced by the CO2ntainers. Fig. 1.1 shows calcium carbonate and magnesium carbonate which are used in the construction industry. Fig. 1.1 Suggest how the CO2ntainer process reduces negative impacts on the environment. … … … … … … … … [4] (iii) The CO2ntainers use a process called carbonation. This process also occurs naturally. Organisms with shells absorb carbon dioxide from sea water and produce calcium carbonate for their shells. Suggest how this carbon dioxide is naturally stored for millions of years. … … … … … … [3] (c) Carbon dioxide is a limiting factor in the process of photosynthesis. State two other limiting factors in the process of photosynthesis. 1 … 2 … [2] [Total: 14]

14 marks

Mark scheme: Question Answer Marks 1(a) any three from: 3 cost of carbon storage / (storing the carbon) may be expensive; not enough storage facilities; technology for storing carbon is new / developing; stored carbon might leak; 1(b)(i) 4  12 000 (48 000) or5  12 000 (60 000); 2 240 000; 1(b)(ii) any four from: 4 reduces waste / reduces landfill usage; reduces need to quarry or mine; process is sustainable; reduces consumption of energy; permanently captures carbon dioxide; reduces (enhanced) greenhouse effect / greenhouse gas emission / global warming; (industrial) product has a low carbon footprint; reduces cost of raw materials in producing calcium / magnesium carbonate; 1(b)(iii) any three from: 3 (shelled) organisms die / build-up on the sea bed; (shelled organisms) covered in sediment / forms layers (of dead organisms / sediment); compaction / pressurised / cementation; form fossil fuels; 1(c) water / H2O; 2 (sun)light;

This question in 8291/21 Oct/Nov 2024

4 (a) Fig. 4.1 shows the distribution of hot desert biomes. Key hot desert biome Tropic of Cancer Equator Tropic of Capricorn Fig. 4.1 (i) Describe the distribution of hot desert biomes. … … … … … … [3] (ii) Draw an X on the map in Fig. 4.1 to indicate the location of a cold desert. [1] (b) Fig. 4.2 shows climate data for a hot desert biome. Content removed due to copyright restrictions. Fig. 4.2 (i) Complete Fig. 4.2 by drawing a line between data points for the temperature data. [1] (ii) Calculate the range for precipitation in the desert biome in Fig. 4.2. … mm [1] (iii) A desert biome receives 300 mm of precipitation a year. A rainforest biome receives 2000 mm of precipitation a year. Calculate the simplest whole number ratio for precipitation in the desert biome compared to the rainforest biome. … : … [1] (iv) Circle all the types of vegetation associated with a hot desert biome. cactus grass lichen moss vine [1]

8 marks

Mark scheme: 4(a)(i) any three from: 3 north and south of the Equator / between 15 and 35; mostly north of Equator; west side or west coast of land masses; named desert / country / continent e.g. Africa / Australia / North America / Middle East / Asia; 4(a)(ii) X drawn in Antarctica / Arctic / Greenland; 1 4(b)(i) line drawn between points; 1 4(b)(ii) 49; 1 4(b)(iii) 3 : 20 1 4(b)(iv) cactus and grass circled; 1 4(c)(i) F frequent and 1 O occasional and R rare; 4(c)(ii) 5 correct [2] 2 3–4 correct [1];; plant ACFOR species scale U C V R W F Y C Z F 4(c)(iii) any two from: 2 estimate / qualitative; biased / subjective; tendency for overestimate for conspicuous or flowering plants / underestimate for inconspicuous plants; 4(d)(i) 25, 9 plotted; 1 4(d)(ii) current number of bird species (at every location) is less than historic number; 1 4(d)(iii) very low chance / probability (of a bird species colonising a new location within the desert biome); 1

This question in 8291/21 Oct/Nov 2024

4 (a) Fig. 4.1 shows areas of tundra biome. Key tundra biome Tropic of Cancer Equator Tropic of Capricorn Fig. 4.1 Describe the distribution of tundra biome shown on Fig. 4.1. … … … … … … [3] (b) Fig. 4.2 shows climate data for a tundra biome. Key precipitation / mm temperature / °C 50 20 40 10 30 0 precipitation temperature / mm / °C 20 –10 10 –20 0 –30 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month Fig. 4.2 (i) Complete Fig. 4.2 by drawing a line between data points for the temperature data. [1] (ii) Calculate the range in precipitation for the tundra biome in Fig. 4.2. … mm [1] (iii) A tundra biome receives 250 mm of precipitation a year. A rainforest biome receives 2000 mm of precipitation a year. Calculate the simplest whole number ratio for precipitation in the tundra biome compared to the rainforest biome. … : … [1] (iv) Circle all the types of vegetation associated with a tundra biome. cactus fern lichen moss palm tree vine [1] (v) Suggest why crops are not grown in tundra biomes. … … … … … … … … [4]

11 marks

Mark scheme: 4(a) north of Tropic of Cancer / northern hemisphere; 3 Arctic circle; named location e.g. Arctic, Siberia / northern Russia, northern North America, northern Europe, northern Asia, Alaska, northern Canada, Greenland ;; 4(b)(i) line drawn between points; 1 4(b)(ii) 31; 1 4(b)(iii) 1 : 8; 1 4(b)(iv) lichen and moss; 1 4(b)(v) any four from: 4 presence of permafrost / frozen ground; thin layer of soil; cold temperatures; slow rate of photosynthesis; short growing season; limited water supply or rainfall; limited hours of sunlight / windy; 4(c)(i) divide area into grids / coordinates; 2 using a random number generator (for a grid reference / coordinates); 4(c)(ii) 5 sample positions shown with x; 2 (5) sample positions are equal distances apart and cover at least half of the line; 4(c)(iii) any three from: 3 only one location selected / not representative; only one day sampled / anomalous results not identified / data sample too small; 5 quadrats are not representative of the whole biome; no repeat of investigation; no mean determined; no information recorded on climatic conditions or weather; 4(d)(i) 16; 4 U = (0.125)2 = 0.015 V = (0.565)2 = 0.316 W = (0.0625)2 = 0.0039 Y = (0.1875)2 = 0.035 Z = (0.0625)2 = 0.0039 ; 0.374; 0.6(2538); 4(d)(ii) rainforest value will be higher and as more diverse / more plant species; 1

This question in 8291/22 Oct/Nov 2024

1 Carbon capture and storage are strategies for managing climate change. Some companies are developing strategies to use captured carbon instead of storing the captured carbon. (a) Suggest the disadvantages of storing captured carbon rather than using captured carbon. … … … … … … [3] (b) In 2018, a company developed a unit for using carbon dioxide emitted from industry. The units are called ‘CO2ntainers’. Industrial waste products are reacted in a CO2ntainer with captured carbon dioxide at the location where the carbon dioxide is emitted. (i) Each CO2ntainer can treat a maximum of 12 000 tonnes of industrial waste per year. Four CO2ntainers are used at a factory. Calculate the maximum mass of industrial waste the four CO2ntainers can treat in five years. mass = … tonnes [2] (ii) Calcium carbonate and magnesium carbonate are produced by the CO2ntainers. Fig. 1.1 shows calcium carbonate and magnesium carbonate which are used in the construction industry. Fig. 1.1 Suggest how the CO2ntainer process reduces negative impacts on the environment. … … … … … … … … [4] (iii) The CO2ntainers use a process called carbonation. This process also occurs naturally. Organisms with shells absorb carbon dioxide from sea water and produce calcium carbonate for their shells. Suggest how this carbon dioxide is naturally stored for millions of years. … … … … … … [3] (c) Carbon dioxide is a limiting factor in the process of photosynthesis. State two other limiting factors in the process of photosynthesis. 1 … 2 … [2] [Total: 14]

14 marks

Mark scheme: Question Answer Marks 1(a) any three from: 3 cost of carbon storage / (storing the carbon) may be expensive; not enough storage facilities; technology for storing carbon is new / developing; stored carbon might leak; 1(b)(i) 4  12 000 (48 000) or5  12 000 (60 000); 2 240 000; 1(b)(ii) any four from: 4 reduces waste / reduces landfill usage; reduces need to quarry or mine; process is sustainable; reduces consumption of energy; permanently captures carbon dioxide; reduces (enhanced) greenhouse effect / greenhouse gas emission / global warming; (industrial) product has a low carbon footprint; reduces cost of raw materials in producing calcium / magnesium carbonate; 1(b)(iii) any three from: 3 (shelled) organisms die / build-up on the sea bed; (shelled organisms) covered in sediment / forms layers (of dead organisms / sediment); compaction / pressurised / cementation; form fossil fuels; 1(c) water / H2O; 2 (sun)light;

This question in 8291/23 Oct/Nov 2024

4 (a) Fig. 4.1 shows the distribution of hot desert biomes. Key hot desert biome Tropic of Cancer Equator Tropic of Capricorn Fig. 4.1 (i) Describe the distribution of hot desert biomes. … … … … … … [3] (ii) Draw an X on the map in Fig. 4.1 to indicate the location of a cold desert. [1] (b) Fig. 4.2 shows climate data for a hot desert biome. Content removed due to copyright restrictions. Fig. 4.2 (i) Complete Fig. 4.2 by drawing a line between data points for the temperature data. [1] (ii) Calculate the range for precipitation in the desert biome in Fig. 4.2. … mm [1] (iii) A desert biome receives 300 mm of precipitation a year. A rainforest biome receives 2000 mm of precipitation a year. Calculate the simplest whole number ratio for precipitation in the desert biome compared to the rainforest biome. … : … [1] (iv) Circle all the types of vegetation associated with a hot desert biome. cactus grass lichen moss vine [1]

8 marks

Mark scheme: 4(a)(i) any three from: 3 north and south of the Equator / between 15 and 35; mostly north of Equator; west side or west coast of land masses; named desert / country / continent e.g. Africa / Australia / North America / Middle East / Asia; 4(a)(ii) X drawn in Antarctica / Arctic / Greenland; 1 4(b)(i) line drawn between points; 1 4(b)(ii) 49; 1 4(b)(iii) 3 : 20 1 4(b)(iv) cactus and grass circled; 1 4(c)(i) F frequent and 1 O occasional and R rare; 4(c)(ii) 5 correct [2] 2 3–4 correct [1];; plant ACFOR species scale U C V R W F Y C Z F 4(c)(iii) any two from: 2 estimate / qualitative; biased / subjective; tendency for overestimate for conspicuous or flowering plants / underestimate for inconspicuous plants; 4(d)(i) 25, 9 plotted; 1 4(d)(ii) current number of bird species (at every location) is less than historic number; 1 4(d)(iii) very low chance / probability (of a bird species colonising a new location within the desert biome); 1

This question in 8291/23 Oct/Nov 2024

2 Water turbidity measures the cloudiness of water. Turbidity is caused by undissolved solids in water. (a) A student uses a Secchi disc to measure the turbidity of water in four lakes, A, B, C and D. A Secchi disc is a white and black disc. The disc is suspended by a central cord. The cord has markings at 10 cm intervals. Fig. 2.1 shows a Secchi disc in water. water surface cord not to scale Fig. 2.1 The student: • lowers the Secchi disc into the water until the disc is completely invisible (cannot be seen). This depth is recorded as maximum depth. • raises the Secchi disc until the pattern on the disc is just visible. This depth is recorded as minimum depth. • calculates the mean of the maximum and minimum depths and records this as the Secchi depth. Table 2.1 shows the results. Table 2.1 maximum depth minimum depth Secchi depth lake / m / m / m A 3.40 0.20 1.80 B 2.90 0.50 C 5.75 0.30 3.03 D 4.85 0.45 2.65 (i) Calculate the Secchi depth for lake B. Secchi depth for lake B = … m [1] (ii) Suggest two reasons why it is not suitable to use a Secchi disc in some weather conditions. 1 … … 2 … … [2] (iii) The student repeats the investigation twice a week for three months. Explain why recording more than one set of maximum and minimum depths per lake is good sampling practice. … … … … [2] (b) Surface water contains phytoplankton. Phytoplankton are producers. (i) State the source of energy for phytoplankton. … [1] (ii) Explain why chlorophyll concentration is an indicator of primary production in surface water. … … … … [2] (c) The student investigates how Secchi depth relates to the concentration of surface water chlorophyll. Fig. 2.2 shows the results. 7 6 5 Secchi 4 depth / m 3 2 1 0 1 2 5 10 20 50 100 surface water chlorophyll concentration / arbitrary units Fig. 2.2 Write a suitable conclusion from the data in Fig. 2.2. … … … [1] (d) The ‘Secchi Disk Study’ is a crowd sourced investigation into global phytoplankton populations. In the study, people submit Secchi depths from oceans around the world and upload the data to a website. Fig. 2.3 shows the location of the crowd sourced sampling sites up to May 2022. Key sampling site N North Atlantic Ocean North Pacific Ocean South South Atlantic Pacific Indian Ocean Ocean Ocean Fig. 2.3 (i) Outline the benefits and limitations of obtaining scientific data by crowd sourcing. benefits … … … … limitations … … … … [4] (ii) Suggest how climate change could decrease phytoplankton populations. Give reasons for your answer. … … … … … … [3] (e) An electronic hand-held meter is used to measure turbidity at 70 locations along the length of a river. Fig. 2.4 shows the results. 60 50 40 turbidity / arbitrary 30 units 20 10 0 0 10 20 30 40 50 60 70 location number Fig. 2.4 (i) State which location has the greatest turbidity. location number = … [1] (ii) State the turbidity at location 41. turbidity = … arbitrary units [1] (f) Fig. 2.5 shows the relationship between fish activity and turbidity. 100 000 reduced growth 10 000 rates death fish abandon + cover 1000 + turbidity delayed hatching avoidance behaviour / arbitrary rates detected units + increased respiration + 100 + feeding stress reduced feeding rates fish start to + show signs increased coughing 10 of stress rates hours days weeks months time Fig. 2.5 The turbidity at location 7 remains at 48 arbitrary units for 3 weeks. Describe the impacts of this turbidity on fish activity. … … … … [2] [Total: 20]

20 marks

Mark scheme: 2(a)(i) 1.70; 1 2(a)(ii) any two from: 2 M1 wind / rain / floods / storms, stir up the water / disturb sediments / increase turbulence / change turbidity / reduces visibility (in water); M2 wind or storms, cord will not be vertical / cord will move / difficult to read; M3 wind or storms, cord or disc gets damaged / broken; M4 waves / not flat water / not calm water, difficult to read the cord / make depth variable; M5 (long period of) rain can, water levels that fluctuate / give variable depths; M6 lack of sunlight / cloudy / foggy / overcast / dull day, reduces visibility or difficult to see disc or cord; M7 high sunlight causes glare; M8 cold temperatures water could be frozen; M9 temperature changes particle distribution; M10 safety idea about going on water when bad weather; 2(a)(iii) any two from: 2 M1 identifies outliers / anomalous results excluded; M2 results can be compared; M3 mean found; M4 get representative data / increases sample size; 2(b)(i) Sun; 1 2(b)(ii) any two from: 2 M1 producers / phytoplankton/plants, contain chlorophyll; M2 as chlorophyll (concentration) increases (population of) producers increase / chlorophyll needed for photosynthesis; M3 higher chlorophyll (concentration) gives greater primary production / (primary) productivity; 2(c) any one from: 1 M1 as (Secchi) depth decreases chlorophyll or concentration increases / ORA; M2 higher the chlorophyll or higher concentration the lower the (Secchi) depth; 2(d)(i) total max four: 4 max three benefits: M1 cheap / costs less; M2 large quantity of data provided; M3 data can be collected from inaccessible areas / (scientist) don’t have to travel to all places; M4 representative data / global data; M5 quicker (for scientists) / saves (scientist) time; max three limitations: M6 big data / problem of analysing large quantity of data; M7 who owns the data rights; M8 amateurs / non-scientists / non-professionals, collecting data; M9 cannot verify or confirm data / no information about how data collected / subjective / potential for errors / misinterpretation / wrong information; M10 may only come from one areas / some areas not covered; M11 not everyone has access to website; 2(d)(ii) any three from: 3 M1 seas too warm / temperature of sea increases; M2 photosynthesis reduced; (rising temperatures cause): M3 change in salinity; M4 increased carbon dioxide concentrations; M5 ocean acidification / decrease in water pH; M6 change in ocean, circulation / currents; M7 phytoplankton cannot adjust to changed conditions; M8 increased risk of invasive species; M9 change in migration of organisms that consume phytoplankton; M10 more extreme weather / storms, increase turbidity (reducing photosynthesis); 2(e)(i) 4; 1 2(e)(ii) 29; 1 2(f) any two from: 2 M1 reduced growth (rates); M2 delayed or less, hatching (rates); M3 feeding stress / reduced feeding (rate) / reduced feeding success;

This question in 8291/21 May/June 2025

2 Fig. 2.1 shows a ghost swift moth. Moths are flying insects. 5 cm Fig. 2.1 (a) ‘Moth Night’ is an initiative for the public to record information about the moths they observe in one evening. (i) The public can either record the total number of moths they observe or the number of each species of moth they observe. Suggest why the public are given these two options. … … [1] (ii) The public report their observations using an online form. The online form asks for weather conditions during ‘Moth Night’. Suggest one benefit of including this data. … … [1] (b) A scientist uses the equipment shown in Fig. 2.2 to record data on moth populations. light source container Fig. 2.2 (i) Explain how the equipment is used to record data on moth populations. … … … … [2] (ii) Suggest why a damp sponge is put into the bottom of the equipment. … … [1] (iii) State two limitations of this method of recording data on moth populations. 1 … … 2 … … [2] (c) The scientist uses the equipment in (b) to record the number of ghost swift moths collected over a 50-year period. Fig. 2.3 shows the results. Content removed due to copyright restrictions. Fig. 2.3 (i) State the range for the number of moths collected. range = … [1] (ii) Use Fig. 2.3 to write two conclusions about the ghost swift moth population. 1 … … 2 … … [2] (d) Moths are pollinating insects. (i) Fig. 2.4 shows the effect of introducing pollinating insects (pollinators) to a field of fruit trees. 20 000 750 15 000 profit in 500 10 000 USD ($) / ha number of fruits per tree 250 5000 0 0 no yes no yes pollinators introduced pollinators introduced Fig. 2.4 Use Fig. 2.4 to explain how pollinators improve food security. … … … … … … [3] (ii) Fig. 2.5 shows the percentage of crops dependent on pollinators in a world region. Key percentage of crops dependent on pollinators > 50% 25 – 49% 10 – 24% N 0 – 9% no data Tropic of Cancer Equator Tropic of Capricorn 0 2000 km Fig. 2.5 Describe the distribution of crops dependent on pollinators. … … … … … [2] (e) Fig. 2.6 shows a food web that includes a moth. owl stoat chiffchaff bluetit moth spider vole ladybird aphid plant not to scale Fig. 2.6 Use Fig. 2.6 to write a food chain that includes a producer and has a total of four trophic levels. … [2] (f) Fig. 2.7 shows a pyramid of numbers for a food chain. Fig. 2.7 Explain why a pyramid of numbers does not need to be a pyramid shape. … … … … [2] [Total: 19]

19 marks

Mark scheme: 2(a)(i) any one from: 1 MP1 not everyone knows the species of moth; MP2 public are not experts in identifying moths; 2(a)(ii) so results across the country can be compared (for different weather conditions); 1 2(b)(i) MP1 light attracts moths; 2 MP2 fall into container; 2(b)(ii) to prevent dehydration (of moths) / for moths to drink; 1 2(b)(iii) any two from: 2 MP1 species other than moths are collected; MP2 only attracts moths active at night; MP3 uses electricity / energy (which is expensive); MP4 non-target species may eat moths; MP5 moths may get killed by flying too close to light; MP6 difficult to use in wet/windy conditions; 2(c)(i) 420; 1 2(c)(ii) any two from: 2 MP1 fluctuating population; MP2 overall decline from year 1 to year 50; MP3 population starts to recover after 32 years; MP4 difficult to determine if moth population declining, requires more data / time ; 2(d)(i) any three from: 3 MP1 increase crop yield / number of fruit on tree; MP2 increase profit; MP3 max two examples of how profit can be used to increase food security e.g. reinvest in seeds / new crops / machinery;; MP4 MP1 leads to lower food prices; 2(d)(ii) any two from: 2 MP1 25–49% / 10–24% are most frequent; MP2 most dependent crops are within the tropics; MP3 relevant quoted data e.g. North America is 10–24% ; 2(e) MP1 plant as first trophic level and four trophic levels total; 2 MP2 arrows pointing correctly; plant → moth → bluetit → owl 2(f) any two from: 2 MP1 shows the total number of individual organisms at each, food chain level / trophic level; MP2 does not take into account biomass of (organisms); MP3 top level may be parasites; MP4 small number of producers could support larger number of smaller consumers / ORA;

This question in 8291/23 May/June 2025

3 Fig. 3.1 shows an Arctic walrus resting on sea ice. Fig. 3.1 (a) Fig. 3.2 shows a food chain for an Arctic walrus. phytoplankton clams Arctic walrus polar bear Fig. 3.2 (i) State the term given to phytoplankton in this food chain. … [1] (ii) Identify a secondary consumer in this food chain. … [1] (iii) Explain what happens to energy in this food chain. … … … … … … … … … [5] (b) Walruses usually rest on sea ice between feeding. However, in the last 10 years, large numbers of walrus have been seen to travel up to 200 km to rest on land. (i) Suggest one reason for this change in behaviour. … … [1] (ii) Suggest two negative impacts on walruses due to this change in behaviour. 1 … … 2 … … [2] (c) Fig. 3.3 is a drawing of a satellite image from a project called ‘walrus from space’. Content removed due to copyright restrictions. Fig. 3.3 The project counts populations of walrus using more than 540 000 satellite images. Members of the public volunteer to help with the project. There are three stages to the project. stage 1: A satellite image of an area where walrus are expected is given to a volunteer. stage 2: The volunteer rejects any satellite image without a walrus. stage 3: The volunteer puts an electronic dot on every walrus in the satellite image. The dots are counted by a computer. (i) Suggest three limitations of this project to count walrus populations. 1 … … 2 … … 3 … … [3] (ii) Suggest two benefits of this project to count walrus populations. 1 … … 2 … … [2] (iii) State the name of this data collection method that uses data provided by members of the public. … [1] [Total: 16]

16 marks

Mark scheme: 3(a)(i) producer; 1 3(a)(ii) (Arctic) walrus 1 3(a)(iii) any five from: 5 M1 energy decreases (between trophic or feeding levels or from phytoplankton to polar bear); M2 amount transferred is approximately 10% (between trophic or feeding levels or from phytoplankton to polar bear); M3 between EACH trophic or feeding levels or from phytoplankton to polar bear, energy is lost from the food chain; reasons for decrease in energy: M4 not every part of organisms is eaten; M5 some parts of organisms are not digested; M6 some energy lost as, waste (products) / urine / faeces / excretion; M7 energy released as heat or thermal energy; M8 due to, digestion / respiration / metabolic processes / movement / reproduction / growth; 3(b)(i) any one from: 1 M1 reduction in sea ice / (sea) ice has melted; M2 travelling further to find food / reduction in food supply; 3(b)(ii) any two from: 2 M1 uses up energy reserves; M2 risk of disease in large groups; M3 increased risk of predation; M4 increased risk of coming into contact with humans; 3(c)(i) any three from: 3 M1 difficult to see or count walruses from space; M2 idea of walruses huddled together so difficult to see or count individuals; M3 walruses move around / walruses may be below water or hidden; M4 satellite imagery can’t be used when cloudy; M5 expense of satellite; M6 using, non-scientists / non-experts / amateurs; M7 requires people to make judgement / confused with other animals; M8 idea of big data with lots of satellite images to sort through / time consuming (to analyse data); 3(c)(ii) any two from: 2 M1 volunteers do not need to be paid; M2 partly automated / less time-consuming (than going to walruses); M3 do not need to go to where walruses are / doesn’t disturb walruses or environment; M4 can cover a large area / large amount of data; M5 raises awareness; 3(c)(iii) crowd sourcing; 1

This question in 8291/21 Oct/Nov 2025

2 Albatross are birds. Many of the 22 species of albatross are listed by the International Union for Conservation of Nature (IUCN) Red List. (a) Describe how the IUCN Red List helps conserve biodiversity. … … … … [2] (b) Albatrosses make mud nests on the ground to lay their eggs. Fig. 2.1 shows albatrosses on the mud nests. mud nest Fig. 2.1 Suggest two reasons why these mud nests are at risk from climate change. 1 … … 2 … … [2] (c) Fig. 2.2 shows a food web for albatrosses. gulls small fish albatross octopus squid phytoplankton shrimp large fish Fig. 2.2 Write a food chain for the albatross. Start the food chain with a producer and include a total of four trophic levels. … [2] (d) Mercury is a toxic metal. The concentration of mercury in organisms in the food web in Fig. 2.2 is investigated. For albatrosses, their feathers are analysed. For the other organisms in the food web, their flesh is analysed. (i) Suggest two reasons why only the feathers are analysed for albatrosses. 1 … … 2 … … [2] (ii) The mean level of mercury in the prey of the albatross was 0.0005 μg per g. Circle the predicted mean level of mercury in albatrosses. Explain your answer. 0.0001 μg per g 0.0005 μg per g 3.88 μg per g … … [2] (e) Albatrosses can travel over 1500 km a day to find food. Suggest how radio tracking is used to record the distances albatrosses travel to find food. … … … … [2] (f) Satellite images from space are used to determine albatross population near Antarctica. Fig. 2.3 shows a satellite image of some nesting albatrosses. Key albatross 0 3 m Fig. 2.3 (i) Record the number of albatrosses shown in Fig. 2.3 as a tally. number of albatrosses [1] (ii) Crowd sourcing is used to count the number of albatrosses on each satellite image. Describe what is meant by crowd sourcing. … … [1] (iii) Suggest the benefits and limitations of using satellite images to determine the population of albatrosses. benefits … … … … limitations … … … … [4] (g) Different species of albatross build nests in the same area. A scientist uses Simpson’s index of diversity to investigate the different species of albatross in an area. D = 1 – (∑(nN) 2) State what each of the letters represent in this formula. ∑ … n … N … [3] [Total: 21]

21 marks

Mark scheme: 2(a) any two from: 2 M1 identifies threat status of organisms or species; M2 monitors, organisms / ecosystems; M3 raises awareness; M4 aims to influence policies or laws in favour of biodiversity; 2(b) any two from: 2 M1 increased, rainfall / flooding / sea level rise, washes away nests; M2 increased, storms / wind / extreme weather, blows away nests; M3 increased temperature / lack of rainfall, dries out or cracks mud; M4 loss of land due to sea level rise so less available land to build nests; M5 this increases competition for available land; 2(c) M1 phytoplankton; 2 M2 total of four levels and with arrows in correct direction; phytoplankton → small fish → large fish → albatross 2(d)(i) M1 don’t need to kill the albatross; 2 M2 (albatross are) listed in (IUCN) Red List / idea of being endangered or threatened; 2(d)(ii) M1 3.88 g per g circled; 2 M2 biomagnification / concentration (of toxins) increases up a food chain; 2(e) M1 tag or (radio) tracker fitted to bird; 2 M2 (location transmitted which is) received by GPS; 2(f)(i) tally used with 34 shown; 1 2(f)(ii) using large numbers of people / general public, to obtain data; 1 2(f)(iii) total four from: 4 max three benefits: M1 large area can be sampled; M2 do not need to go to where albatrosses are / Antarctica is difficult to get to; M3 does not disturb albatrosses / does not disturb environment; M4 quick to sample / quick to take images; M5 birds are not counted twice (in static image); max three limitations: M6 idea of big data / time consuming (to count or analyse all images); M7 idea of albatross huddled together so difficult to see or count individual birds; M8 can’t be used when cloudy; M9 expense (of satellite); M10 cannot identify different species; 2(g) M1  sum of (total); 3 M2 n number of individuals of each species (present in the sample); M3 N total number of all individuals in all species (present in sample);

This question in 8291/22 Oct/Nov 2025

4 (a) Fig. 4.1 shows a map of drought risk. Content removed due to copyright restrictions. Fig. 4.1 (i) Describe the distribution of countries with high drought risk. … … … … … [3] (ii) A lack of drinking water is an impact of drought. This can cause deaths. State three other impacts of drought. 1 … 2 … 3 … [3] (b) Fig. 4.2 shows climate data from a weather station in the Northern Territory, Australia. Content removed due to copyright restrictions. Fig. 4.2 (i) State the highest mean temperature. … °C [1] (ii) State which three months had the greatest mean rainfall. … and … and … [1] (iii) Suggest why the rate of primary productivity decreases during June to August near the location of this weather station. Use Fig. 4.2 to support your answer. … … … … [2] (c) Some areas of the Northern Territory have a grassland biome. Describe the soil type in a grassland biome. … … … … [2] (d) Cane toads are an invasive species in the Northern Territory. Explain the impacts of invasive species on biodiversity. … … … … … … [3] [Total: 15]

15 marks

Mark scheme: 4(a)(i) any three from: 3 M1 most of Europe / Eastern Europe / Southern Europe; M2 South Asia / Southeast Asia; M3 (mostly) north of Tropic of Cancer / in the region of Tropic of Cancer; M4 some countries bordering Equator; M5 named country e.g. Moldova / Ukraine / Bangladesh / India / Serbia; 4(a)(ii) any three from: 3 M1 wild fires; M2 crop failure / reduced crop yield; M3 food insecurity / famine / food shortages; M4 water insecurity / poor sanitation / disease; M5 lower HEP production; 4(b)(i) 32; 1 4(b)(ii) Jan and Feb and Dec; 1 4(b)(iii) any two from: 2 M1 low(est) rainfall / rainfall less than 5 mm; M2 water needed for photosynthesis; M3 green plants convert carbon dioxide and water to glucose and oxygen; 4(c) any two from: 2 M1 thick or deep layer of humus / thick or deep layer of decaying plants or animals; M2 high nutrients / high fertility / are fertile / high organic content; M3 reference to, moisture content / porosity / pH / colour; 4(d) any three from: 3 M1 compete with native organisms (for resources); M2 disrupt food chains; M3 spread disease; M4 alter habitats; M5 (leads to) loss of biodiversity / extinction (of native species);

This question in 8291/22 Oct/Nov 2025

3 Fig. 3.1 shows an Arctic walrus resting on sea ice. Fig. 3.1 (a) Fig. 3.2 shows a food chain for an Arctic walrus. phytoplankton clams Arctic walrus polar bear Fig. 3.2 (i) State the term given to phytoplankton in this food chain. … [1] (ii) Identify a secondary consumer in this food chain. … [1] (iii) Explain what happens to energy in this food chain. … … … … … … … … … [5] (b) Walruses usually rest on sea ice between feeding. However, in the last 10 years, large numbers of walrus have been seen to travel up to 200 km to rest on land. (i) Suggest one reason for this change in behaviour. … … [1] (ii) Suggest two negative impacts on walruses due to this change in behaviour. 1 … … 2 … … [2] (c) Fig. 3.3 is a drawing of a satellite image from a project called ‘walrus from space’. Content removed due to copyright restrictions. Fig. 3.3 The project counts populations of walrus using more than 540 000 satellite images. Members of the public volunteer to help with the project. There are three stages to the project. stage 1: A satellite image of an area where walrus are expected is given to a volunteer. stage 2: The volunteer rejects any satellite image without a walrus. stage 3: The volunteer puts an electronic dot on every walrus in the satellite image. The dots are counted by a computer. (i) Suggest three limitations of this project to count walrus populations. 1 … … 2 … … 3 … … [3] (ii) Suggest two benefits of this project to count walrus populations. 1 … … 2 … … [2] (iii) State the name of this data collection method that uses data provided by members of the public. … [1] [Total: 16]

16 marks

Mark scheme: 3(a)(i) producer; 1 3(a)(ii) (Arctic) walrus 1 3(a)(iii) any five from: 5 M1 energy decreases (between trophic or feeding levels or from phytoplankton to polar bear); M2 amount transferred is approximately 10% (between trophic or feeding levels or from phytoplankton to polar bear); M3 between EACH trophic or feeding levels or from phytoplankton to polar bear, energy is lost from the food chain; reasons for decrease in energy: M4 not every part of organisms is eaten; M5 some parts of organisms are not digested; M6 some energy lost as, waste (products) / urine / faeces / excretion; M7 energy released as heat or thermal energy; M8 due to, digestion / respiration / metabolic processes / movement / reproduction / growth; 3(b)(i) any one from: 1 M1 reduction in sea ice / (sea) ice has melted; M2 travelling further to find food / reduction in food supply; 3(b)(ii) any two from: 2 M1 uses up energy reserves; M2 risk of disease in large groups; M3 increased risk of predation; M4 increased risk of coming into contact with humans; 3(c)(i) any three from: 3 M1 difficult to see or count walruses from space; M2 idea of walruses huddled together so difficult to see or count individuals; M3 walruses move around / walruses may be below water or hidden; M4 satellite imagery can’t be used when cloudy; M5 expense of satellite; M6 using, non-scientists / non-experts / amateurs; M7 requires people to make judgement / confused with other animals; M8 idea of big data with lots of satellite images to sort through / time consuming (to analyse data); 3(c)(ii) any two from: 2 M1 volunteers do not need to be paid; M2 partly automated / less time-consuming (than going to walruses); M3 do not need to go to where walruses are / doesn’t disturb walruses or environment; M4 can cover a large area / large amount of data; M5 raises awareness; 3(c)(iii) crowd sourcing; 1

This question in 8291/23 Oct/Nov 2025