Collection of environmental data — Paper 2 · A Level Environmental Management (AS only) 8291

4 In 2020, Ethiopia, a country in Africa, had 15% of its land covered by forest. Fifty years ago, 40% of Ethiopia was covered by forest. (a) (i) Suggest how the percentage forest cover for a country can be measured. … … [1] (ii) Explain how deforestation reduces biodiversity. … … … … [2] (b) A student used a questionnaire to ask some people in Ethiopia for their opinion on how forest cover has changed in their local area. Table 4.1 shows the results of the questionnaire. Table 4.1 percentage response rapidly gradually same as increasing no opinion decreasing decreasing before 50 30 10 7 3 (i) Write a suitable conclusion that summarises the main opinion on how forest cover has changed in Ethiopia. … … [1] (ii) Draw a pie chart of the data in Table 4.1. Complete the key. 0 Key … … … … … [3] (iii) Suggest one piece of additional information that is needed to ensure the data in Table 4.1 is reliable. … … [1] (c) In 2019, a major reforestation programme took place in Ethiopia. 350 million trees were planted over a 12-hour period in July. (i) Suggest one reason why not all of the 350 million trees planted will grow into mature trees. … … [1] (ii) Suggest one reason why other countries do not have a similar reforestation programme. … … [1] (iii) Explain how reforestation can improve water security in a region. … … … … … … [3] (iv) In the past, eucalyptus trees were used to reforest areas of Ethiopia. Eucalyptus trees are not native to Ethiopia. Suggest the negative impacts of planting non-native trees. … … … … … … [3] (v) Explain how reforestation can help manage climate change. … … … … … … … … [4] [Total: 20]

20 marks

Mark scheme: 4(a)(i) any one from: satellite; geospatial systems / geographical information systems / GIS; crowd sourcing / surveying; arial photographs / drones; 1 4(a)(ii) any two or developed from: habitat lost / habitat fragmentation; reduces food / disrupts food chains or web / increase competition / reduces carrying capacity; increased predation / less protection from predators; disrupts ecological corridors; changes land use / primary forest replaced by secondary forest; causes migration (of species); soil erosion; loss of, soil fertility / soil structure; 2 4(b)(i) forest cover is decreasing; 1 4(b)(ii) sectors in rank order largest first beginning at noon and proceeding clockwise; correct plotting  1%; sectors match key; 3 4(b)(iii) any one from: sample size; we need information on the method of collection; demographic / information about who has been sampled; 1 Question Answer Marks 4(c)(i) any one from: lack of water; disease; soil infertile / lack of nutrients; natural disaster / wildfires; eaten by livestock or animals; competition or described; tree stolen / damaged by people; removed as part of forest management / trees cut down / trees harvested; 1 4(c)(ii) any one from: cost; other priorities / not seen as important; public or political opinion / lack of volunteers to plant them; lack of land / area already forested; 1 4(c)(iii) any two from: improved soil e.g. improved structure / roots bind soil / improved nutrients / improved fertility; reduces global warming / reduces global temperatures; decreases evaporation from soil; increases interception; increases infiltration decreases run-off. increases (evapo)transpiration / increased water evaporating from leaves; leads to, moisture condenses / increases cloud cover / more precipitation; any one from: soil can absorb more water / soil can hold more water / water can soak into soil; increases or recharge groundwater stores / recharges aquifers; 3 Question Answer Marks 4(c)(iv) any three from: could become invasive; out compete native trees / deplete nutrients / increased competition in food chain / competition described / disrupt food chain / loss of biodiversity; no natural predators / not (local) food source toxic / poisonous; diseases; 3 4(c)(v) any four or developed from: (growing trees are) carbon capture or sinks; (mature trees are) carbon stores; during photosynthesis; reduce carbon dioxide / CO2 (from atmosphere); carbon dioxide + water  glucose + oxygen OR 6CO2 + 6H2O  C6H12O6 + 6O2 ; 4

This question in 8291/21 May/June 2022

2 Fig. 2.1 shows the African clawed frog and tadpole. The frog is native to Africa. 1–5 cm 5–12 cm tadpole mature frog Fig. 2.1 The female African clawed frog typically lays between 500–2000 eggs at a time. Fertilised eggs hatch into tadpoles and the tadpoles change into frogs. (a) A researcher investigated the effect of artificial light on the African clawed frog. The researcher collected samples of fertilised eggs from five different female frogs, A, B, C, D and E. Artificial light was used on each sample for a different number of hours per day for 8 weeks. The number of adult frogs after 8 weeks was counted. The investigation was repeated with a different egg sample from the same five female frogs. The results are shown in Table 2.1. Table 2.1 artificial light number of adult frogs frog / hours per day investigation 1 investigation 2 mean A 0 205 307 256 B 4 198 3 198 C 8 200 250 225 D 16 105 111 108 E 24 83 89 86 (i) Calculate the range for the number of adult frogs from frog D. range = … [1] (ii) Plot a bar chart of the mean number of adult frogs (y‑axis) against the hours of artificial light per day. [4] (iii) Suggest a reason why the result for frog B in investigation 2 was not included in the mean. … … [1] (iv) Use the data in Table 2.1 to write a suitable conclusion for the investigation. … … [1] (v) Describe one limitation of the method of egg sampling used in this investigation. … … [1] (b) Fig. 2.2 shows a 20 m tape fixed along the edge of a pond. pond 20 m tape Fig. 2.2 Describe a suitable quadrat method for collecting data on the population of the African clawed frog along the 20 m tape using an open quadrat. … … … … … … … … [4] (c) Water was collected from the pond at six sample sites and the salinity measured at each site. The salinity is recorded as the salt concentration in parts per million (ppm). Fig. 2.3 shows the location of the six sample sites. Key sample site pond 20 m tape Fig. 2.3 (i) Suggest one limitation of the location of the sample sites. … … [1] (ii) Table 2.2 shows the salt concentrations from the six sample sites at the pond. Table 2.2 salt concentration sample site / ppm 1 252 2 300 3 321 4 257 5 281 6 314 Calculate the mean salt concentration for the six sample sites. Give your answer to the nearest whole number. mean salt concentration = … ppm [1] (d) Suggest reasons why the African clawed frog has become an invasive species in some locations. … … … … [2] (e) Salinity is one abiotic component of an ecosystem. State one other abiotic component. … [1] (f) A food chain for the African clawed frog is shown. grass grasshopper African clawed frog snake (i) Identify the tertiary consumer in this food chain. … [1] (ii) Identify which trophic level will be affected the most by biomagnification. … [1] (iii) Suggest the short‑term effect on the population of grasshoppers if the number of African clawed frogs increases. Give a reason for your answer. effect … reason … … [1] [Total: 20]

20 marks

Mark scheme: 2(a)(i) 6; 1 2(a)(ii) sensible linear scale and data occupying over half the grid; axes labels AND unit; e.g. y-axis label:( mean) number of frogs AND x-axis: artificial light / hours per day 5 correct plotted points  half small square; bars of equal width that are not touching; 4 2(a)(iii) anomalous result / outlier; 1 Question Answer Marks 2(a)(iv) any one from: the more artificial light per day the fewer the number of adult frogs; tadpoles are less likely to mature into adult frogs with artificial light; 1 2(a)(v) any one from: do not know the original number of eggs; each female may lay different numbers of eggs; small sample of frogs / only five frogs sampled; 1 2(b) stated size of quadrat e.g. 1 m  1 m quadrat; stated sampling distances e.g. every 5 metres / systematic e.g. every metre OR distances selected at random; count number of frogs (in the quadrat); repeat AND take an average; 4 2(c)(i) not representative / all in one place; 1 2(c)(ii) 288; 1 2(d) any two from: can survive in conditions other frogs cannot; outcompetes other frogs; produces a lot of eggs; accidental introduction (by humans); no predators; 2 2(e) any one from: temperature; humidity; water; oxygen; light; pH; 1 2(f)(i) snake; 1 2(f)(ii) 4th; 1 Question Answer Marks 2(f)(iii) decrease population AND, more predators / more are eaten; 1

This question in 8291/22 May/June 2023

2 Fig. 2.1 shows the African clawed frog and tadpole. The frog is native to Africa. 1–5 cm 5–12 cm tadpole mature frog Fig. 2.1 The female African clawed frog typically lays between 500–2000 eggs at a time. Fertilised eggs hatch into tadpoles and the tadpoles change into frogs. (a) A researcher investigated the effect of artificial light on the African clawed frog. The researcher collected samples of fertilised eggs from five different female frogs, A, B, C, D and E. Artificial light was used on each sample for a different number of hours per day for 8 weeks. The number of adult frogs after 8 weeks was counted. The investigation was repeated with a different egg sample from the same five female frogs. The results are shown in Table 2.1. Table 2.1 artificial light number of adult frogs frog / hours per day investigation 1 investigation 2 mean A 0 205 307 256 B 4 198 3 198 C 8 200 250 225 D 16 105 111 108 E 24 83 89 86 (i) Calculate the range for the number of adult frogs from frog D. range = … [1] (ii) Plot a bar chart of the mean number of adult frogs (y‑axis) against the hours of artificial light per day. [4] (iii) Suggest a reason why the result for frog B in investigation 2 was not included in the mean. … … [1] (iv) Use the data in Table 2.1 to write a suitable conclusion for the investigation. … … [1] (v) Describe one limitation of the method of egg sampling used in this investigation. … … [1] (b) Fig. 2.2 shows a 20 m tape fixed along the edge of a pond. pond 20 m tape Fig. 2.2 Describe a suitable quadrat method for collecting data on the population of the African clawed frog along the 20 m tape using an open quadrat. … … … … … … … … [4] (c) Water was collected from the pond at six sample sites and the salinity measured at each site. The salinity is recorded as the salt concentration in parts per million (ppm). Fig. 2.3 shows the location of the six sample sites. Key sample site pond 20 m tape Fig. 2.3 (i) Suggest one limitation of the location of the sample sites. … … [1] (ii) Table 2.2 shows the salt concentrations from the six sample sites at the pond. Table 2.2 salt concentration sample site / ppm 1 252 2 300 3 321 4 257 5 281 6 314 Calculate the mean salt concentration for the six sample sites. Give your answer to the nearest whole number. mean salt concentration = … ppm [1] (d) Suggest reasons why the African clawed frog has become an invasive species in some locations. … … … … [2] (e) Salinity is one abiotic component of an ecosystem. State one other abiotic component. … [1] (f) A food chain for the African clawed frog is shown. grass grasshopper African clawed frog snake (i) Identify the tertiary consumer in this food chain. … [1] (ii) Identify which trophic level will be affected the most by biomagnification. … [1] (iii) Suggest the short‑term effect on the population of grasshoppers if the number of African clawed frogs increases. Give a reason for your answer. effect … reason … … [1] [Total: 20]

20 marks

Mark scheme: 2(a)(i) 6; 1 2(a)(ii) sensible linear scale and data occupying over half the grid; axes labels AND unit; e.g. y-axis label:( mean) number of frogs AND x-axis: artificial light / hours per day 5 correct plotted points  half small square; bars of equal width that are not touching; 4 2(a)(iii) anomalous result / outlier; 1 Question Answer Marks 2(a)(iv) any one from: the more artificial light per day the fewer the number of adult frogs; tadpoles are less likely to mature into adult frogs with artificial light; 1 2(a)(v) any one from: do not know the original number of eggs; each female may lay different numbers of eggs; small sample of frogs / only five frogs sampled; 1 2(b) stated size of quadrat e.g. 1 m  1 m quadrat; stated sampling distances e.g. every 5 metres / systematic e.g. every metre OR distances selected at random; count number of frogs (in the quadrat); repeat AND take an average; 4 2(c)(i) not representative / all in one place; 1 2(c)(ii) 288; 1 2(d) any two from: can survive in conditions other frogs cannot; outcompetes other frogs; produces a lot of eggs; accidental introduction (by humans); no predators; 2 2(e) any one from: temperature; humidity; water; oxygen; light; pH; 1 2(f)(i) snake; 1 2(f)(ii) 4th; 1 Question Answer Marks 2(f)(iii) decrease population AND, more predators / more are eaten; 1

This question in 8291/23 May/June 2023

2 (a) A student investigates the concentration of nitrate ions in a lake. The student makes the following hypothesis: ‘The concentration of nitrate ions in lake water increases on hotter days.’ The student collects a sample of lake water on each of five days and records the air temperature on each day. The student measures the concentration of nitrate ions in each water sample. (i) State the independent variable in this investigation. … [1] (ii) State one variable the student should control in this investigation. … [1] (iii) Explain the benefit of repeating an investigation. … … … … [2] (b) Table 2.1 shows the student’s results. Table 2.1 air concentration of nitrate ions water sample temperature in mg / dm3 / °C 1 2.7 21 2 3.1 19 3 4.2 23 4 3.3 32 5 2.5 35 (i) Calculate the mean concentration of nitrate ions shown in Table 2.1. Give your answer to one decimal place. mean = … mg / dm3 [2] (ii) Calculate the air temperature range shown in Table 2.1. range = … °C [1] (iii) The student’s hypothesis for this investigation was: ‘The concentration of nitrate ions in lake water increases on hotter days.’ Interpret the data in Table 2.1 to conclude whether the student’s hypothesis is correct. Support your conclusion with evidence from Table 2.1. … … [1] (iv) Describe a systematic sampling strategy the student could use to collect the five water samples. … … [1] (v) One standard for drinking water in the United States is a maximum concentration of nitrate ions of 10 mg / dm3. The lake water has concentrations of nitrate ions lower than 10 mg / dm3. Suggest why it is not possible to conclude that the lake water is suitable to provide drinking water from only the results in Table 2.1. … … [1] (c) Water in drinking wells is at risk of contamination from nitrate ions. The map in Fig. 2.1 shows the location of drinking-water wells in the state of Minnesota in the United States and the concentration of nitrate ions in these wells. Key international border nitrate ion concentration in mg / dm3 state capital 3.0–10.0 >10.0 N Canada Lake North Superior Dakota Wisconsin Iowa Fig. 2.1 (i) Describe the distribution of nitrate ion concentration in drinking-water wells shown in Fig. 2.1. … … … … … … [3] (ii) State the process by which nitrate ions enter groundwater from soil. … [1] (d) Artesian wells can supply drinking water. State two other supply methods for drinking water. 1 … 2 … [2] (e) Polluted drinking water leads to water insecurity. Water insecurity leads to increased poverty. (i) Suggest reasons why water insecurity leads to poverty. … … … … [2] (ii) Explain how water insecurity can lead to lower levels of food production. … … … … [2] [Total: 20]

20 marks

Mark scheme: 2(a)(i) (air) temperature; 1 2(a)(ii) any one from: 1 volume / amount of water; collect water, in same way / at same depth; time of day / time of collection; location e.g. side of lake / position of sampling; 2(a)(iii) any two from: 2 results can be compared; anomalous results exclude / identifies anomalous results or outliers / identify mistakes; average/mean found; averaging/identifying anomalies increases accuracy; averaging reduces effect of random errors / reduces margin of error; confirm results / proves or disproves results; 2(b)(i) answer to one decimal place: 3.2; 2 unrounded answer: 3.16; 2(b)(ii) 16; 1 2(b)(iii) no; 1 AND any one from: valid evidence e.g. highest temperature and lowest concentration or correctly quoted data; no correlation (between air temperature and concentration of nitrate ions); 2(b)(iv) systematic sampling described e.g. every nth distance across lake selected; 1 2(b)(v) any one from: 1 data only gives information on nitrate; only five samples / not representative; may contain other pollutants / named pollutant; 2(c)(i) any three from: 3 nitrate concentrations (in wells) greatest in centre of state / towards middle / increases close to the state capital; cluster in southwest corner > 10.0 (mg /L ); between 3.0–10.0 (mg / L) in south east corner / between Wisconsin and Iowa; low concentrations along border with Lake Superior / in North / border with Canada; low concentrations around the state capital; 2(c)(ii) leaching; 1 2(d) any two from: 2 piped / from taps; aquifer; borehole; gravity-fed; reservoirs / dams; 2(e)(i) any two from: 2 people spend hours collecting water; cannot work / cannot earn money; cannot attend school / get an education; people drink contaminated water; people become ill (dehydrated / water-borne disease) so cannot work; less crops grown so less income for farmers / higher prices so cannot afford; 2(e)(ii) any two from: 2 limited or no irrigation; unreliable water supply / water available at wrong time for crop growth; water needed for plant growth / for photosynthesis / grow crops; less feed grown for livestock / livestock don’t survive so less meat or dairy production;

This question in 8291/21 Oct/Nov 2023

2 (a) A student investigates the concentration of nitrate ions in a lake. The student makes the following hypothesis: ‘The concentration of nitrate ions in lake water increases on hotter days.’ The student collects a sample of lake water on each of five days and records the air temperature on each day. The student measures the concentration of nitrate ions in each water sample. (i) State the independent variable in this investigation. … [1] (ii) State one variable the student should control in this investigation. … [1] (iii) Explain the benefit of repeating an investigation. … … … … [2] (b) Table 2.1 shows the student’s results. Table 2.1 air concentration of nitrate ions water sample temperature in mg / dm3 / °C 1 2.7 21 2 3.1 19 3 4.2 23 4 3.3 32 5 2.5 35 (i) Calculate the mean concentration of nitrate ions shown in Table 2.1. Give your answer to one decimal place. mean = … mg / dm3 [2] (ii) Calculate the air temperature range shown in Table 2.1. range = … °C [1] (iii) The student’s hypothesis for this investigation was: ‘The concentration of nitrate ions in lake water increases on hotter days.’ Interpret the data in Table 2.1 to conclude whether the student’s hypothesis is correct. Support your conclusion with evidence from Table 2.1. … … [1] (iv) Describe a systematic sampling strategy the student could use to collect the five water samples. … … [1] (v) One standard for drinking water in the United States is a maximum concentration of nitrate ions of 10 mg / dm3. The lake water has concentrations of nitrate ions lower than 10 mg / dm3. Suggest why it is not possible to conclude that the lake water is suitable to provide drinking water from only the results in Table 2.1. … … [1] (c) Water in drinking wells is at risk of contamination from nitrate ions. The map in Fig. 2.1 shows the location of drinking-water wells in the state of Minnesota in the United States and the concentration of nitrate ions in these wells. Key international border nitrate ion concentration in mg / dm3 state capital 3.0–10.0 >10.0 N Canada Lake North Superior Dakota Wisconsin Iowa Fig. 2.1 (i) Describe the distribution of nitrate ion concentration in drinking-water wells shown in Fig. 2.1. … … … … … … [3] (ii) State the process by which nitrate ions enter groundwater from soil. … [1] (d) Artesian wells can supply drinking water. State two other supply methods for drinking water. 1 … 2 … [2] (e) Polluted drinking water leads to water insecurity. Water insecurity leads to increased poverty. (i) Suggest reasons why water insecurity leads to poverty. … … … … [2] (ii) Explain how water insecurity can lead to lower levels of food production. … … … … [2] [Total: 20]

20 marks

Mark scheme: 2(a)(i) (air) temperature; 1 2(a)(ii) any one from: 1 volume / amount of water; collect water, in same way / at same depth; time of day / time of collection; location e.g. side of lake / position of sampling; 2(a)(iii) any two from: 2 results can be compared; anomalous results exclude / identifies anomalous results or outliers / identify mistakes; average/mean found; averaging/identifying anomalies increases accuracy; averaging reduces effect of random errors / reduces margin of error; confirm results / proves or disproves results; 2(b)(i) answer to one decimal place: 3.2; 2 unrounded answer: 3.16; 2(b)(ii) 16; 1 2(b)(iii) no; 1 AND any one from: valid evidence e.g. highest temperature and lowest concentration or correctly quoted data; no correlation (between air temperature and concentration of nitrate ions); 2(b)(iv) systematic sampling described e.g. every nth distance across lake selected; 1 2(b)(v) any one from: 1 data only gives information on nitrate; only five samples / not representative; may contain other pollutants / named pollutant; 2(c)(i) any three from: 3 nitrate concentrations (in wells) greatest in centre of state / towards middle / increases close to the state capital; cluster in southwest corner > 10.0 (mg /L ); between 3.0–10.0 (mg / L) in south east corner / between Wisconsin and Iowa; low concentrations along border with Lake Superior / in North / border with Canada; low concentrations around the state capital; 2(c)(ii) leaching; 1 2(d) any two from: 2 piped / from taps; aquifer; borehole; gravity-fed; reservoirs / dams; 2(e)(i) any two from: 2 people spend hours collecting water; cannot work / cannot earn money; cannot attend school / get an education; people drink contaminated water; people become ill (dehydrated / water-borne disease) so cannot work; less crops grown so less income for farmers / higher prices so cannot afford; 2(e)(ii) any two from: 2 limited or no irrigation; unreliable water supply / water available at wrong time for crop growth; water needed for plant growth / for photosynthesis / grow crops; less feed grown for livestock / livestock don’t survive so less meat or dairy production;

This question in 8291/23 Oct/Nov 2023

3 (a) A farmer investigates insect pests on soybean plants. Fig. 3.1 shows soybean plants. Fig. 3.1 The farmer investigates an area of soybean plants that is 7 rows by 7 columns. There is a total of 49 soybean plants. Fig. 3.2 shows the results from a random number generator. The farmer uses these results to select a sample of 6 soybean plants. Each number represents a row number and a column number. 56 71 29 56 33 22 32 60 53 28 23 72 13 Fig. 3.2 The farmer starts at number ‘56’. ‘56’ represents row 5 and column 6. The farmer circles this plant on Fig. 3.3. The farmer ignores a number in Fig. 3.2 if: • any part of the number is greater than 6 • a number is repeated. Fig. 3.3 shows the area of soybean plants the farmer investigates. column number 0 1 2 3 4 5 6 0 1 2 row 3 number 4 5 6 Fig. 3.3 (i) The farmer samples a total of 6 plants. The first 3 soybean plants selected from the random number generator are circled. Complete Fig. 3.3 by circling the 3 other soybean plants the farmer samples. [1] (ii) State one benefit of using a random number generator to select the soybean plants. … … [1] (b) The farmer uses a beating tray to investigate insect population. (i) Describe a beating tray method the student can use to estimate the total number of insects on the 49 soybean plants. … … … … … … … … … … [5] (ii) Describe two limitations of using a beating tray for investigating the insect population on soybean plants. 1 … … 2 … … [2] (c) The farmer concludes that the soybean plants are infested with aphids. Aphids are insects that eat soybean plants and reduce crop yield. The farmer introduces the harlequin beetle to the soybean plants. The harlequin beetle is a flying insect and is a predator of the aphids. Fig. 3.4 shows a harlequin beetle. 7 mm Fig. 3.4 The farmer records the population of aphids in 2 different fields. Fig. 3.5 shows the results. Key field 1: no predator field 2: predator added 300 250 200 mean number of aphids 150per leaf predator added to field 2 100 50 00 5 10 15 20 25 30 35 40 45 50 55 60 65 day Fig. 3.5 (i) Name the type of method for controlling the aphid population using a predator. … [1] (ii) Suggest why the predator was not added to field 1. … [1] (iii) Suggest why the aphid population was measured before the predator was added to field 2. … … [1] (iv) Write a conclusion using the data in Fig. 3.5. … … … … … … [3] (v) Suggest why the farmer covers the soybean plants with nets after the predator is added. … … … … [2] (d) The harlequin beetle was introduced to North America and Europe to control aphid populations. The harlequin beetle is now considered to be one of the world’s most invasive species. The harlequin beetle becomes inactive when temperatures are lower than 10 °C. Suggest why climate change could benefit the harlequin beetle. … … [1] (e) Increasing crop productivity by reducing pests is a strategy for managing food security. Hydroponics can also improve food security. (i) Explain how hydroponics improves food security. … … … … … … … … [4] (ii) Describe the limitations of large-scale food stockpiling as a method of reducing food insecurity. … … … … … … [3] (iii) Outline the impacts of food insecurity. … … … … … … … … [4] [Total: 29]

29 marks

Mark scheme: 3(a)(i) 3 plants circled correctly at 32, 60, 53; 1 3(a)(ii) avoids bias / equal chance of selection; 1 3(b)(i) method: 5 (on one plant) tap / hit / shake the plant (gently with a stick); collect falling insects on the beating tray; count (only) the insects; processing: repeat (the beating tray) method and take a mean; idea of scaling up; e.g. multiply the mean number of insects in the sampled area / plants sampled by the total number of plants 3(b)(ii) any two from: 2 soybean plants are close to ground so difficult to get lower insects in tray; beating can damage the plant; beating cannot be used on wet plants; flying insects fly away / some insects might escape; some insects left on plant / not all insects will fall on the tray; 3(c)(i) biological; 1 3(c)(ii) control / to compare the result; 1 3(c)(iii) any one from: 1 to ensure that field 1 and field 2 had a comparable number of aphids (at the start); to see if the predator has an effect; 3(c)(iv) predator reduces the aphid population; 3 predator takes 8–12 days to make an impact / it took 10 days for the introduced predator to work; relevant comparable quoted data e.g. difference in aphid population with no predator is 215 (255-40) by day 65; 3(c)(v) any two from: 2 prevents predator flying away; prevents new pests / insects landing on the plants; prevents new predators landing on the plants; (so that the farmer knows) it is the harlequin beetle predator that has reduced the aphid population; 3(d) any one from: 1 increased temperatures mean it will not become inactive; native species may die at hotter temperatures / in changed conditions; beetle competitors / predators might die; expand range of beetle; 3(e)(i) plants grown at high density / high crop yield (per unit area); 4 any three from: plants grown without soil / roots are in water that contains nutrients; plants less prone to soil pests; plants can be grown in areas with soil erosion / poor quality soil; plants can be grown inside; plants can be grown in controlled conditions; e.g. controlled lighting yields not dependent on weather conditions / rainfall; crops are not seasonal / can be grown all year; 3(e)(ii) any three from: 3 leads to food shortages; more likely to benefit rich; food could rot if not stored properly; danger of losing (large) quantity of food at one time; fresh food loses nutritional value if stored for long period; idea that food should be distributed to people who are hungry now; 3(e)(iii) any four from: 4 food scarcity; nutritional deficiency / malnutrition; famine / starvation; poverty; forces migration; conflict;

This question in 8291/21 Oct/Nov 2024

2 (a) Bats are flying nocturnal mammals. They are active at night time and feed on insects. Fig. 2.1 shows a bat. This species of bat has a wingspan of approximately 12 cm. Fig. 2.1 A biologist investigates bat activity using an electronic detector. The bats nest in a cave. The detector counts the number of bat flights into and out of the cave for 70 nights. The bat activity for each night is calculated as a percentage of the total activity for the 70-day period. The number of insects near the cave is recorded for the same number of nights. Fig. 2.2 shows the results. 5 4 3 percentage bat activity 2 1 0 0 10 20 30 40 50 60 70 day 150 100 number of insects 50 0 0 10 20 30 40 50 60 70 day Fig. 2.2 (i) Data is collected from a second electronic detector that does not record bat activity. Suggest why this data is collected. … … [1] (ii) The biologist hypothesises that bat activity increases when insect numbers increase. Conclude whether the data in Fig. 2.2 supports the biologist’s hypothesis. Give a reason to support your conclusion. … … [1] (iii) Suggest why the data in Fig. 2.2 is not used to predict the population of the bats in the cave. … … [1] (b) Bats travel between 0.5 km and 65 km to find food. Suggest how the distance bats travel from the cave for food can be investigated. … … … … [2] (c) Some species of bats are endangered. Explain the role of the Convention on International Trade in Endangered Species (CITES) in conserving bat populations. … … … … … … [3] (d) The data for the number of insects in Fig. 2.2 were collected using the large suction device shown in Fig. 2.3. Content removed due to copyright restrictions. Fig. 2.3 Suggest the benefits and limitations of using this large suction device to monitor insect population. benefits … … … … limitations … … … … [4] [Total: 12]

12 marks

Mark scheme: 2(a)(i) idea of a comparison with a control / identify anomalous results; 1 2(a)(ii) No and peak bat activity has low insect numbers / ORA; 1 2(a)(iii) data is only for bat activity / no information on number of bats / same bat could be counted numerous times or not counted 1 at all; 2(b) any two from: 2 fit tracking devices to the bats; monitor by GPS; use radio tracking; put electronic (motion) detectors at different distances from the cave; 2(c) any three from: 3 international agreement or cooperation; to ensure international trade in bats does not threaten the survival of the species / cause extinction; prevents illegal trade / poaching; provides information / updates on endangered status of species; raise awareness / education (of bats); 2(d) max four: 4 max three benefits: quicker than using other methods e.g. sweep net; a lot of insects collected; low skill level needed to operate; could survey a wide area; max three limitations: cost of equipment; insects may be killed or harmed; only collects insects where suction device is pointed; equipment might be heavy to use; requires fuel or battery (unlike a sweep net);

This question in 8291/22 Oct/Nov 2024

1 A report stated that people who live near waste incineration plants are less likely to recycle their waste. (a) A student uses a questionnaire to investigate this statement. Suggest three reasons why the student carries out a pilot survey before the questionnaire. 1 … … 2 … … 3 … … [3] (b) The student considers two different question styles for the questionnaire. style 1: tick (✓) yes or cross (✗) no Do you agree that living near to a waste incineration plant means you are less likely to recycle your waste? style 2: 1 = strongly agree 2 = agree 3 = neither agree nor disagree 4 = disagree 5 = strongly disagree To what extent do you agree that living near to a waste incineration plant means you are less likely to recycle your waste? Describe the benefits of the two different question styles. … … … … … … … [3] (c) The student then decides to carry out recorded interviews with some of the people in the survey. (i) Suggest the benefits of using recorded interviews. … … … … … [2] (ii) The student selects only women aged 40–50 years for the recorded interviews. State a limitation of this sampling method. … … … [1] (d) The student concludes that a lack of recycling facilities is the main reason people do not recycle their waste. (i) Suggest two reasons for a lack of recycling facilities. 1 … … 2 … … [2] (ii) Explain how financial incentives and legislation encourage more people to recycle their waste. … … … … … [2] (e) Explain the impacts of landfill as a method of waste disposal. … … … … … … … … … … [5] [Total: 18]

18 marks

Mark scheme: Question Answer Marks 1(a) any three from: 3 M1 smaller sample / easy to analyse / easy to process; M2 shows whether questions, are valid / are relevant / meet objectives / are successful / need changing / are understandable / can be answered / contain limitations / contain mistakes / are biased; M3 checks, response rate / target group is met / sampling strategy (is suitable) / sample location (is suitable); M4 shows, whether the questionnaire takes too long / how long questionnaire takes; 1(b) any three from: 3 style 1: M1 less data to analyse; M2 quick(er) (to analyse or complete); M3 simple(r) / more straightforward (to answer); style 2: M4 more information available / range of answers will be given / get an opinion / get a personal view; M5 quantitative data; 1(c)(i) any two from: 2 M1 reduces chance of altering results / permanent record / can go back and listen or watch again; M2 can give detailed answers / can explain answers / direct quotes can be used / allows for personal responses; M3 easy or quick to record answers / don’t need to write answers / suitable for illiterate people / more accessible / suitable for visually impaired people; M4 able to, record emotions or tone / see body language; M5 people may be, more honest / less likely to lie; 1(c)(ii) any one from: 1 M1 biased; M2 not representative / no males selected / no data from younger or older women / leaves out some of the population; 1(d)(i) any two from: 2 M1 cost / lack of funding / not profitable / expensive; M2 other priorities on finances; M3 other methods of waste disposal used e.g. landfill / incineration; M4 lack of land or space; M5 export waste to other countries; M6 limited collection opportunities / limited infrastructure for collection / difficult to transport recycled waste / lack of collection vehicles; M7 some waste used for energy generation (through incineration); M8 low population (density); 1(d)(ii) any two from: 2 M1 introduce, fine / charge / tax / penalty / sanction; M2 introduce, reward schemes / payment, for recycling; M3 waste not collected, if not sorted or not in recycle bins; M4 limit on amount of general rubbish or non-recycled rubbish, that will be collected; M5 people do not want to get in trouble / people obey laws; 1(e) any five from: 5 M1 risk of, leaching / release of toxic substances / named toxic substance e.g. heavy metals; M2 contamination of soil; M3 contamination of water; M4 emits or build-up of, methane / CH4; M5 greenhouse gases emitted / emitted gases lead to climate change or global warming; M6 visual / noise / odour, pollution; M7 risk of, vermin / pests; M8 risk of, disease / named disease; M9 bioaccumulation; M10 bioaccumulation described: toxic substances accumulate within an organism; M11 biomagnification; M12 biomagnification described: concentration of toxic substances increase up the food chain; M13 habitat loss / biodiversity loss; M14 stated impact on animals e.g. animals ingest plastic; M15 reduces illegal dumping of waste / stops waste ending up in, rivers / oceans; M16 creates jobs / improves local economy;

This question in 8291/21 May/June 2025

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

1 (a) A questionnaire is used to obtain the opinions of people in different regions on the importance of recycling. Fig. 1.1 shows the results. Key extremely important important not important 100 90 80 70 percentage of 60 responses 50 40 30 20 10 0 Europe Africa North Oceania America region Fig. 1.1 Compare the percentage of people in different regions who think recycling is extremely important. … … … … … … [3] (b) (i) There are three choices in the response area of this questionnaire: • extremely important • important • not important. Suggest one benefit and one limitation of this type of response area for a questionnaire. benefit … … limitation … … [2] (ii) A total of 11 500 local business owners and homeowners were used to complete the questionnaire. Suggest one benefit of asking these people to complete the questionnaire. … … [1] (c) Some people do not recycle even though they say that recycling is extremely important. Suggest three reasons why people do not recycle. 1 … 2 … 3 … [3] (d) Plastic waste can end up in the ocean. (i) Describe the impacts of plastics in oceans on marine life. … … … … … … … … [4] (ii) Some fishing boat owners collect the plastic waste. The plastic waste is converted into plastic fibres. Cotton is a plant which is harvested for its fibres. Both plastic fibres and cotton fibres are used to make clothing. Suggest two advantages for the environment of using plastic fibres compared to cotton fibres. 1 … … 2 … … [2] (e) A report states that 25% of plastic waste is incinerated. Describe the benefits and limitations of incineration as a method of plastic waste disposal. benefits … … … … limitations … … … … [4] [Total: 19]

19 marks

Mark scheme: Question Answer Marks 1(a) any three from: 3 MP1 most people in all regions view recycling as extremely important; MP2 Africa has highest percentage; MP3 Oceania has lowest percentage; MP4 comparative data quote e.g. Europe is greater than North America; 1(b)(i) any two from: 2 benefits (max 1): MP1 limits (detailed / explained) responses; MP2 easy to answer; MP3 quick to analyse; MP4 quantifiable; limitations (max 1): MP5 no category for, ‘do not know’ / no opinion / no personal response; MP6 limits detail in answers / does not allow for detailed answers; MP7 difficult to choose between the categories; 1(b)(ii) any one from: 1 MP1 representative sample; MP2 large sample; MP3 reduces bias; 1(c) any three from: 3 MP1 lack of facilities; MP2 lack of understanding of what can be recycled; MP3 lack of trust in recycling programmes; MP4 inconvenience / time consuming; MP5 lack of government support / legislation; MP6 existing waste disposal methods; 1(d)(i) any four stated or developed: 4 MP1 does not biodegrade; MP2 can be ingested by marine life / cause choking to marine life; MP3 can entangle marine life; MP4 risk of suffocation; MP5 form microplastics; MP6 bioaccumulation; MP7 bioaccumulation described; e.g. build-up of toxins within an organism / ingested faster than can excreted; MP8 biomagnification; MP9 biomagnification described: e.g. increase in concentration of pollutants up the food chain; 1(d)(ii) any two from plastic fibres: 2 MP1 can reduce land required for crops / land can be used to grow food instead; MP2 water not needed to water a crop; MP3 a method of recycling or disposing of plastic; MP4 reduces the plastic waste in the ocean; MP5 uses less energy; MP6 less CO2 produced; 1(e) any four from: 4 benefits (max 3): MP1 reduces quantity of waste / reduces waste in landfill; MP2 quick method; MP3 small area of land needed; MP4 heat generated can be used to heat homes or produce electricity / energy dense; MP5 safely disposes of plastics that are contaminated; limitations (max 3): MP6 produces toxic substances / air pollution; MP7 named example: e.g. particulates / acidic gases / NOx / CO2; MP8 stated impact or air pollution e.g. acid rain / global warming / respiratory problems / impact on crop yield; MP9 smell; MP10 need specialist equipment e.g. tall chimneys; MP11 (high) energy requirement;

This question in 8291/22 May/June 2025

1 (a) A questionnaire is used to obtain the opinions of people in different regions on the importance of recycling. Fig. 1.1 shows the results. Key extremely important important not important 100 90 80 70 percentage of 60 responses 50 40 30 20 10 0 Europe Africa North Oceania America region Fig. 1.1 Compare the percentage of people in different regions who think recycling is extremely important. … … … … … … [3] (b) (i) There are three choices in the response area of this questionnaire: • extremely important • important • not important. Suggest one benefit and one limitation of this type of response area for a questionnaire. benefit … … limitation … … [2] (ii) A total of 11 500 local business owners and homeowners were used to complete the questionnaire. Suggest one benefit of asking these people to complete the questionnaire. … … [1] (c) Some people do not recycle even though they say that recycling is extremely important. Suggest three reasons why people do not recycle. 1 … 2 … 3 … [3] (d) Plastic waste can end up in the ocean. (i) Describe the impacts of plastics in oceans on marine life. … … … … … … … … [4] (ii) Some fishing boat owners collect the plastic waste. The plastic waste is converted into plastic fibres. Cotton is a plant which is harvested for its fibres. Both plastic fibres and cotton fibres are used to make clothing. Suggest two advantages for the environment of using plastic fibres compared to cotton fibres. 1 … … 2 … … [2] (e) A report states that 25% of plastic waste is incinerated. Describe the benefits and limitations of incineration as a method of plastic waste disposal. benefits … … … … limitations … … … … [4] [Total: 19]

19 marks

Mark scheme: Question Answer Marks 1(a) any three from: 3 MP1 most people in all regions view recycling as extremely important; MP2 Africa has highest percentage; MP3 Oceania has lowest percentage; MP4 comparative data quote e.g. Europe is greater than North America; 1(b)(i) any two from: 2 benefits (max 1): MP1 limits (detailed / explained) responses; MP2 easy to answer; MP3 quick to analyse; MP4 quantifiable; limitations (max 1): MP5 no category for, ‘do not know’ / no opinion / no personal response; MP6 limits detail in answers / does not allow for detailed answers; MP7 difficult to choose between the categories; 1(b)(ii) any one from: 1 MP1 representative sample; MP2 large sample; MP3 reduces bias; 1(c) any three from: 3 MP1 lack of facilities; MP2 lack of understanding of what can be recycled; MP3 lack of trust in recycling programmes; MP4 inconvenience / time consuming; MP5 lack of government support / legislation; MP6 existing waste disposal methods; 1(d)(i) any four stated or developed: 4 MP1 does not biodegrade; MP2 can be ingested by marine life / cause choking to marine life; MP3 can entangle marine life; MP4 risk of suffocation; MP5 form microplastics; MP6 bioaccumulation; MP7 bioaccumulation described; e.g. build-up of toxins within an organism / ingested faster than can excreted; MP8 biomagnification; MP9 biomagnification described: e.g. increase in concentration of pollutants up the food chain; 1(d)(ii) any two from plastic fibres: 2 MP1 can reduce land required for crops / land can be used to grow food instead; MP2 water not needed to water a crop; MP3 a method of recycling or disposing of plastic; MP4 reduces the plastic waste in the ocean; MP5 uses less energy; MP6 less CO2 produced; 1(e) any four from: 4 benefits (max 3): MP1 reduces quantity of waste / reduces waste in landfill; MP2 quick method; MP3 small area of land needed; MP4 heat generated can be used to heat homes or produce electricity / energy dense; MP5 safely disposes of plastics that are contaminated; limitations (max 3): MP6 produces toxic substances / air pollution; MP7 named example: e.g. particulates / acidic gases / NOx / CO2; MP8 stated impact or air pollution e.g. acid rain / global warming / respiratory problems / impact on crop yield; MP9 smell; MP10 need specialist equipment e.g. tall chimneys; MP11 (high) energy requirement;

This question in 8291/23 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

4 (a) Fig. 4.1 shows a mayfly nymph in a river. Fig. 4.1 A student wants to sample the population of mayfly nymphs in a river. Fig. 4.2 shows the river. Fig. 4.2 (i) Suggest two safety precautions the student should take before using this river to sample mayfly nymphs. 1 … … 2 … … [2] (ii) Describe how kick sampling is used to investigate the population of mayfly nymphs in the river. … … … … … … … … … … [5] (b) The population of mayfly nymphs in river water is used as an indication of water quality. Fig. 4.3 shows data for the population of mayfly nymphs in rivers in an area of India. 100 90 80 70 60 population of 50 mayfly nymphs 40 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month Fig. 4.3 Fig. 4.4 shows data for the mean monthly pH of water from the same rivers in India. 10 9 8 7 6 water pH 5 4 3 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month Fig. 4.4 The student concludes that a water pH value of 7 provides the best conditions for mayfly nymphs. Discuss whether this conclusion is correct. … … … … [2] (c) Acid deposition can affect aquatic environments. (i) Outline the formation of acid deposition from the combustion of fossil fuels. … … … … … … … … [4] (ii) State two impacts of acid deposition other than on aquatic environments. 1 … … 2 … … [2] [Total: 15]

15 marks

Mark scheme: 4(a)(i) any two from: 2 M1 consider safe access; M2 know the depth; M3 (know the) structure of river bed; M4 (know the) flow or velocity of water; M5 (know the) direction of water flow; M6 (know the) weather forecast / risk of flash flooding; M7 wear appropriate or protective clothing; e.g., closed shoes or boots / gloves 4(a)(ii) any five from: 5 method of disturbance: M1 disturb or kick, riverbed; M2 disturb or kick for stated period; method of sampling: M3 use systematic or random sampling of site / or method described; location: M4 sample collected downstream of disturbance; M5 (opening of) net facing upstream; method of counting and processing: M6 idea of decanting sample into bucket; M7 identify mayfly nymph and count sample; M8 repeat and average (at same location); M9 repeat and average at different, times / location; 4(b) any two from: 2 M1 yes and highest abundance in May and pH 7; M2 no and September low abundance and pH 7; M3 no and other factors also influence abundance; 4(c)(i) any four from: 4 M1 deposition can be wet or dry; M2 fossil fuels contain sulfur (compounds); M3 (combustion of fossil fuels) releases sulfur dioxide or SO2 gas; M4 (sulfur dioxide or SO2) reacts with water and oxygen; M5 forms, sulfuric acid / H2SO4; 4(c)(ii) any two from: 2 M1 defoliation / loss of leaves (of plants or crops); M2 reduced crop yield; M3 (enhanced) chemical weathering; M4 damage to, limestone buildings / marble statues / metal structures; M5 (dry acid deposition) causes named health issue e.g., respiratory lung disease, asthma, bronchitis;

This question in 8291/21 Oct/Nov 2025

4 (a) Fig. 4.1 shows a mayfly nymph in a river. Fig. 4.1 A student wants to sample the population of mayfly nymphs in a river. Fig. 4.2 shows the river. Fig. 4.2 (i) Suggest two safety precautions the student should take before using this river to sample mayfly nymphs. 1 … … 2 … … [2] (ii) Describe how kick sampling is used to investigate the population of mayfly nymphs in the river. … … … … … … … … … … [5] (b) The population of mayfly nymphs in river water is used as an indication of water quality. Fig. 4.3 shows data for the population of mayfly nymphs in rivers in an area of India. 100 90 80 70 60 population of 50 mayfly nymphs 40 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month Fig. 4.3 Fig. 4.4 shows data for the mean monthly pH of water from the same rivers in India. 10 9 8 7 6 water pH 5 4 3 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month Fig. 4.4 The student concludes that a water pH value of 7 provides the best conditions for mayfly nymphs. Discuss whether this conclusion is correct. … … … … [2] (c) Acid deposition can affect aquatic environments. (i) Outline the formation of acid deposition from the combustion of fossil fuels. … … … … … … … … [4] (ii) State two impacts of acid deposition other than on aquatic environments. 1 … … 2 … … [2] [Total: 15]

15 marks

Mark scheme: 4(a)(i) any two from: 2 M1 consider safe access; M2 know the depth; M3 (know the) structure of river bed; M4 (know the) flow or velocity of water; M5 (know the) direction of water flow; M6 (know the) weather forecast / risk of flash flooding; M7 wear appropriate or protective clothing; e.g., closed shoes or boots / gloves 4(a)(ii) any five from: 5 method of disturbance: M1 disturb or kick, riverbed; M2 disturb or kick for stated period; method of sampling: M3 use systematic or random sampling of site / or method described; location: M4 sample collected downstream of disturbance; M5 (opening of) net facing upstream; method of counting and processing: M6 idea of decanting sample into bucket; M7 identify mayfly nymph and count sample; M8 repeat and average (at same location); M9 repeat and average at different, times / location; 4(b) any two from: 2 M1 yes and highest abundance in May and pH 7; M2 no and September low abundance and pH 7; M3 no and other factors also influence abundance; 4(c)(i) any four from: 4 M1 deposition can be wet or dry; M2 fossil fuels contain sulfur (compounds); M3 (combustion of fossil fuels) releases sulfur dioxide or SO2 gas; M4 (sulfur dioxide or SO2) reacts with water and oxygen; M5 forms, sulfuric acid / H2SO4; 4(c)(ii) any two from: 2 M1 defoliation / loss of leaves (of plants or crops); M2 reduced crop yield; M3 (enhanced) chemical weathering; M4 damage to, limestone buildings / marble statues / metal structures; M5 (dry acid deposition) causes named health issue e.g., respiratory lung disease, asthma, bronchitis;

This question in 8291/23 Oct/Nov 2025