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Populations in ecosystems: AQA A‑Level Biology questions

Every AQA A-Level Biology exam question on 3.7.4 Populations in ecosystems, 2016–2025, with its mark scheme and examiner’s report.

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1,383 questions

  1. Q10.4

    June 2025 · Paper 2

    4 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 2, question 10.4: Natural regeneration of rainforests occurs by secondary succession (lines 8–10). Describe the process of secondary succession. [4 marks]

  2. Q10.5

    June 2025 · Paper 2

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 2, question 10.5: Farming practices have prevented the natural regeneration of rainforests by secondary succession (lines 12–14). Suggest two farming practices that prevent the n

  3. Q01.2

    June 2025 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 3, question 01.2: Microbiologists investigated the effect of two temperatures on the population growth of a species of bacterium. They grew separate bacterial cultures in identic

  4. Q03.2

    June 2025 · Paper 3

    3 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 3, question 03.2: The ecologists captured and marked the first sample of beetles during the second week of August. They identified the species of beetle before marking them. Use

  5. Q03.3

    June 2025 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 3, question 03.3: Use the data provided in Table 2 to estimate the population size of C. graminis. Show your working. [2 marks] Answer = beetles

  6. Q03.4

    June 2025 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2025 Paper 3, question 03.4: The ecologists repeated the investigation over a five–year period to monitor the population size of C. graminis. State two precautions they would have taken eac

  7. Q05.1

    June 2024 · Paper 2

    5 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 2, question 05.1: A weed is a plant growing where it is not wanted. Fat hen is a weed which grows in some crop fields. Describe how you could estimate the number of fat hen plant

  8. Q05.2

    June 2024 · Paper 2

    3 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 2, question 05.2: In potato plant fields, fat hen plants can grow up to a height of 2 m and absorb large quantities of nutrients from the soil. Fat hen has a negative effect on t

  9. Q05.3

    June 2024 · Paper 2

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 2, question 05.3: Table 1 gives some features of fat hen seeds. Table 1 Feature of seed Mean mass / mg 0.77 Maximum number produced per fat hen plant during a growing season 20 0

  10. Q10.5

    June 2024 · Paper 2

    3 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 2, question 10.5: Describe and explain two precautions required to ensure that the estimate of the size of the population of geckos was valid (lines 12–13). Do not include sample

  11. Q06.1

    June 2024 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 3, question 06.1: Define the biological term population. [2 marks] Ecologists monitored the biodiversity of birds in a protected woodland. They recorded the number of bird specie

  12. Q06.5

    June 2024 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 3, question 06.5: Suggest how the changes in the index of similarity in the bird community provide evidence for the process of succession. [2 marks]

  13. Q06.6

    June 2024 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2024 Paper 3, question 06.6: In Figure 5, the index of similarity for the last 10 years remains fairly constant. Name the stage of a succession this represents. Suggest one reason why the i

  14. Q07.1

    June 2023 · Paper 2

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2023 Paper 2, question 07.1: In the following passage, the numbered spaces can be filled with biological terms. An ecosystem supports a certain size of population of a species, called the (

  15. Q07.2

    June 2023 · Paper 2

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2023 Paper 2, question 07.2: Suggest two reasons for conserving rainforests. [2 marks] 1 2

  16. Q07.1

    June 2023 · Paper 3

    25 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2023 Paper 3, question 07.1: The importance of interactions between organisms and their environment. [25 marks] Or

  17. Q05.3

    June 2022 · Paper 2

    1 mark3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2022 Paper 2, question 05.3: Suggest one precaution needed when marking the lemurs to make sure the estimate of the number of lemurs is valid. [1 mark]

  18. Q05.4

    June 2022 · Paper 2

    1 mark3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2022 Paper 2, question 05.4: Using the information provided, calculate how many lemurs in the second sample were marked. [1 mark] Answer

  19. Q05.5

    June 2022 · Paper 3

    2 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    June 2022 Paper 3, question 05.5: Mature leaves from slow-growing, shade-tolerant plants produce poisonous chemicals that are a defence against being eaten by herbivores. Suggest how this benefi

  20. Q04.4

    November 2021 · Paper 2

    3 marks3.7.4 Populations in ecosystems
    The whole paper ↗
    November 2021 Paper 2, question 04.4: The first generation of a population of fruit flies had 50 females. Calculate how many female fruit flies would be produced from this population in the fifth ge
All 44 questions on Populations in ecosystems, as a list
  1. June 2025, Paper 2, Q10.4 (4 marks): Natural regeneration of rainforests occurs by secondary succession (lines 8–10). Describe the process of secondary succession. [4 marks]
  2. June 2025, Paper 2, Q10.5 (2 marks): Farming practices have prevented the natural regeneration of rainforests by secondary succession (lines 12–14). Suggest two farming practices that prevent the n
  3. June 2025, Paper 3, Q01.2 (2 marks): Microbiologists investigated the effect of two temperatures on the population growth of a species of bacterium. They grew separate bacterial cultures in identic
  4. June 2025, Paper 3, Q03.2 (3 marks): The ecologists captured and marked the first sample of beetles during the second week of August. They identified the species of beetle before marking them. Use
  5. June 2025, Paper 3, Q03.3 (2 marks): Use the data provided in Table 2 to estimate the population size of C. graminis. Show your working. [2 marks] Answer = beetles
  6. June 2025, Paper 3, Q03.4 (2 marks): The ecologists repeated the investigation over a five–year period to monitor the population size of C. graminis. State two precautions they would have taken eac
  7. June 2024, Paper 2, Q05.1 (5 marks): A weed is a plant growing where it is not wanted. Fat hen is a weed which grows in some crop fields. Describe how you could estimate the number of fat hen plant
  8. June 2024, Paper 2, Q05.2 (3 marks): In potato plant fields, fat hen plants can grow up to a height of 2 m and absorb large quantities of nutrients from the soil. Fat hen has a negative effect on t
  9. June 2024, Paper 2, Q05.3 (2 marks): Table 1 gives some features of fat hen seeds. Table 1 Feature of seed Mean mass / mg 0.77 Maximum number produced per fat hen plant during a growing season 20 0
  10. June 2024, Paper 2, Q10.5 (3 marks): Describe and explain two precautions required to ensure that the estimate of the size of the population of geckos was valid (lines 12–13). Do not include sample
  11. June 2024, Paper 3, Q06.1 (2 marks): Define the biological term population. [2 marks] Ecologists monitored the biodiversity of birds in a protected woodland. They recorded the number of bird specie
  12. June 2024, Paper 3, Q06.5 (2 marks): Suggest how the changes in the index of similarity in the bird community provide evidence for the process of succession. [2 marks]
  13. June 2024, Paper 3, Q06.6 (2 marks): In Figure 5, the index of similarity for the last 10 years remains fairly constant. Name the stage of a succession this represents. Suggest one reason why the i
  14. June 2023, Paper 2, Q07.1 (2 marks): In the following passage, the numbered spaces can be filled with biological terms. An ecosystem supports a certain size of population of a species, called the (
  15. June 2023, Paper 2, Q07.2 (2 marks): Suggest two reasons for conserving rainforests. [2 marks] 1 2
  16. June 2023, Paper 3, Q07.1 (25 marks): The importance of interactions between organisms and their environment. [25 marks] Or
  17. June 2022, Paper 2, Q05.3 (1 mark): Suggest one precaution needed when marking the lemurs to make sure the estimate of the number of lemurs is valid. [1 mark]
  18. June 2022, Paper 2, Q05.4 (1 mark): Using the information provided, calculate how many lemurs in the second sample were marked. [1 mark] Answer
  19. June 2022, Paper 3, Q05.5 (2 marks): Mature leaves from slow-growing, shade-tolerant plants produce poisonous chemicals that are a defence against being eaten by herbivores. Suggest how this benefi
  20. November 2021, Paper 2, Q04.4 (3 marks): The first generation of a population of fruit flies had 50 females. Calculate how many female fruit flies would be produced from this population in the fifth ge
  21. November 2021, Paper 2, Q09.1 (3 marks): Describe a method that could be used to determine the mean percentage cover of algae on a coral reef. Do not include information on the difficulties of using yo
  22. November 2021, Paper 2, Q09.2 (2 marks): Explain how succession results in a wide variety of fish living on coral reefs. Do not describe the process of succession in your answer. [2 marks]
  23. November 2021, Paper 2, Q09.3 (5 marks): Using all the information, evaluate the effect of the two fish species on algal growth on coral reefs. [5 marks]
  24. November 2021, Paper 2, Q10.4 (4 marks): The mark-release-recapture method can be used to estimate the size of a fish population (lines 13–14). Explain how. [4 marks]
  25. November 2021, Paper 2, Q10.5 (1 mark): Suggest why the mark-release-recapture method can produce unreliable results in very large lakes (lines 14–15). [1 mark]
  26. November 2021, AS Paper 1, Q07.3 (4 marks): The student wanted to use the data from plot 1 to estimate the total number of the beetle species in the meadow. Suggest how the student should use the data fro
  27. November 2020, Paper 3, Q02.1 (1 mark): Name the type of competition between livestock and ibex. [1 mark] Livestock will outcompete ibex if they: • are in the same habitat • eat a similar diet.
  28. November 2020, Paper 3, Q02.2 (3 marks): There must be a balance between the need for conservation of the ibex and the need for farmers to keep livestock. Using all the information, suggest and explain
  29. June 2019, Paper 2, Q01.1 (4 marks): Succession occurs in natural ecosystems. Describe and explain how succession occurs. [4 marks]
  30. June 2019, Paper 2, Q09.1 (5 marks): Describe how you could estimate the size of a population of sundews in a small marsh. [5 marks]
  31. June 2018, Paper 2, Q04.1 (3 marks): Describe how you would determine the mean percentage cover for beach grass on a sand dune. [3 marks]
  32. June 2018, Paper 2, Q04.2 (4 marks): The scientists concluded that the results shown in Figure 5 were due to succession taking place. Use Figure 5 to explain why the scientists reached this conclus
  33. June 2018, Paper 2, Q04.3 (1 mark): Use Figure 5 to explain the results in Figure 6. [1 mark]
  34. June 2017, Paper 2, Q02.1 (2 marks): Explain how using the SIT could reduce transmission of dengue. [2 marks]
  35. June 2017, Paper 2, Q02.2 (3 marks): Describe how the mark-release-recapture method could be used to determine the population of A. aegypti at the start of the investigation. [3 marks]
  36. June 2017, Paper 2, Q02.3 (1 mark): The release of radiation-sterilised A. aegypti has not been very successful in controlling the transmission of dengue. Suggest one reason why. [1 mark]
  37. June 2017, Paper 2, Q02.4 (1 mark): Recently a new method was developed to control A. aegypti. Scientists produced transgenic males carrying a ‘lethal gene’ which kills their offspring before they
  38. June 2017, Paper 2, Q02.5 (2 marks): The release of transgenic males proved successful in reducing the number of A. aegypti. Describe how the results in Figure 2 support this conclusion. [2 marks]
  39. June 2017, Paper 2, Q05.2 (1 mark): Suggest one way in which AMF may benefit from their association with plants. [1 mark]
  40. Specimen, Paper 3, Q01.1 (2 marks): The ecologists captured insects from a number of sites on the island. Suggest how they decided where to take their samples. [2 marks] 0 1 . 1
  41. Specimen, Paper 3, Q01.2 (2 marks): 1 2
  42. Specimen, Paper 3, Q01.3 (2 marks): Suggest the advantage of using the fluorescent powder in this experiment. [2 marks] 0 1 . 3
  43. Specimen, Paper 3, Q01.4 (2 marks): Answer =
  44. Specimen, Paper 3, Q01.5 (2 marks): The ecologists expected to obtain the same result from their calculations of the number of insects on this island on each day during the period 1–5 days after r

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