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Gene pools: Edexcel A‑Level Biology B questions

Every Edexcel A-Level Biology B exam question on 8.3 Gene pools, 2016–2025, with its mark scheme and examiner’s report.

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1,826 questions

  1. Q6(b)(i)

    June 2025 · Paper 2

    3 marks8.3 Gene pools
    The whole paper ↗
    June 2025 Paper 2, question 6(b)(i): Calculate the expected number of rats that would be resistant to warfarin but do not require large amounts of vitamin K to survive, before warfarin was used. Us

  2. Q6(b)(ii)

    June 2025 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2025 Paper 2, question 6(b)(ii): Explain why, after two years, there is a change in the number of rats that are resistant to warfarin. (2)

  3. Q6(b)(iii)

    June 2025 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2025 Paper 2, question 6(b)(iii): Warfarin is highly toxic to rats that have no resistance. Explain why, after five years, there are still many rats that are not resistant to warfarin. (2)

  4. Q9(a)(i)

    June 2024 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2024 Paper 2, question 9(a)(i): The population of Asiatic lions in the zoo was initially started by breeding from nine lions. Explain why many of the next generations of lions died before they

  5. Q9(a)(ii)

    June 2024 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2024 Paper 2, question 9(a)(ii): Some of the young lions have a condition of the nervous system caused by a recessive allele. In wild populations of Asiatic lions, this recessive allele has a f

  6. Q9(a)(iii)

    June 2024 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2024 Paper 2, question 9(a)(iii): State two conditions that must occur for allele frequencies to stay constant over several generations. (2) 1 2

  7. Q5(c)(ii)

    June 2023 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2023 Paper 2, question 5(c)(ii): In 1755, a tsunami reduced the population to 20 people and there has been little immigration to the island. In 2022, the human population of Pingelap was approx

  8. Q8(c)(i)

    June 2023 · Paper 3

    3 marks8.3 Gene pools
    The whole paper ↗
    June 2023 Paper 3, question 8(c)(i): Calculate the probability that a person on this island is heterozygous for beta thalassaemia. Use the Hardy–Weinberg equation p2 + 2pq + q2 = 1 Give your answer

  9. Q8(c)(ii)

    June 2023 · Paper 3

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2023 Paper 3, question 8(c)(ii): Give two reasons why this value may not be accurate. (2)

  10. Q7(a)(iii)

    June 2022 · Paper 2

    3 marks8.3 Gene pools
    The whole paper ↗
    June 2022 Paper 2, question 7(a)(iii): In this population of 120 owls, 84 of them were grey. Calculate the number of owls that are heterozygous for feather colour. Use the Hardy-Weinberg equation p2

  11. Q7(b)

    June 2022 · Paper 2

    6 marks8.3 Gene pools
    The whole paper ↗
    June 2022 Paper 2, question 7(b): The scientists investigated the effect of climate change on the frequencies of these two alleles for feather colour in populations of tawny owls. The percentage

  12. Q4(b)(i)

    November 2021 · Paper 2

    3 marks8.3 Gene pools
    The whole paper ↗
    November 2021 Paper 2, question 4(b)(i): Calculate the number of heterozygous mosquitoes in 2015. Use the Hardy-Weinberg equation p2 + 2pq + q2 = 1 (3) Answer

  13. Q4(b)(ii)

    November 2021 · Paper 2

    4 marks8.3 Gene pools
    The whole paper ↗
    November 2021 Paper 2, question 4(b)(ii): Explain why the changes in the numbers of the resistant and non-resistant mosquitoes, from 2005 to 2018, are related to the function of the ace-1 gene. (4)

  14. Q9(b)(i)

    November 2021 · Paper 3

    3 marks8.3 Gene pools
    The whole paper ↗
    November 2021 Paper 3, question 9(b)(i): Explain why allele frequencies may cause problems in this population of potoroos. (3)

  15. Q5(c)(i)

    October 2020 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    October 2020 Paper 2, question 5(c)(i): Explain why in areas with low populations of orangutans, many of the orangutans have deformities and health problems. (2) .

  16. Q8(c)(i)

    October 2020 · Paper 2

    3 marks8.3 Gene pools
    The whole paper ↗
    October 2020 Paper 2, question 8(c)(i): Calculate the number of heterozygous people in the village. Use the Hardy-Weinberg equation p2 + 2pq+q2 = 1 (3) Answer

  17. Q7(c)(i)

    June 2019 · Paper 2

    4 marks8.3 Gene pools
    The whole paper ↗
    June 2019 Paper 2, question 7(c)(i): Calculate the number of heterozygous individuals in this population. Use the Hardy‑Weinberg equation (4) p2 + 2pq + q2 = 1 Answer

  18. Q7(c)(ii)

    June 2019 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2019 Paper 2, question 7(c)(ii): The frequency of Hers disease in most human populations is 1 in 40 000. Explain why the frequency of Hers disease is higher in the isolated population. (2)

  19. Q7(a)

    June 2018 · Paper 2

    1 mark8.3 Gene pools
    The whole paper ↗
    June 2018 Paper 2, question 7(a): The graph shows the frequency of a characteristic found in a population of animals. Frequency Characteristic Which type of selection would create this pattern?

  20. Q7(b)(ii)

    June 2018 · Paper 2

    2 marks8.3 Gene pools
    The whole paper ↗
    June 2018 Paper 2, question 7(b)(ii): Explain why, in 2016, the genetic biodiversity of the lynx population in the area where they had been reintroduced was much lower than in the protected area. (2
All 24 questions on Gene pools, as a list
  1. June 2025, Paper 2, Q6(b)(i) (3 marks): Calculate the expected number of rats that would be resistant to warfarin but do not require large amounts of vitamin K to survive, before warfarin was used. Us
  2. June 2025, Paper 2, Q6(b)(ii) (2 marks): Explain why, after two years, there is a change in the number of rats that are resistant to warfarin. (2)
  3. June 2025, Paper 2, Q6(b)(iii) (2 marks): Warfarin is highly toxic to rats that have no resistance. Explain why, after five years, there are still many rats that are not resistant to warfarin. (2)
  4. June 2024, Paper 2, Q9(a)(i) (2 marks): The population of Asiatic lions in the zoo was initially started by breeding from nine lions. Explain why many of the next generations of lions died before they
  5. June 2024, Paper 2, Q9(a)(ii) (2 marks): Some of the young lions have a condition of the nervous system caused by a recessive allele. In wild populations of Asiatic lions, this recessive allele has a f
  6. June 2024, Paper 2, Q9(a)(iii) (2 marks): State two conditions that must occur for allele frequencies to stay constant over several generations. (2) 1 2
  7. June 2023, Paper 2, Q5(c)(ii) (2 marks): In 1755, a tsunami reduced the population to 20 people and there has been little immigration to the island. In 2022, the human population of Pingelap was approx
  8. June 2023, Paper 3, Q8(c)(i) (3 marks): Calculate the probability that a person on this island is heterozygous for beta thalassaemia. Use the Hardy–Weinberg equation p2 + 2pq + q2 = 1 Give your answer
  9. June 2023, Paper 3, Q8(c)(ii) (2 marks): Give two reasons why this value may not be accurate. (2)
  10. June 2022, Paper 2, Q7(a)(iii) (3 marks): In this population of 120 owls, 84 of them were grey. Calculate the number of owls that are heterozygous for feather colour. Use the Hardy-Weinberg equation p2
  11. June 2022, Paper 2, Q7(b) (6 marks): The scientists investigated the effect of climate change on the frequencies of these two alleles for feather colour in populations of tawny owls. The percentage
  12. November 2021, Paper 2, Q4(b)(i) (3 marks): Calculate the number of heterozygous mosquitoes in 2015. Use the Hardy-Weinberg equation p2 + 2pq + q2 = 1 (3) Answer
  13. November 2021, Paper 2, Q4(b)(ii) (4 marks): Explain why the changes in the numbers of the resistant and non-resistant mosquitoes, from 2005 to 2018, are related to the function of the ace-1 gene. (4)
  14. November 2021, Paper 3, Q9(b)(i) (3 marks): Explain why allele frequencies may cause problems in this population of potoroos. (3)
  15. October 2020, Paper 2, Q5(c)(i) (2 marks): Explain why in areas with low populations of orangutans, many of the orangutans have deformities and health problems. (2) .
  16. October 2020, Paper 2, Q8(c)(i) (3 marks): Calculate the number of heterozygous people in the village. Use the Hardy-Weinberg equation p2 + 2pq+q2 = 1 (3) Answer
  17. June 2019, Paper 2, Q7(c)(i) (4 marks): Calculate the number of heterozygous individuals in this population. Use the Hardy‑Weinberg equation (4) p2 + 2pq + q2 = 1 Answer
  18. June 2019, Paper 2, Q7(c)(ii) (2 marks): The frequency of Hers disease in most human populations is 1 in 40 000. Explain why the frequency of Hers disease is higher in the isolated population. (2)
  19. June 2018, Paper 2, Q7(a) (1 mark): The graph shows the frequency of a characteristic found in a population of animals. Frequency Characteristic Which type of selection would create this pattern?
  20. June 2018, Paper 2, Q7(b)(ii) (2 marks): Explain why, in 2016, the genetic biodiversity of the lynx population in the area where they had been reintroduced was much lower than in the protected area. (2
  21. June 2018, Paper 3, Q8(b) (9 marks): Some health disorders, such as sickle cell anaemia, have a genetic basis. People who are at risk of these disorders can be identified using genetic tests. Hospi
  22. June 2017, Paper 2, Q7(b) (3 marks): The fur colour of animals can be affected by natural selection. Compare and contrast stabilising selection with disruptive selection. (3)
  23. June 2017, Paper 2, Q10(a)(ii) (2 marks): Explain why, although the population of seals has recovered, many of the seals have health problems. (2)
  24. June 2017, Paper 3, Q7(a) (4 marks): The incidence of babies born with cystic fibrosis in Australia is 1 in 2500. Use the Hardy Weinberg equation, p2 + 2pq + q2 = 1, to calculate the percentage of

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