plumiPopulation genetics and epigenetics: OCR A‑Level Biology B questions
Every OCR A-Level Biology B exam question on 5.1.2 Population genetics and epigenetics, 2016–2025, with its mark scheme and examiner’s report.
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Q36(b)(i)
The whole paper ↗![June 2025 Paper 1, question 36(b)(i): Explain why DNA methylation is not described as a DNA mutation. [3]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42201-jun25-36-bi-qp.webp?v=3)
Q36(b)(ii)
The whole paper ↗![June 2025 Paper 1, question 36(b)(ii): Describe the role of DNA methylation in the regulation of genes. [1]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42201-jun25-36-bii-qp.webp?v=3)
Q2(b)(i)
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Q2(b)(ii)
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Q34(c)(i)
The whole paper ↗![November 2021 Paper 1, question 34(c)(i): Using this example, explain what is meant by the term, genetic bottleneck. [3]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42201-nov21-34-ci-qp.webp?v=3)
Q34(c)(ii)
The whole paper ↗![November 2021 Paper 1, question 34(c)(ii): Give one possible cause for the genetic bottleneck event that affected C.siamensis. [1]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42201-nov21-34-cii-qp.webp?v=3)
Q1(d)(i)
The whole paper ↗![November 2021 Paper 2, question 1(d)(i): Explain how immunological and genetic factors would allow a population of wild rabbits to become more resistant to infection by MYXV. [2]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42202-nov21-01-di-qp.webp?v=3)
Q5(a)
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Q5(b)
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Q5(c)(ii)
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Q1(a)(ii)
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Q1(a)(iii)
The whole paper ↗![June 2019 Paper 2, question 1(a)(iii): Explain how the events described in (ii) resulted in the low genetic diversity of the Icelandic population. [2]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h42202-jun19-01-aiii-qp.webp?v=3)
Q2(d)(ii)
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Q2(d)(iii)
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All 21 questions on Population genetics and epigenetics, as a list
- June 2025, Paper 1, Q26 (1 mark): Cicadas are large insects. Two species of cicada live in the same habitat. Members of the two species are capable of interbreeding. • The breeding season of one
- June 2025, Paper 1, Q27 (1 mark): The Hardy-Weinberg principle uses the two equations below. p + q = 1.0 p2 + 2pq + q2 = 1.0 Which statement about the Hardy-Weinberg equations is correct? A p is
- June 2025, Paper 1, Q36(b)(i) (3 marks): Explain why DNA methylation is not described as a DNA mutation. [3]
- June 2025, Paper 1, Q36(b)(ii) (1 mark): Describe the role of DNA methylation in the regulation of genes. [1]
- June 2024, Paper 1, Q24 (1 mark): What is assessed using the Hardy-Weinberg principle? A Analysing observed and expected phenotypic ratios to see if there is a difference between them B Analysin
- June 2024, Paper 3, Q2(b)(i) (3 marks): Using the secondary data obtained by the student and the Hardy–Weinberg principle, estimate the number of people in the world that were heterozygous carriers of
- June 2024, Paper 3, Q2(b)(ii) (2 marks): Suggest two reasons why the use of the Hardy–Weinberg principle might not give an accurate estimate of the number of people in the world who are carriers of a m
- June 2022, Paper 1, Q14 (1 mark): Researchers studying a population of mona monkeys, Cercopithecus mona, noticed that one of the 490 monkeys had black fur rather than the usual grey and white fu
- November 2021, Paper 1, Q34(c)(i) (3 marks): Using this example, explain what is meant by the term, genetic bottleneck. [3]
- November 2021, Paper 1, Q34(c)(ii) (1 mark): Give one possible cause for the genetic bottleneck event that affected C.siamensis. [1]
- November 2021, Paper 2, Q1(d)(i) (2 marks): Explain how immunological and genetic factors would allow a population of wild rabbits to become more resistant to infection by MYXV. [2]
- November 2021, Paper 2, Q5(a) (4 marks): The following passage describes aspects of epigenetics. Complete the passage using the most appropriate terms. A mutation causes a change in the nucleotide sequ
- November 2021, Paper 2, Q5(b) (3 marks): Twenty zebrafish were exposed to hypoxia (oxygen deprivation) by keeping them in water with a low oxygen concentration for 4 weeks. All the offspring of these f
- November 2021, Paper 2, Q5(c)(ii) (3 marks): The OdsH gene causes male sterility in D. simulans – D. mauritiana hybrids. Based on the information provided, suggest how the OdsH gene has caused D. simulans
- June 2019, Paper 2, Q1(a)(ii) (2 marks): Allele frequencies will remain constant in a stable population. However, population changes can alter allele frequencies. For each of the following events, give
- June 2019, Paper 2, Q1(a)(iii) (2 marks): Explain how the events described in (ii) resulted in the low genetic diversity of the Icelandic population. [2]
- June 2019, Paper 2, Q2(d)(ii) (2 marks): It is estimated that 22% of all Europeans are homozygous for the recessive mutant form of DEFB126. Calculate the allele frequency of the mutant form of DEFB126
- June 2019, Paper 2, Q2(d)(iii) (1 mark): The fact that the DEFB126 mutation reduces the chances of successful fertilisation means that, in theory, the allele frequency should have fallen. Suggest why t
- June 2018, Paper 1, Q21 (1 mark): Which of the statements, A to D, is true of epigenetics? A Guanine is the most commonly methylated DNA base. B Identical twins show identical epigenetics. C Pro
- June 2017, Paper 1, Q3 (1 mark): The statements below relate to the epigenetic regulation of gene expression. Which of the following statements is/are correct? 1 Methylation of DNA prevents gen
- June 2017, Paper 1, Q31(c) (6 marks): The gene, HBB, codes for the beta polypeptide in haemoglobin. A person with sickle cell anaemia has a mutation in HBB. This causes a change to the sixth amino a
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