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Patterns of inheritance: OCR A‑Level Biology A questions

Every OCR A-Level Biology A exam question on 6.1.2 Patterns of inheritance, 2016–2025, with its mark scheme and examiner’s report.

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1,984 questions

  1. Q12

    June 2025 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 12: Artificial selection and natural selection are similar processes. Which option describes only natural selection? A Alleles are passed on to the next generation.

  2. Q13

    June 2025 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 13: Reproduction can be sexual or asexual. What is an advantage of sexual reproduction? A Advantageous features are preserved between generations. B Genetic variati

  3. Q17(b)(ii)

    June 2025 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 17(b)(ii): Suggest why female mammals cannot produce male offspring by parthenogenesis. [1]

  4. Q20(a)(i)

    June 2025 · Paper 2

    3 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 20(a)(i): Sweet pea is another species of plant. • Sweet pea flower colour is coded for by a gene with two alleles: blue (B) and red (b). • Sweet pea pollen shape is code

  5. Q20(a)(ii)

    June 2025 · Paper 2

    2 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 20(a)(ii): Explain why epistasis affects the offspring ratio in a genetic cross. [2]

  6. Q20(b)(i)

    June 2025 · Paper 2

    3 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 20(b)(i): Use the Hardy–Weinberg principle to calculate the number of heterozygous individuals in the greenhouse. Use the equations: p + q = 1 p2 + 2pq + q2 = 1 Number of

  7. Q20(b)(ii)

    June 2025 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2025 Paper 2, question 20(b)(ii): Estimates made by using the Hardy–Weinberg principle can be inaccurate. Use the information above to suggest one reason why the answer calculated in part (b)(i)

  8. Q5

    June 2024 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2024 Paper 2, question 5: Variation can be under genetic control. Which statement about the genetic control of variation cannot be true for discontinuous variation? A Variation is contro

  9. Q5(a)

    June 2024 · Paper 3

    6 marks6.1.2 Patterns of inheritance5.1.4 Hormonal communication
    The whole paper ↗
    June 2024 Paper 3, question 5(a): Type 1 diabetes mellitus is characterised by a lack of insulin production. Type 2 diabetes mellitus can involve reduced production of insulin and a decreased re

  10. Q4

    June 2023 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 2, question 4: Scientists crossed two plants that were heterozygous for two different genes. Both plants had the same genotype, AaBb. The genotypes and ratios of the offspring

  11. Q12

    June 2023 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 2, question 12: The modern pedigree dog breeds have been produced by many years of selective breeding. Which option does not explain why genetic disorders are common in pedigre

  12. Q13

    June 2023 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 2, question 13: What step could be taken to reduce the occurrence of genetic disorders in pedigree dogs? A Breeding only with individuals that meet the official breed descripti

  13. Q3(c)

    June 2023 · Paper 3

    4 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 3, question 3(c): Two characteristics that farmers have selectively bred in maize are colour and kernel (fruit) shape. Colour is determined by a gene with two alleles: • Allele A

  14. Q4(b)(i)

    June 2023 · Paper 3

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 3, question 4(b)(i): State the term for a large decrease in population size that reduces the gene pool. [1]

  15. Q4(b)(iii)

    June 2023 · Paper 3

    4 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2023 Paper 3, question 4(b)(iii): The kakapo and two other species of bird, the kaka and the kea, evolved from a common ancestor approximately 70 million years ago. The evolutionary timeline of

  16. Q5(c)

    June 2022 · Paper 3

    2 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    June 2022 Paper 3, question 5(c): The Hardy-Weinberg principle can be used to calculate allele and genotype frequencies in populations. The common morning glory plant, Ipomoea purpurea, has a ra

  17. Q19(a)(i)

    November 2021 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    November 2021 Paper 2, question 19(a)(i): The chromosomes used to determine sex inheritance are given different letters in birds and mammals. Identify one other way in which the sex determination in bir

  18. Q19(a)(ii)

    November 2021 · Paper 2

    4 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    November 2021 Paper 2, question 19(a)(ii): A pigeon is a bird. The colour of pigeon feathers is determined by a single gene on the Z chromosome. The feather colour gene has three alleles. ZA = red ZB = b

  19. Q19(b)(i)

    November 2021 · Paper 2

    2 marks6.1.2 Patterns of inheritance
    The whole paper ↗
    November 2021 Paper 2, question 19(b)(i): A student performed a chi squared calculation on the phenotypes of the actual nine children. Part of the calculation is shown in Table 19.1. (O–E)2 Observed Exp

  20. Q19(b)(ii)

    November 2021 · Paper 2

    1 mark6.1.2 Patterns of inheritance
    The whole paper ↗
    November 2021 Paper 2, question 19(b)(ii): Table 19.2 shows part of a statistical table for the chi squared test. 99 95 90 10 5.0 1.0 0.5 p% v = 1 .0001 .0039 .0158 2.706 3.841 6.635 7.879 2 .0201 0.103
All 57 questions on Patterns of inheritance, as a list
  1. June 2025, Paper 2, Q12 (1 mark): Artificial selection and natural selection are similar processes. Which option describes only natural selection? A Alleles are passed on to the next generation.
  2. June 2025, Paper 2, Q13 (1 mark): Reproduction can be sexual or asexual. What is an advantage of sexual reproduction? A Advantageous features are preserved between generations. B Genetic variati
  3. June 2025, Paper 2, Q17(b)(ii) (1 mark): Suggest why female mammals cannot produce male offspring by parthenogenesis. [1]
  4. June 2025, Paper 2, Q20(a)(i) (3 marks): Sweet pea is another species of plant. • Sweet pea flower colour is coded for by a gene with two alleles: blue (B) and red (b). • Sweet pea pollen shape is code
  5. June 2025, Paper 2, Q20(a)(ii) (2 marks): Explain why epistasis affects the offspring ratio in a genetic cross. [2]
  6. June 2025, Paper 2, Q20(b)(i) (3 marks): Use the Hardy–Weinberg principle to calculate the number of heterozygous individuals in the greenhouse. Use the equations: p + q = 1 p2 + 2pq + q2 = 1 Number of
  7. June 2025, Paper 2, Q20(b)(ii) (1 mark): Estimates made by using the Hardy–Weinberg principle can be inaccurate. Use the information above to suggest one reason why the answer calculated in part (b)(i)
  8. June 2024, Paper 2, Q5 (1 mark): Variation can be under genetic control. Which statement about the genetic control of variation cannot be true for discontinuous variation? A Variation is contro
  9. June 2024, Paper 3, Q5(a) (6 marks): Type 1 diabetes mellitus is characterised by a lack of insulin production. Type 2 diabetes mellitus can involve reduced production of insulin and a decreased re
  10. June 2023, Paper 2, Q4 (1 mark): Scientists crossed two plants that were heterozygous for two different genes. Both plants had the same genotype, AaBb. The genotypes and ratios of the offspring
  11. June 2023, Paper 2, Q12 (1 mark): The modern pedigree dog breeds have been produced by many years of selective breeding. Which option does not explain why genetic disorders are common in pedigre
  12. June 2023, Paper 2, Q13 (1 mark): What step could be taken to reduce the occurrence of genetic disorders in pedigree dogs? A Breeding only with individuals that meet the official breed descripti
  13. June 2023, Paper 3, Q3(c) (4 marks): Two characteristics that farmers have selectively bred in maize are colour and kernel (fruit) shape. Colour is determined by a gene with two alleles: • Allele A
  14. June 2023, Paper 3, Q4(b)(i) (1 mark): State the term for a large decrease in population size that reduces the gene pool. [1]
  15. June 2023, Paper 3, Q4(b)(iii) (4 marks): The kakapo and two other species of bird, the kaka and the kea, evolved from a common ancestor approximately 70 million years ago. The evolutionary timeline of
  16. June 2022, Paper 3, Q5(c) (2 marks): The Hardy-Weinberg principle can be used to calculate allele and genotype frequencies in populations. The common morning glory plant, Ipomoea purpurea, has a ra
  17. November 2021, Paper 2, Q19(a)(i) (1 mark): The chromosomes used to determine sex inheritance are given different letters in birds and mammals. Identify one other way in which the sex determination in bir
  18. November 2021, Paper 2, Q19(a)(ii) (4 marks): A pigeon is a bird. The colour of pigeon feathers is determined by a single gene on the Z chromosome. The feather colour gene has three alleles. ZA = red ZB = b
  19. November 2021, Paper 2, Q19(b)(i) (2 marks): A student performed a chi squared calculation on the phenotypes of the actual nine children. Part of the calculation is shown in Table 19.1. (O–E)2 Observed Exp
  20. November 2021, Paper 2, Q19(b)(ii) (1 mark): Table 19.2 shows part of a statistical table for the chi squared test. 99 95 90 10 5.0 1.0 0.5 p% v = 1 .0001 .0039 .0158 2.706 3.841 6.635 7.879 2 .0201 0.103
  21. November 2021, Paper 2, Q19(b)(iii) (2 marks): The calculated value for χ2 was below the critical value. The student concluded that their expected ratio of 2 : 1 : 1 was incorrect and should be rejected. Eva
  22. November 2021, Paper 2, Q19(c) (2 marks): Hypophosphatemic rickets is a sex-linked condition. The diagram shows the occurrence of hypophosphatemic rickets in a single family. healthy male healthy female
  23. November 2021, Paper 2, Q20(a)(i) (1 mark): Identify the modal beak size of G. fuliginosa. Size = arbitrary units [1]
  24. November 2021, Paper 2, Q20(a)(ii) (2 marks): Calculate the range of G. fuliginosa beak size as a proportion of the range of G. fortis beak size. Give your answer to 2 significant figures. Proportion = [2]
  25. November 2021, Paper 2, Q20(a)(iii) (3 marks): The scientists concluded that the data showed evidence of disruptive selection in the population of G. fortis. In disruptive selection, extreme phenotypes are s
  26. November 2021, Paper 2, Q20(b)(i) (1 mark): Name the type of speciation that occurs when two populations live in the same location. [1]
  27. November 2021, Paper 2, Q20(b)(ii) (1 mark): Suggest how G. fortis with large beaks could become reproductively isolated from G. fortis with small beaks despite living in the same location. [1]
  28. November 2021, Paper 2, Q20(c) (6 marks): Charles Darwin visited the Galapagos Islands in the 1820s. The organisms living on the Galapagos Islands provided Darwin with evidence that helped him to develo
  29. November 2021, Paper 3, Q1(c)(ii) (1 mark): Explain how the high occurrence of CPF in West Highland Terriers could have been a result of artificial selection. [1]
  30. November 2020, Paper 2, Q7 (1 mark): Scientists self-pollinated some pea plants that were heterozygous for the gene controlling height. 7 They expected a 3:1 ratio of tall plants to short plants in
  31. November 2020, Paper 2, Q18(b)(i) (4 marks): Represent the data in the table as a bar chart on the grid provided below. [4]
  32. November 2020, Paper 2, Q18(b)(ii) (3 marks): Since 1940, people have believed that the ability to roll the tongue is caused by a single gene with two alleles. R is dominant and allows tongue-rolling. r is
  33. November 2020, Paper 2, Q18(b)(iii) (2 marks): Individuals within populations vary. Much of this variation is under genetic control. The Hardy-Weinberg principle might not give an accurate estimate of the pr
  34. November 2020, Paper 2, Q19(a)(ii) (2 marks): Suggest why Hydra reproduces asexually when conditions are favourable. .. [2]
  35. November 2020, Paper 2, Q19(b)(i) (6 marks): When conditions are not favourable, Hydra reproduces sexually. This often happens in the winter. Cells in the body wall produce sperms and eggs by meiosis. Larg
  36. November 2020, Paper 2, Q19(b)(ii) (1 mark): [1]
  37. June 2019, Paper 2, Q6 (1 mark): Meiosis is an important feature of sexual reproduction. Which of the following processes occurs during meiosis and contributes to genetic variation in the offsp
  38. June 2019, Paper 2, Q8 (1 mark): Which of the following is not associated with the use of artificial selection in farm animals? A health problems in more productive breeds B inbreeding C increa
  39. June 2019, Paper 2, Q13 (1 mark): The ability to roll one’s tongue is under the control of a single gene. The gene has two alleles R and r. People who can roll their tongues can have the genotyp
  40. June 2019, Paper 3, Q4(b) (6 marks): (b)* The specific immune response involves B and T lymphocytes. There is variation in specific immune responses between individual animals. Variation between im
  41. June 2018, Paper 2, Q18 (6 marks): 18* For centuries, artificial selection has been used to improve the quality of crop plants used for human consumption. Explain, with reference to selective bre
  42. June 2018, Paper 2, Q20(b)(ii) (2 marks): It is thought that the modern cheetah population has low genetic diversity because the population, relatively recently, experienced a genetic bottleneck. Explai
  43. June 2018, Paper 2, Q20(b)(iii) (2 marks): Scientists are concerned about genetic drift in the remaining cheetah populations. Explain why genetic drift is likely to be of particular concern in the popula
  44. June 2018, Paper 2, Q20(c)(ii) (4 marks): When the island of Madagascar became separated from the African continent, there were no members of the cat family, Felidae, on the island. Outline how a fossa
  45. June 2018, Paper 2, Q20(c)(iii) (3 marks): Islands, such as Madagascar, often have species that are different from those on the nearest land mass because they are reproductively isolated. State three oth
  46. June 2018, Paper 3, Q1(c)(i) (3 marks): Identify the following: The genotype of the white onion plant The genotype of the red onion plant The phenotype of the offspring [3]
  47. June 2018, Paper 3, Q1(c)(ii) (1 mark): State the type of gene interaction shown by the genes A/a and B/b. [1]
  48. June 2018, Paper 3, Q4(a)(ii) (4 marks): Fig. 4 shows the inheritance pattern of agammaglobulinemia in a family. Key 1 2 male with agammaglobulinemia female with agammaglobulinemia 3 6 4 5 healthy male
  49. June 2018, Paper 3, Q4(b)(i) (1 mark): Two carriers of Vici syndrome have six children. Calculate how many of the six children you would expect to: • have Vici syndrome • be carriers of Vici syndrome
  50. June 2018, Paper 3, Q4(b)(ii) (1 mark): A daughter of these parents and a male carrier of Vici syndrome have a child. Calculate the probability of the child having Vici syndrome. Answer = [1]
  51. June 2017, Paper 2, Q17(a)(i) (1 mark): List the gametes that would be produced by a sweet pea plant that was heterozygous for both seed colour and shape. [1]
  52. June 2017, Paper 2, Q17(a)(ii) (2 marks): List the genotypes of the offspring that were produced from Mendel’s cross and state the corresponding phenotypes. genotypes phenotypes [2]
  53. June 2017, Paper 2, Q17(b)(i) (3 marks): Use the chi-squared formula | = E You may use the table below for working out. |2 = [3] 14 Table 17 shows a |2 probability table. Degrees Probability (p) of 0.9
  54. June 2017, Paper 2, Q17(b)(ii) (3 marks): After analysing the results, the students stated that the inheritance of the seed colour and shape in their investigation was different from that in Mendel’s in
  55. June 2017, Paper 2, Q17(b)(iii) (3 marks): A ratio that is different from the expected 9 : 3 : 3 : 1, in a cross such as this, can be the result of epistasis. Suggest and explain one reason, other than e
  56. June 2017, Paper 2, Q17(c)(ii) (1 mark): With reference to the proteins coded for by the seed colour gene, explain why the y allele is recessive. [1]
  57. June 2017, Paper 3, Q3(b) (3 marks): One subspecies of tiger is the Bengal tiger. One in 10 000 Bengal tiger births results in a white Bengal tiger. White Bengal tigers (shown in Fig. 3.1b on the i

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