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Inheritance and cystic fibrosis: Edexcel A‑Level Biology A questions

Every Edexcel A-Level Biology A exam question on Inheritance and cystic fibrosis (specification points 2.13–2.14), 2016–2025, with its mark scheme and examiner’s report.

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1,749 questions

  1. Q3(b)(i)

    June 2025 · Paper 3

    1 markInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 Paper 3, question 3(b)(i): Individual T was heterozygous for this mutation. State whether this mutation is dominant or recessive. (1)

  2. Q3(b)(ii)

    June 2025 · Paper 3

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 Paper 3, question 3(b)(ii): Scientists suggested this was a new mutation in this family originating in the genome of individual T. Explain why the scientists suggested this. (2)

  3. Q3(a)(i)

    June 2025 · AS Paper 1

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 AS Paper 1, question 3(a)(i): State what is meant by the following terms. (2) Genotype Phenotype

  4. Q3(a)(ii)

    June 2025 · AS Paper 1

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 AS Paper 1, question 3(a)(ii): Explain the type of inheritance shown in this example. (2)

  5. Q3(b)(i)

    June 2025 · AS Paper 1

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 AS Paper 1, question 3(b)(i): Draw a genetic diagram to find the expected ratio of the phenotypes of the offspring. (3) Ratio of named phenotypes:

  6. Q3(b)(ii)

    June 2025 · AS Paper 1

    1 markInheritance and cystic fibrosis
    The whole paper ↗
    June 2025 AS Paper 1, question 3(b)(ii): A statistical test can be used to compare observed and expected frequencies of the different phenotypes. Which statistical test is used to compare observed and

  7. Q7(b)(ii)

    June 2024 · Paper 2

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2024 Paper 2, question 7(b)(ii): The diagram shows three family pedigrees. Each pedigree shows the inheritance of a different genetic condition. Only one of the pedigree diagrams definitely sho

  8. Q2(a)

    June 2024 · AS Paper 1

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2024 AS Paper 1, question 2(a): Deduce why heterozygous snapdragon plants produce flowers with pink petals. (3)

  9. Q2(b)(i)

    June 2024 · AS Paper 1

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2024 AS Paper 1, question 2(b)(i): Two snapdragon plants with genotype FRFW were crossed. Determine the probability of each petal colour in the offspring of this cross, using a genetic diagram. (

  10. Q2(b)(ii)

    June 2024 · AS Paper 1

    1 markInheritance and cystic fibrosis
    The whole paper ↗
    June 2024 AS Paper 1, question 2(b)(ii): There were 416 plants produced from this cross. Predict how many of these plants will have flowers with white petals. (1)

  11. Q5(b)

    June 2024 · AS Paper 1

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2024 AS Paper 1, question 5(b): Some people have DNA polymerase that cannot detect and correct errors in DNA replication. These people have an increased risk of developing cancer. The increase

  12. Q4(c)

    June 2023 · Paper 2

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 2, question 4(c): Genetic screening can be used to test for conditions such as cystic fibrosis. Explain why cystic fibrosis affects digestion. (3)

  13. Q9(a)(i)

    June 2023 · Paper 2

    1 markInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 2, question 9(a)(i): The family pedigree shows the inheritance of this condition in one family. Key: = male without RP = female without RP = male with RP = female with RP It is poss

  14. Q6(b)(ii)

    June 2023 · Paper 3

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 3, question 6(b)(ii): Deduce the pattern of inheritance of the spots and long fin phenotypes. (2)

  15. Q6(c)(i)

    June 2023 · Paper 3

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 3, question 6(c)(i): Complete the table by filling in the missing genotypes and phenotypes. (2) Parent 1 gametes DN Dn dN dn Genotypes and phenotypes of offspring DDNN DDNn DdNN DdN

  16. Q6(c)(ii)

    June 2023 · Paper 3

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 3, question 6(c)(ii): The table contains the observed and expected results of this cross. Observed Expected Phenotype number number stripes and long fins 270 288 stripes and short fi

  17. Q6(c)(iii)

    June 2023 · Paper 3

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 Paper 3, question 6(c)(iii): Some critical values for the chi squared test ( χ2) are given in the table. Critical value degrees of freedom p = 0.05 p = 0.01 1 3.84 6.64 2 5.99 9.21 3 7.82 1

  18. Q4(a)(i)

    June 2023 · AS Paper 1

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 AS Paper 1, question 4(a)(i): State what is meant by the term allele. (2)

  19. Q4(a)(ii)

    June 2023 · AS Paper 1

    3 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 AS Paper 1, question 4(a)(ii): When a round‑eyed fruit fly is crossed with a bar‑eyed fruit fly, offspring are produced that have wide bar eyes. Explain why offspring are produced with the wi

  20. Q4(b)(i)

    June 2023 · AS Paper 1

    2 marksInheritance and cystic fibrosis
    The whole paper ↗
    June 2023 AS Paper 1, question 4(b)(i): Determine the probability of two individuals who are heterozygous for the Tay‑Sachs gene having a child with this condition. Use a genetic diagram, and the alle
All 60 questions on Inheritance and cystic fibrosis, as a list
  1. June 2025, Paper 3, Q3(b)(i) (1 mark): Individual T was heterozygous for this mutation. State whether this mutation is dominant or recessive. (1)
  2. June 2025, Paper 3, Q3(b)(ii) (2 marks): Scientists suggested this was a new mutation in this family originating in the genome of individual T. Explain why the scientists suggested this. (2)
  3. June 2025, AS Paper 1, Q3(a)(i) (2 marks): State what is meant by the following terms. (2) Genotype Phenotype
  4. June 2025, AS Paper 1, Q3(a)(ii) (2 marks): Explain the type of inheritance shown in this example. (2)
  5. June 2025, AS Paper 1, Q3(b)(i) (3 marks): Draw a genetic diagram to find the expected ratio of the phenotypes of the offspring. (3) Ratio of named phenotypes:
  6. June 2025, AS Paper 1, Q3(b)(ii) (1 mark): A statistical test can be used to compare observed and expected frequencies of the different phenotypes. Which statistical test is used to compare observed and
  7. June 2024, Paper 2, Q7(b)(ii) (2 marks): The diagram shows three family pedigrees. Each pedigree shows the inheritance of a different genetic condition. Only one of the pedigree diagrams definitely sho
  8. June 2024, AS Paper 1, Q2(a) (3 marks): Deduce why heterozygous snapdragon plants produce flowers with pink petals. (3)
  9. June 2024, AS Paper 1, Q2(b)(i) (3 marks): Two snapdragon plants with genotype FRFW were crossed. Determine the probability of each petal colour in the offspring of this cross, using a genetic diagram. (
  10. June 2024, AS Paper 1, Q2(b)(ii) (1 mark): There were 416 plants produced from this cross. Predict how many of these plants will have flowers with white petals. (1)
  11. June 2024, AS Paper 1, Q5(b) (2 marks): Some people have DNA polymerase that cannot detect and correct errors in DNA replication. These people have an increased risk of developing cancer. The increase
  12. June 2023, Paper 2, Q4(c) (3 marks): Genetic screening can be used to test for conditions such as cystic fibrosis. Explain why cystic fibrosis affects digestion. (3)
  13. June 2023, Paper 2, Q9(a)(i) (1 mark): The family pedigree shows the inheritance of this condition in one family. Key: = male without RP = female without RP = male with RP = female with RP It is poss
  14. June 2023, Paper 3, Q6(b)(ii) (2 marks): Deduce the pattern of inheritance of the spots and long fin phenotypes. (2)
  15. June 2023, Paper 3, Q6(c)(i) (2 marks): Complete the table by filling in the missing genotypes and phenotypes. (2) Parent 1 gametes DN Dn dN dn Genotypes and phenotypes of offspring DDNN DDNn DdNN DdN
  16. June 2023, Paper 3, Q6(c)(ii) (3 marks): The table contains the observed and expected results of this cross. Observed Expected Phenotype number number stripes and long fins 270 288 stripes and short fi
  17. June 2023, Paper 3, Q6(c)(iii) (2 marks): Some critical values for the chi squared test ( χ2) are given in the table. Critical value degrees of freedom p = 0.05 p = 0.01 1 3.84 6.64 2 5.99 9.21 3 7.82 1
  18. June 2023, AS Paper 1, Q4(a)(i) (2 marks): State what is meant by the term allele. (2)
  19. June 2023, AS Paper 1, Q4(a)(ii) (3 marks): When a round‑eyed fruit fly is crossed with a bar‑eyed fruit fly, offspring are produced that have wide bar eyes. Explain why offspring are produced with the wi
  20. June 2023, AS Paper 1, Q4(b)(i) (2 marks): Determine the probability of two individuals who are heterozygous for the Tay‑Sachs gene having a child with this condition. Use a genetic diagram, and the alle
  21. June 2022, Paper 1, Q5(b)(i) (1 mark): State the genotype and phenotype of person C. (1)
  22. June 2022, Paper 1, Q5(b)(ii) (1 mark): Person A and Person B have one son with porphyria. What was the probability of them having a child that was male and had porphyria? (1) A 0.00 B 0.25 C 0.50 D 1
  23. June 2022, Paper 2, Q9(a)(i) (2 marks): Explain how the scientists knew which allele for coat colour was recessive. (2)
  24. June 2022, Paper 2, Q9(a)(ii) (2 marks): The crosses led to a total of 1599 offspring being produced. Predict the number of yellow and non‑yellow offspring produced. (2) Offspring with a Offspring with
  25. June 2022, Paper 2, Q9(a)(iii) (3 marks): The table shows the actual number of offspring with each coat colour. Offspring with a Offspring with a yellow coat non‑yellow coat 1064 535 Explain why there a
  26. June 2022, AS Paper 1, Q5(a) (1 mark): Name another organ system that would be affected by a CFTR gene mutation. (1)
  27. June 2022, AS Paper 1, Q5(c)(i) (1 mark): Which of these individuals are heterozygous for this condition? (1) A 3 and 4 B 5 and 6 C 10 and 11 D 15 and 16
  28. June 2022, AS Paper 1, Q5(c)(ii) (1 mark): Individual 15 plans to have a child with a male who is heterozygous for the cystic fibrosis gene. Complete the Punnett square to show the possible genotypes of
  29. November 2021, Paper 1, Q6(c) (2 marks): Most cases of hereditary spherocytosis are caused by a dominant allele. Use a genetic diagram to determine the probability of a child inheriting this condition
  30. November 2021, Paper 2, Q3(c) (4 marks): Mucopolysaccharidosis type 1 (MPS 1) is a recessive genetic condition. People with MPS 1 cannot break down mucopolysaccharides. The pedigree diagram shows the i
  31. November 2021, Paper 3, Q8(f) (3 marks): Gene drives can be used to ‘force almost any genetic trait through a population’ (paragraph 16). Multiple genetic crosses were carried out between individuals h
  32. November 2021, Paper 3, Q8(l) (1 mark): Deduce the pattern of inheritance for Tay-Sachs disease (paragraph 39). (1)
  33. November 2021, AS Paper 1, Q5(a)(ii) (3 marks): The alleles that produce blood type antigens A and B are codominant. A person with the genotype IAIB has blood type AB. The allele producing blood type O is rec
  34. October 2020, Paper 3, Q2(b) (2 marks): The shell colour of the banded snail can be yellow, pink or brown. A single gene controls shell colour in the banded snail. There are three alleles for this gen
  35. October 2020, AS Paper 1, Q5(a)(i) (1 mark): Name the type of inheritance shown in this example. (1)
  36. October 2020, AS Paper 1, Q5(a)(ii) (1 mark): What is the probability of the next offspring of the same parents being roan? (1) A 25% B 50% C 75% D 100%
  37. October 2020, AS Paper 1, Q5(b)(i) (4 marks): State and justify whether alkaptonuria is caused by a recessive or a dominant allele. (4)
  38. October 2020, AS Paper 1, Q8(a) (1 mark): The CFTR gene codes for (1) A a carrier protein B a channel protein C an enzyme D a glycoprotein
  39. October 2020, AS Paper 1, Q8(b) (2 marks): A peak flow meter is used to measure the maximum rate at which air can be exhaled. This is called the peak expiratory flow (PEF). The graph shows the normal PEF
  40. October 2020, AS Paper 1, Q8(c) (3 marks): Explain the effect of a reduced PEF on gas exchange. (3)
  41. October 2020, AS Paper 1, Q8(d)(i) (1 mark): How many of the following statements are correct? ● male babies always have a larger birth weight compared to female babies ● there is a significant difference
  42. October 2020, AS Paper 1, Q8(d)(ii) (5 marks): Doctors give dietary supplements and digestive enzymes to children with cystic fibrosis. Dietary supplements include carbohydrates, proteins and lipids, as well
  43. June 2019, Paper 1, Q11(a) (2 marks): Explain what is meant by an inherited recessive disorder. (2)
  44. June 2019, Paper 1, Q11(b)(i) (1 mark): Parents without Batten disease have a child with Batten disease. Which of the following describes the genotype of the parents? (1) A bb and Bb B Bb and Bb C BB
  45. June 2019, Paper 1, Q11(b)(ii) (2 marks): Draw a genetic diagram to show the probability of their future children developing Batten disease. (2)
  46. June 2019, Paper 3, Q5(a) (3 marks): Inheritance of the weary phenotype has been investigated. Scientists crossed weary lettuce plants with upright lettuce plants. The F, generation produced from t
  47. June 2019, AS Paper 1, Q3(b)(ii) (2 marks): Two parents who are both heterozygous for the mutated allele are expecting a child. Use a genetic diagram to determine the probability of this child being homoz
  48. June 2018, AS Paper 1, Q4(a)(i) (2 marks): State what is meant by the term allele. (2)
  49. June 2018, AS Paper 1, Q4(a)(ii) (3 marks): Explain why the offspring have the palomino coat colour. (3)
  50. June 2018, AS Paper 1, Q4(b)(i) (1 mark): Deduce if achondroplasia is caused by a dominant or recessive allele. (1)
  51. June 2018, AS Paper 1, Q4(b)(ii) (3 marks): Use a genetic diagram to determine the probability that a child of parents with achondroplasia will be homozygous for this condition. (3) Answer
  52. June 2018, AS Paper 1, Q8(b) (2 marks): More than 1500 mutations have been found for the gene that codes for the production of the CFTR channel protein. Some of these mutations cause cystic fibrosis b
  53. June 2018, AS Paper 1, Q8(c)(i) (1 mark): Complete the table to show the percentage of people with each mutation. (1)
  54. June 2018, AS Paper 1, Q8(c)(ii) (2 marks): Plot a suitable graph to show the percentage of people with these mutations. (2)
  55. June 2018, AS Paper 1, Q8(d) (6 marks): The graph gives information about chloride transport in the human respiratory system with the normal allele for the CFTR protein and with the three mutated CFTR
  56. June 2017, Paper 1, Q2(c)(i) (3 marks): Describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency. (3)
  57. June 2017, Paper 1, Q10(a)(i) (1 mark): State what is meant by the term allele. (1)
  58. June 2017, Paper 2, Q3(a) (3 marks): Explain why cystic fibrosis affects the rate of oxygen uptake in the lungs. (3)
  59. June 2017, AS Paper 1, Q5(d) (6 marks): People with cystic fibrosis require a higher energy diet than people without cystic fibrosis. They are also more likely to develop problems in the pancreas. Men
  60. June 2016, AS Paper 1, Q1(a) (2 marks): A couple without Tay‑Sachs disease are expecting their second child. Their first child died from the disease. Use a genetic diagram to determine the probability

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