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Hardy-Weinberg and classification: Edexcel A‑Level Biology A questions

Every Edexcel A-Level Biology A exam question on Hardy-Weinberg and classification (specification points 4.5–4.6), 2016–2025, with its mark scheme and examiner’s report.

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1,749 questions

  1. Q4(a)(i)

    June 2025 · Paper 1

    1 markHardy-Weinberg and classification
    The whole paper ↗
    June 2025 Paper 1, question 4(a)(i): Which of the following defines the term species? (1) A a group of different organisms that live in the same habitat B a group of organisms that live in the same

  2. Q2(a)(ii)

    June 2025 · Paper 3

    1 markHardy-Weinberg and classification
    The whole paper ↗
    June 2025 Paper 3, question 2(a)(ii): Give the domain to which Stentor coeruleus belongs. (1)

  3. Q4(a)

    June 2025 · AS Paper 2

    2 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2025 AS Paper 2, question 4(a): State what is meant by the term species. (2)

  4. Q7(b)(i)

    June 2024 · Paper 1

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2024 Paper 1, question 7(b)(i): The colour of the coats of deer is controlled by a single gene. The allele for brown coats is dominant and the allele for white coats is recessive. Calculate th

  5. Q8(a)

    June 2024 · Paper 3

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2024 Paper 3, question 8(a): Explain why analysis of the amino acid sequence of the eye lens proteins can be used to determine the phylogenetic relationship of different sloths (Box 1). (3)

  6. Q8(b)

    June 2024 · Paper 3

    4 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2024 Paper 3, question 8(b): Describe how the algae living on the hair of sloths can be shown to belong to one of four phyla (Box 2). (4)

  7. Q5(a)(i)

    June 2024 · AS Paper 2

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2024 AS Paper 2, question 5(a)(i): Use the Hardy–Weinberg equation to calculate the number of birds in this group that would have the dominant phenotype. (3) p2 + 2pq + q2 = 1 Answer

  8. Q5(a)(ii)

    June 2024 · AS Paper 2

    1 markHardy-Weinberg and classification
    The whole paper ↗
    June 2024 AS Paper 2, question 5(a)(ii): If only 20 birds were released, the Hardy–Weinberg equilibrium would change over time. How many of the following statements could cause a change in this equilib

  9. Q3(a)(i)

    June 2023 · AS Paper 2

    1 markHardy-Weinberg and classification
    The whole paper ↗
    June 2023 AS Paper 2, question 3(a)(i): Which part of the equation shows the proportion of heterozygotes in a population? (1) A p2 B 2pq C q2 D 1

  10. Q3(a)(ii)

    June 2023 · AS Paper 2

    1 markHardy-Weinberg and classification
    The whole paper ↗
    June 2023 AS Paper 2, question 3(a)(ii): Which is the value for q2 if p2 = 0.49? (1) A 0.09 B 0.30 C 0.51 D 0.70

  11. Q3(b)(i)

    June 2023 · AS Paper 2

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2023 AS Paper 2, question 3(b)(i): Use the Hardy–Weinberg equation to calculate the number of hedgehogs in this population that are heterozygous for the blonde allele. p2 + 2pq + q2 = 1.0 (3) Ans

  12. Q7(a)(ii)

    June 2023 · AS Paper 2

    2 marksHardy-Weinberg and classification
    The whole paper ↗
    June 2023 AS Paper 2, question 7(a)(ii): Scientists tested the RNA of these microorganisms and discovered that they belonged to the domain Archaea. Explain how molecular phylogeny could be used to iden

  13. Q3(a)

    November 2021 · Paper 1

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    November 2021 Paper 1, question 3(a): The presence of tusks is controlled by a single gene. The allele for tusks is known to be dominant. The frequency of alleles in a population can be determined u

  14. Q3(b)(ii)

    November 2021 · Paper 1

    2 marksHardy-Weinberg and classification
    The whole paper ↗
    November 2021 Paper 1, question 3(b)(ii): Describe how the Hardy‑Weinberg equation can be used to provide evidence for changes in the elephant population in Mozambique. (2)

  15. Q1(a)

    November 2021 · Paper 2

    2 marksHardy-Weinberg and classification
    The whole paper ↗
    November 2021 Paper 2, question 1(a): Complete the table to show the features in Bacteria and in Eukaryota. (2)

  16. Q1(b)

    November 2021 · Paper 2

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    November 2021 Paper 2, question 1(b): Explain how the information in the table can be used to show that the Archaea are more closely related to the Eukaryota than to the Bacteria. (3)

  17. Q8(a)

    November 2021 · Paper 3

    2 marksHardy-Weinberg and classification
    The whole paper ↗
    November 2021 Paper 3, question 8(a): Explain how two populations of mosquito could be shown to belong to different species (paragraph 4). (2)

  18. Q8(c)

    November 2021 · AS Paper 2

    6 marksHardy-Weinberg and classificationBiodiversity, adaptation and natural selection
    The whole paper ↗
    November 2021 AS Paper 2, question 8(c): The graph shows the changes in the relative abundance of pollinating wild bee species in the UK. The original sample in 1980 represents a value of 100%. 110 100

  19. Q8(c)(i)

    October 2020 · Paper 2

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    October 2020 Paper 2, question 8(c)(i): Calculate the number of people in the UK who are carriers of LGMD2A using the Hardy-Weinberg equation. (3) p2 + 2pq + q2 = 1 Answer

  20. Q8(c)(ii)

    October 2020 · Paper 2

    3 marksHardy-Weinberg and classification
    The whole paper ↗
    October 2020 Paper 2, question 8(c)(ii): In the human population, the frequency of the allele for LGMD2A may change from one generation to the next. Explain why the frequency of this allele may change
All 42 questions on Hardy-Weinberg and classification, as a list
  1. June 2025, Paper 1, Q4(a)(i) (1 mark): Which of the following defines the term species? (1) A a group of different organisms that live in the same habitat B a group of organisms that live in the same
  2. June 2025, Paper 3, Q2(a)(ii) (1 mark): Give the domain to which Stentor coeruleus belongs. (1)
  3. June 2025, AS Paper 2, Q4(a) (2 marks): State what is meant by the term species. (2)
  4. June 2024, Paper 1, Q7(b)(i) (3 marks): The colour of the coats of deer is controlled by a single gene. The allele for brown coats is dominant and the allele for white coats is recessive. Calculate th
  5. June 2024, Paper 3, Q8(a) (3 marks): Explain why analysis of the amino acid sequence of the eye lens proteins can be used to determine the phylogenetic relationship of different sloths (Box 1). (3)
  6. June 2024, Paper 3, Q8(b) (4 marks): Describe how the algae living on the hair of sloths can be shown to belong to one of four phyla (Box 2). (4)
  7. June 2024, AS Paper 2, Q5(a)(i) (3 marks): Use the Hardy–Weinberg equation to calculate the number of birds in this group that would have the dominant phenotype. (3) p2 + 2pq + q2 = 1 Answer
  8. June 2024, AS Paper 2, Q5(a)(ii) (1 mark): If only 20 birds were released, the Hardy–Weinberg equilibrium would change over time. How many of the following statements could cause a change in this equilib
  9. June 2023, AS Paper 2, Q3(a)(i) (1 mark): Which part of the equation shows the proportion of heterozygotes in a population? (1) A p2 B 2pq C q2 D 1
  10. June 2023, AS Paper 2, Q3(a)(ii) (1 mark): Which is the value for q2 if p2 = 0.49? (1) A 0.09 B 0.30 C 0.51 D 0.70
  11. June 2023, AS Paper 2, Q3(b)(i) (3 marks): Use the Hardy–Weinberg equation to calculate the number of hedgehogs in this population that are heterozygous for the blonde allele. p2 + 2pq + q2 = 1.0 (3) Ans
  12. June 2023, AS Paper 2, Q7(a)(ii) (2 marks): Scientists tested the RNA of these microorganisms and discovered that they belonged to the domain Archaea. Explain how molecular phylogeny could be used to iden
  13. November 2021, Paper 1, Q3(a) (3 marks): The presence of tusks is controlled by a single gene. The allele for tusks is known to be dominant. The frequency of alleles in a population can be determined u
  14. November 2021, Paper 1, Q3(b)(ii) (2 marks): Describe how the Hardy‑Weinberg equation can be used to provide evidence for changes in the elephant population in Mozambique. (2)
  15. November 2021, Paper 2, Q1(a) (2 marks): Complete the table to show the features in Bacteria and in Eukaryota. (2)
  16. November 2021, Paper 2, Q1(b) (3 marks): Explain how the information in the table can be used to show that the Archaea are more closely related to the Eukaryota than to the Bacteria. (3)
  17. November 2021, Paper 3, Q8(a) (2 marks): Explain how two populations of mosquito could be shown to belong to different species (paragraph 4). (2)
  18. November 2021, AS Paper 2, Q8(c) (6 marks): The graph shows the changes in the relative abundance of pollinating wild bee species in the UK. The original sample in 1980 represents a value of 100%. 110 100
  19. October 2020, Paper 2, Q8(c)(i) (3 marks): Calculate the number of people in the UK who are carriers of LGMD2A using the Hardy-Weinberg equation. (3) p2 + 2pq + q2 = 1 Answer
  20. October 2020, Paper 2, Q8(c)(ii) (3 marks): In the human population, the frequency of the allele for LGMD2A may change from one generation to the next. Explain why the frequency of this allele may change
  21. October 2020, Paper 3, Q5(a)(ii) (3 marks): The frequency of the G20210A allele in a population of 10 000 individuals was investigated. In this population, 50 individuals were homozygous for G20210A. Calc
  22. October 2020, AS Paper 2, Q5(a) (1 mark): The pairing that would be expected to be able to mate and produce fertile offspring is (1) A Asian badger and South Asian badger B Eurasian badger and Asian bad
  23. October 2020, AS Paper 2, Q5(b)(i) (3 marks): Explain how molecular phylogeny can be used to show that these two populations are reproductively isolated. (3)
  24. October 2020, AS Paper 2, Q5(b)(ii) (4 marks): Describe how mutations in badgers to the east of the Bosphorus Strait may lead to this population becoming a separate species. (4)
  25. October 2020, AS Paper 2, Q5(c) (2 marks): Explain how the Hardy-Weinberg equation can be used to show that natural selection is occurring in a population. (2)
  26. June 2019, Paper 1, Q3(a) (1 mark): State what is meant by the term species. (1)
  27. June 2019, Paper 2, Q3(a) (3 marks): Use the Hardy-Weinberg equation to calculate the probability of babies born in the UK being carriers for cystic fibrosis. (3) Answer
  28. June 2019, AS Paper 2, Q2(a) (1 mark): The two squirrels are classified as different species because they (1) A are geographically isolated B cannot produce fertile offspring C have different coloure
  29. June 2019, AS Paper 2, Q2(b)(ii) (1 mark): The red squirrels on Brownsea Island are geographically isolated from other red squirrel populations on the UK mainland. Over time, the Brownsea Island populati
  30. June 2019, AS Paper 2, Q2(c)(i) (1 mark): Woese classified organisms into domains. Which of the following contain prokaryotic organisms? (1) A Archaea, Bacteria and Eukaryota B only Archaea C only Archa
  31. June 2019, AS Paper 2, Q8(a) (3 marks): Calculate the number of carriers in a population of 17.02 million. Use the Hardy-Weinberg equation, p2 + 2pq + q2 = 1 (3) Answer
  32. June 2019, AS Paper 2, Q8(b)(ii) (2 marks): Explain why the genotype frequency for males with DMD cannot be calculated using this Hardy-Weinberg equation. (2)
  33. June 2018, Paper 1, Q7(a) (1 mark): The electron micrograph shows a section through a fungal cell. Magnification ×1000 To which group do fungi belong? (1) A Archaea B Eukaryota C Prokaryota D Viru
  34. June 2018, Paper 1, Q8(b) (3 marks): The primary structures of trypsin molecules from different species have been used to produce a phylogenetic tree for trypsin. Each branch of the following phylo
  35. June 2018, AS Paper 2, Q6(c)(i) (2 marks): Explain how this diagram indicates that saiga antelopes are more closely related to Antilope than to Antidorcas. (2)
  36. June 2018, AS Paper 2, Q6(c)(ii) (3 marks): This is a more recent classification diagram based on a study of the mitochondrial genomes of antelopes. Gazella Nanger Eudorcas Antilope Litocranius Antidorcas
  37. June 2018, AS Paper 2, Q8(b)(i) (2 marks): Explain why they are now classed as different species. (2)
  38. June 2018, AS Paper 2, Q8(c) (6 marks): The map shows the distribution of two species of sloth. There are currently two major populations of C. hoffmanni in South America. B. pygmaeus is restricted to
  39. June 2017, Paper 1, Q10(a)(ii) (3 marks): Use the Hardy-Weinberg equation to show that more than 50% of the forest elephant population are homozygous for the GBA gene. (3) Answer
  40. June 2017, Paper 1, Q10(b)(i) (6 marks): Analyse the data and the information provided to comment on the validity of this conclusion. (6)
  41. June 2017, AS Paper 2, Q3(b) (2 marks): Explain how molecular phylogeny could be used to determine the relationships between the Scottish wildcat and other subspecies of European wildcat. (2)
  42. June 2017, AS Paper 2, Q4(b)(ii) (3 marks): People with a heterozygous genotype for this condition do not develop severe sickle cell anaemia. The Yoruba are a group of people who live in West Africa. In a

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