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DNA profiling and PCR: Edexcel A‑Level Biology A questions

Every Edexcel A-Level Biology A exam question on DNA profiling and PCR (specification points 6.3–6.4), 2016–2025, with its mark scheme and examiner’s report.

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1,749 questions

  1. Q4(a)(ii)

    June 2025 · Paper 1

    3 marksDNA profiling and PCR
    The whole paper ↗
    June 2025 Paper 1, question 4(a)(ii): There are two populations of cheetah: the Asian cheetah and the African cheetah. Describe how gel electrophoresis can be used to determine that these two popula

  2. Q6(c)

    June 2025 · Paper 3

    4 marksDNA profiling and PCR
    The whole paper ↗
    June 2025 Paper 3, question 6(c): The Rocky Mountain tailed frog is closely related to the coastal tailed frog. Devise an eDNA method that could be used to identify which of these species of fro

  3. Q1(b)(i)

    June 2023 · Paper 1

    3 marksDNA profiling and PCR
    The whole paper ↗
    June 2023 Paper 1, question 1(b)(i): Samples of DNA from this bone and bones from other Homo species can be amplified using PCR. Describe how these amplified samples of DNA can be prepared for anal

  4. Q1(b)(ii)

    June 2023 · Paper 1

    2 marksDNA profiling and PCR
    The whole paper ↗
    June 2023 Paper 1, question 1(b)(ii): Explain how the results of this analysis would show whether Homo longi is closely related to other Homo species. (2)

  5. Q2(c)

    June 2022 · Paper 3

    4 marksDNA profiling and PCR
    The whole paper ↗
    June 2022 Paper 3, question 2(c): Changes in the RNA of influenza produce new strains of the virus with an altered spike protein. Devise a procedure to determine the similarity of the strains of

  6. Q2(a)

    November 2021 · Paper 1

    1 markDNA profiling and PCR
    The whole paper ↗
    November 2021 Paper 1, question 2(a): Only small quantities of DNA can be extracted from the remains of Neanderthal humans. The quantity of extracted DNA is amplified using (1) A DNA profiling B pol

  7. Q2(b)

    November 2021 · Paper 1

    4 marksDNA profiling and PCR
    The whole paper ↗
    November 2021 Paper 1, question 2(b): Devise a procedure, using electrophoresis, to compare the amplified DNA from these two types of human. (4)

  8. Q2(c)

    November 2021 · Paper 1

    2 marksDNA profiling and PCR
    The whole paper ↗
    November 2021 Paper 1, question 2(c): Explain how the results of electrophoresis could provide evidence for interbreeding between the two types of human. (2)

  9. Q5(b)(i)

    October 2020 · Paper 3

    2 marksDNA profiling and PCR
    The whole paper ↗
    October 2020 Paper 3, question 5(b)(i): Explain the role of DNA primers in the production of the amplified 345bp sequence. (2)

  10. Q5(b)(ii)

    October 2020 · Paper 3

    3 marksDNA profiling and PCR
    The whole paper ↗
    October 2020 Paper 3, question 5(b)(ii): Explain why the amplified DNA fragments for the G20210A allele and the wild type allele are different. (3)

  11. Q5(b)(iii)

    October 2020 · Paper 3

    4 marksDNA profiling and PCR
    The whole paper ↗
    October 2020 Paper 3, question 5(b)(iii): Devise an investigation to determine the optimum number of cycles for the polymerase chain reaction used to amplify the DNA for this test. (4)

  12. Q3(b)

    June 2019 · Paper 1

    4 marksDNA profiling and PCR
    The whole paper ↗
    June 2019 Paper 1, question 3(b): Describe how DNA profiling could be carried out to show that these snakes are different species. (4)

  13. Q1(a)(i)

    June 2018 · Paper 3

    3 marksDNA profiling and PCR
    The whole paper ↗
    June 2018 Paper 3, question 1(a)(i): Describe how one PCR cycle would increase the quantity of DNA present. (3)

  14. Q1(a)(ii)

    June 2018 · Paper 3

    2 marksDNA profiling and PCR
    The whole paper ↗
    June 2018 Paper 3, question 1(a)(ii): One PCR cycle takes two minutes. Show that the quantity of DNA would have been amplified over one million times after 40 minutes. (2)

  15. Q1(b)

    June 2018 · Paper 3

    5 marksDNA profiling and PCR
    The whole paper ↗
    June 2018 Paper 3, question 1(b): The DNA produced by PCR was analysed to find out if a black panther was involved. Explain how gel electrophoresis could be used to find out if this DNA came fro
All 15 questions on DNA profiling and PCR, as a list
  1. June 2025, Paper 1, Q4(a)(ii) (3 marks): There are two populations of cheetah: the Asian cheetah and the African cheetah. Describe how gel electrophoresis can be used to determine that these two popula
  2. June 2025, Paper 3, Q6(c) (4 marks): The Rocky Mountain tailed frog is closely related to the coastal tailed frog. Devise an eDNA method that could be used to identify which of these species of fro
  3. June 2023, Paper 1, Q1(b)(i) (3 marks): Samples of DNA from this bone and bones from other Homo species can be amplified using PCR. Describe how these amplified samples of DNA can be prepared for anal
  4. June 2023, Paper 1, Q1(b)(ii) (2 marks): Explain how the results of this analysis would show whether Homo longi is closely related to other Homo species. (2)
  5. June 2022, Paper 3, Q2(c) (4 marks): Changes in the RNA of influenza produce new strains of the virus with an altered spike protein. Devise a procedure to determine the similarity of the strains of
  6. November 2021, Paper 1, Q2(a) (1 mark): Only small quantities of DNA can be extracted from the remains of Neanderthal humans. The quantity of extracted DNA is amplified using (1) A DNA profiling B pol
  7. November 2021, Paper 1, Q2(b) (4 marks): Devise a procedure, using electrophoresis, to compare the amplified DNA from these two types of human. (4)
  8. November 2021, Paper 1, Q2(c) (2 marks): Explain how the results of electrophoresis could provide evidence for interbreeding between the two types of human. (2)
  9. October 2020, Paper 3, Q5(b)(i) (2 marks): Explain the role of DNA primers in the production of the amplified 345bp sequence. (2)
  10. October 2020, Paper 3, Q5(b)(ii) (3 marks): Explain why the amplified DNA fragments for the G20210A allele and the wild type allele are different. (3)
  11. October 2020, Paper 3, Q5(b)(iii) (4 marks): Devise an investigation to determine the optimum number of cycles for the polymerase chain reaction used to amplify the DNA for this test. (4)
  12. June 2019, Paper 1, Q3(b) (4 marks): Describe how DNA profiling could be carried out to show that these snakes are different species. (4)
  13. June 2018, Paper 3, Q1(a)(i) (3 marks): Describe how one PCR cycle would increase the quantity of DNA present. (3)
  14. June 2018, Paper 3, Q1(a)(ii) (2 marks): One PCR cycle takes two minutes. Show that the quantity of DNA would have been amplified over one million times after 40 minutes. (2)
  15. June 2018, Paper 3, Q1(b) (5 marks): The DNA produced by PCR was analysed to find out if a black panther was involved. Explain how gel electrophoresis could be used to find out if this DNA came fro

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