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Amino acids, proteins and DNA: AQA A‑Level Chemistry questions

Every AQA A-Level Chemistry exam question on 3.3.13 Amino acids, proteins and DNA, 2016–2025, with its mark scheme and examiner’s report.

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2,301 questions

  1. Q06.2

    June 2025 · Paper 2

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2025 Paper 2, question 06.2: Use Figure 6 to determine the structure of the amino acid histidine, His [1 mark]

  2. Q06.3

    June 2025 · Paper 2

    2 marks3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2025 Paper 2, question 06.3: Increasing the temperature of an alkaline solution of poly(lysine) changes the type of secondary structure in poly(lysine), as shown. Name the type of secondary

  3. Q29

    June 2025 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2025 Paper 3, question 29: What is the structure of a dipeptide formed from the two amino acids shown? [1 mark] A B C D

  4. Q33

    June 2025 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2025 Paper 3, question 33: The diagram shows part of the tertiary structure for a protein. Some of the amino acids in this structure are shown using the first three letters of their names

  5. Q34

    June 2025 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2025 Paper 3, question 34: Which statement about enzymes is correct? [1 mark] A Enzymes are a type of nucleotide. B Enzymes are polymers. C Enzymes are not affected by changes of pH. D En

  6. Q33

    June 2024 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2024 Paper 3, question 33: Which structure shows a zwitterion of an amino acid? [1 mark] A B C D

  7. Q35

    June 2024 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2024 Paper 3, question 35: Which structure is formed by phenylalanine in solution at pH = 3? [1 mark] A B C D

  8. Q03.1

    June 2023 · Paper 3

    2 marks3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2023 Paper 3, question 03.1: The –NH2 at the end of the amino acid sequence of endomorphin-2 shows that the terminal functional group is an amide, not an acid. Complete the structure of end

  9. Q03.2

    June 2023 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2023 Paper 3, question 03.2: Use the structure in Figure 2 to draw the skeletal formula of proline, Pro. [1 mark]

  10. Q03.3

    June 2023 · Paper 3

    2 marks3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2023 Paper 3, question 03.3: State a reagent and the conditions needed for the hydrolysis. [2 marks] Reagent Conditions

  11. Q35

    June 2023 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2023 Paper 3, question 35: Which statement about enzymes is not correct? [1 mark] A The tertiary structure of an enzyme influences which molecules can bind to the active site. B The actio

  12. Q04.1

    June 2022 · Paper 2

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 2, question 04.1: Identify the type of protein structure shown. [1 mark] Tick () one box. Primary Secondary Tertiary

  13. Q04.2

    June 2022 · Paper 2

    2 marks3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 2, question 04.2: Draw a structure for the –Cys–Ser– section of the protein. Use the Data Booklet to help you answer this question. [2 marks]

  14. Q04.3

    June 2022 · Paper 2

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 2, question 04.3: Name the other substance formed when two amino acids react together to form part of a protein chain. [1 mark]

  15. Q04.4

    June 2022 · Paper 2

    4 marks3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 2, question 04.4: Explain why the strength of the interaction between two cysteine R groups differs from the strength of the interaction between a serine R group and an aspartic

  16. Q04.5

    June 2022 · Paper 2

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 2, question 04.5: Deduce the type of interaction that occurs between a lysine R group and an aspartic acid R group. [1 mark]

  17. Q29

    June 2022 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 3, question 29: Which is the main species present in an aqueous solution of aspartic acid at pH = 14? [1 mark] A B C D

  18. Q32

    June 2022 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 3, question 32: Which type of interaction between polypeptide chains is mainly responsible for maintaining the secondary structure of a protein in the form of an alpha helix? [

  19. Q33

    June 2022 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 3, question 33: Which statement about HOCH2CH(NH2)COOH is correct? [1 mark] A It decolourises bromine water. B It is a component of DNA. C It is insoluble in water. D It reacts

  20. Q35

    June 2022 · Paper 3

    1 mark3.3.13 Amino acids, proteins and DNA
    The whole paper ↗
    June 2022 Paper 3, question 35: Which compound is not a 2-aminocarboxylic acid? [1 mark] A CH3CH(NH2)COOH B CH3CH(NH2)CH2COOH C CH3CH2CH(NH2)COOH D (CH3)2CHCH(NH2)COOH
All 55 questions on Amino acids, proteins and DNA, as a list
  1. June 2025, Paper 2, Q06.2 (1 mark): Use Figure 6 to determine the structure of the amino acid histidine, His [1 mark]
  2. June 2025, Paper 2, Q06.3 (2 marks): Increasing the temperature of an alkaline solution of poly(lysine) changes the type of secondary structure in poly(lysine), as shown. Name the type of secondary
  3. June 2025, Paper 3, Q29 (1 mark): What is the structure of a dipeptide formed from the two amino acids shown? [1 mark] A B C D
  4. June 2025, Paper 3, Q33 (1 mark): The diagram shows part of the tertiary structure for a protein. Some of the amino acids in this structure are shown using the first three letters of their names
  5. June 2025, Paper 3, Q34 (1 mark): Which statement about enzymes is correct? [1 mark] A Enzymes are a type of nucleotide. B Enzymes are polymers. C Enzymes are not affected by changes of pH. D En
  6. June 2024, Paper 3, Q33 (1 mark): Which structure shows a zwitterion of an amino acid? [1 mark] A B C D
  7. June 2024, Paper 3, Q35 (1 mark): Which structure is formed by phenylalanine in solution at pH = 3? [1 mark] A B C D
  8. June 2023, Paper 3, Q03.1 (2 marks): The –NH2 at the end of the amino acid sequence of endomorphin-2 shows that the terminal functional group is an amide, not an acid. Complete the structure of end
  9. June 2023, Paper 3, Q03.2 (1 mark): Use the structure in Figure 2 to draw the skeletal formula of proline, Pro. [1 mark]
  10. June 2023, Paper 3, Q03.3 (2 marks): State a reagent and the conditions needed for the hydrolysis. [2 marks] Reagent Conditions
  11. June 2023, Paper 3, Q35 (1 mark): Which statement about enzymes is not correct? [1 mark] A The tertiary structure of an enzyme influences which molecules can bind to the active site. B The actio
  12. June 2022, Paper 2, Q04.1 (1 mark): Identify the type of protein structure shown. [1 mark] Tick () one box. Primary Secondary Tertiary
  13. June 2022, Paper 2, Q04.2 (2 marks): Draw a structure for the –Cys–Ser– section of the protein. Use the Data Booklet to help you answer this question. [2 marks]
  14. June 2022, Paper 2, Q04.3 (1 mark): Name the other substance formed when two amino acids react together to form part of a protein chain. [1 mark]
  15. June 2022, Paper 2, Q04.4 (4 marks): Explain why the strength of the interaction between two cysteine R groups differs from the strength of the interaction between a serine R group and an aspartic
  16. June 2022, Paper 2, Q04.5 (1 mark): Deduce the type of interaction that occurs between a lysine R group and an aspartic acid R group. [1 mark]
  17. June 2022, Paper 3, Q29 (1 mark): Which is the main species present in an aqueous solution of aspartic acid at pH = 14? [1 mark] A B C D
  18. June 2022, Paper 3, Q32 (1 mark): Which type of interaction between polypeptide chains is mainly responsible for maintaining the secondary structure of a protein in the form of an alpha helix? [
  19. June 2022, Paper 3, Q33 (1 mark): Which statement about HOCH2CH(NH2)COOH is correct? [1 mark] A It decolourises bromine water. B It is a component of DNA. C It is insoluble in water. D It reacts
  20. June 2022, Paper 3, Q35 (1 mark): Which compound is not a 2-aminocarboxylic acid? [1 mark] A CH3CH(NH2)COOH B CH3CH(NH2)CH2COOH C CH3CH2CH(NH2)COOH D (CH3)2CHCH(NH2)COOH
  21. November 2021, Paper 3, Q35 (1 mark): Which is the structure of a zwitterion of an amino acid? [1 mark] A B C D
  22. November 2021, Paper 3, Q36 (1 mark): Which row shows a pair of bases that can link two strands of DNA with three hydrogen bonds? Use the Data Booklet to help you answer this question. [1 mark] Base
  23. November 2020, Paper 2, Q02.4 (2 marks): Figure 4 shows optical isomers F and G. Figure 4 Isomer F is the active compound in the medicine ibuprofen. In the manufacture of ibuprofen both isomers F and G
  24. November 2020, Paper 3, Q30 (1 mark): Which structure shows the zwitterion of an amino acid? [1 mark] A B C D
  25. June 2019, Paper 2, Q09.1 (1 mark): Suggest a suitable reagent for the hydrolysis of a protein. [1 mark]
  26. June 2019, Paper 2, Q12.1 (2 marks): Draw all the hydrogen bonds between the complementary strands shown in Figure 4. Use dashed lines to show the hydrogen bonds. You do not need to show lone pairs
  27. June 2019, Paper 2, Q12.2 (2 marks): Draw a ring around each of the component parts that make up the cytosine nucleotide in the section of DNA shown in Figure 4. [2 marks]
  28. June 2019, Paper 2, Q12.3 (1 mark): State the meaning of the term complementary when it is used to refer to DNA strands. [1 mark]
  29. June 2019, Paper 3, Q29 (1 mark): Which structure shows part of a peptide link in a protein? [1 mark] A B C D
  30. June 2019, Paper 3, Q30 (1 mark): Two strands of DNA are linked together by hydrogen bonding between bases on each strand. Which row shows the number of hydrogen bonds between the pair of bases?
  31. June 2019, Paper 3, Q35 (1 mark): Use the Data Booklet to help you answer this question Which is the main aspartic acid species present in an aqueous solution at pH = 14? [1 mark] A B C D
  32. June 2018, Paper 2, Q08.1 (2 marks): The polypeptide chains are held together by hydrogen bonding as shown in Figure 1. Explain how these hydrogen bonds form. [2 marks]
  33. June 2018, Paper 2, Q08.2 (1 mark): A different type of bond can form between two polypeptide chains when the chains each contain the amino acid cysteine. Complete the structure to show the bond t
  34. June 2018, Paper 2, Q08.3 (1 mark): The type of bond in Question 08.2 between two polypeptide chains influences the three-dimensional structure of the protein. Name this type of protein structure.
  35. June 2018, Paper 2, Q08.4 (2 marks): Draw the structure of the zwitterion of a dipeptide formed by alanine and serine. [2 marks]
  36. June 2018, Paper 2, Q09.1 (1 mark): Complete Table 4 to show the correct sequence of bases in the complementary strand represented by the numbers 1 to 5 [1 mark] Table 4 1 2 3 4 5
  37. June 2018, Paper 2, Q09.2 (1 mark): Deduce the total number of hydrogen bonds formed between the five bases in each strand. Tick () one box. [1 mark] 10 12 13 15
  38. June 2018, Paper 2, Q09.3 (2 marks): Base A is part of a nucleotide in the DNA strand shown in Figure 2. A nucleotide contains a 2-deoxyribose molecule. An incomplete 2-deoxyribose molecule is show
  39. June 2018, Paper 3, Q15 (1 mark): Which structure is formed by aspartic acid in solution at pH 12? [1 mark] A B C D
  40. June 2017, Paper 2, Q06.1 (1 mark): Draw the structure of the zwitterion formed by phenylalanine. [1 mark
  41. June 2017, Paper 2, Q06.2 (1 mark): Draw the structure of serine at high pH. [1 mark
  42. June 2017, Paper 2, Q06.3 (2 marks): Draw the structures of both dipeptides formed when phenylalanine reacts with serine. In each structure show all the atoms and bonds in the amide link. [2 marks
  43. June 2017, Paper 2, Q09.1 (2 marks): A deoxyribose molecule in a strand of DNA is shown. Name the types of group attached to 2-deoxyribose at positions X and Y. [2 marks X Y
  44. June 2017, Paper 2, Q09.2 (2 marks): In the DNA double helix, adenine is linked by hydrogen bonds to a molecule in the other strand of DNA. Complete the diagram below to show the other molecule and
  45. Specimen, Paper 2, Q05.1 (1 mark): 5 Figure 3 shows a simplified representation of the arrangement of some amino acids in a portion of a protein structure in the form of an α-helix. Figure 3 Name
  46. Specimen, Paper 2, Q05.2 (4 marks): 5
  47. Specimen, Paper 2, Q06.1 (1 mark): 6 The tripeptide shown in Figure 4 is formed from the amino acids glycine, threonine and lysine. Figure 4 H2N C H H C O N H C CHOH H C CH3 O N H C (CH2)4 H COOH
  48. Specimen, Paper 2, Q06.2 (1 mark): Draw the zwitterion of glycine. [1 mark] 0 6 . 2
  49. Specimen, Paper 2, Q06.4 (1 mark): Deduce the IUPAC name of threonine. [1 mark] 0 6 . 4
  50. Specimen, Paper 2, Q06.5 (1 mark): 6
  51. Specimen, Paper 2, Q08.1 (1 mark): 9
  52. Specimen, Paper 2, Q08.2 (4 marks): 0
  53. Specimen, Paper 2, Q08.3 (1 mark): Cisplatin works because one of the atoms on guanine can form a co-ordinate bond with platinum, replacing one of the ammonia or chloride ligands. Another atom on
  54. Specimen, Paper 2, Q08.4 (1 mark): Figure 8 NH2 NHCOCH3 NHCOCH3 Step 1 Step 2 NO2 Step 3 NH2 NO2 NH2 NH2 Step 4 9 1,4-diaminobenzene is an important intermediate in the production of polymers suc
  55. Specimen, Paper 3, Q32: 3

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