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Chemical elements are joined together to form biological compounds: WJEC A‑Level Biology questions

Every WJEC A-Level Biology exam question on 1.1 Chemical elements are joined together to form biological compounds, 2016–2025, with its mark scheme and examiner’s report.

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1,223 questions

  1. Q2(b)(i)

    Summer 2025 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 2(b)(i): State the highest level of protein structure shown by proinsulin in Image 2.2. [1]

  2. Q3(a)

    Summer 2025 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 3(a): Image 3.1a shows a molecule of alpha glucose and Image 3.1b shows a molecule of glucose-1-phosphate. Image 3.1a Image 3.1b CH2OH CH2OH O O H H H H H H O OH OH H

  3. Q3(c)

    Summer 2025 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 3(c): Describe a biochemical test the student could use to show that glucose-1-phosphate is a reducing sugar. [2]

  4. Q5(a)(i)

    Summer 2025 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 5(a)(i): Draw a circle around the R-group of each amino acid. [1]

  5. Q5(a)(ii)

    Summer 2025 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 5(a)(ii): These two amino acids can be joined together during a chemical reaction. State the type of reaction and name the bond formed when these two amino acids are join

  6. Q6(a)

    Summer 2025 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2025 AS Unit 1, question 6(a): State one similarity and one difference between the structure of a triglyceride and the structure of a phospholipid. [2] Similarity: . . . . . . . . . . . . . .

  7. Q2(a)(iii)

    Summer 2024 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 2(a)(iii): Name two inorganic ions needed by plant cells in order to synthesise the molecules shown in Image 2.1. [1]

  8. Q4(a)(i)

    Summer 2024 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(a)(i): State what is meant by the term structural isomer. [1]

  9. Q4(a)(ii)

    Summer 2024 · AS Unit 1

    6 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(a)(ii): Complete Table 4.2 to describe the structure and function of the polysaccharides A and B, found in plants. [6] Table 4.2 Polysaccharide A Polysaccharide B Name

  10. Q4(a)(iii)

    Summer 2024 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(a)(iii): Polysaccharide A is hydrolysed by an enzyme which results in production of the disaccharide shown in Image 4.3. Image 4.3 CH2OH CH2OH O O H H H H H H OH H OH H

  11. Q4(b)

    Summer 2024 · AS Unit 1

    3 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(b): Gentiobiose, shown in Image 4.4, is a disaccharide which consists of two glucose monomers joined by a β-1,6-glycosidic bond. Image 4.4 CH2OH 6 β -1,6-glycosidic

  12. Q4(c)(i)

    Summer 2024 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(c)(i): Annotate Image 4.5, to show the polarity of a water molecule. [1]

  13. Q4(c)(ii)

    Summer 2024 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(c)(ii): With reference to Images 4.3, 4.4 and 4.5, explain why monosaccharides and disaccharides are soluble in water. [1]

  14. Q4(c)(iii)

    Summer 2024 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 4(c)(iii): State why it is important to plants that sugars are soluble. [2]

  15. Q6(b)(i)

    Summer 2024 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2024 AS Unit 1, question 6(b)(i): Use the information provided to state the highest level of protein structure shown by the microtubule in Image 6.2. Explain your answer. [2]

  16. Q1(a)(i)

    Summer 2023 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2023 AS Unit 1, question 1(a)(i): State what is meant by primary structure. [1]

  17. Q1(a)(ii)

    Summer 2023 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2023 AS Unit 1, question 1(a)(ii): Use the information given and your own knowledge to complete Table 1.2 to explain how the secondary and tertiary structures of lysozyme are illustrated in Image

  18. Q4(a)(i)

    Summer 2023 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2023 AS Unit 1, question 4(a)(i): State the general name given to bonds X and Y. [1]

  19. Q4(a)(ii)

    Summer 2023 · AS Unit 1

    2 marks1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2023 AS Unit 1, question 4(a)(ii): State one similarity and one difference between amylose and amylopectin, shown in Images 4.1 and 4.2. [2] Similarity Difference

  20. Q4(b)(i)

    Summer 2023 · AS Unit 1

    1 mark1.1 Chemical elements are joined together to form biological compounds
    The whole paper ↗
    Summer 2023 AS Unit 1, question 4(b)(i): State what is meant by the term hydrolysis. [1] Amylopectin is digested in a similar way but needs an additional enzyme, isomaltase, for complete hydrolysis.
All 54 questions on Chemical elements are joined together to form biological compounds, as a list
  1. Summer 2025, AS Unit 1, Q2(b)(i) (1 mark): State the highest level of protein structure shown by proinsulin in Image 2.2. [1]
  2. Summer 2025, AS Unit 1, Q3(a) (1 mark): Image 3.1a shows a molecule of alpha glucose and Image 3.1b shows a molecule of glucose-1-phosphate. Image 3.1a Image 3.1b CH2OH CH2OH O O H H H H H H O OH OH H
  3. Summer 2025, AS Unit 1, Q3(c) (2 marks): Describe a biochemical test the student could use to show that glucose-1-phosphate is a reducing sugar. [2]
  4. Summer 2025, AS Unit 1, Q5(a)(i) (1 mark): Draw a circle around the R-group of each amino acid. [1]
  5. Summer 2025, AS Unit 1, Q5(a)(ii) (2 marks): These two amino acids can be joined together during a chemical reaction. State the type of reaction and name the bond formed when these two amino acids are join
  6. Summer 2025, AS Unit 1, Q6(a) (2 marks): State one similarity and one difference between the structure of a triglyceride and the structure of a phospholipid. [2] Similarity: . . . . . . . . . . . . . .
  7. Summer 2024, AS Unit 1, Q2(a)(iii) (1 mark): Name two inorganic ions needed by plant cells in order to synthesise the molecules shown in Image 2.1. [1]
  8. Summer 2024, AS Unit 1, Q4(a)(i) (1 mark): State what is meant by the term structural isomer. [1]
  9. Summer 2024, AS Unit 1, Q4(a)(ii) (6 marks): Complete Table 4.2 to describe the structure and function of the polysaccharides A and B, found in plants. [6] Table 4.2 Polysaccharide A Polysaccharide B Name
  10. Summer 2024, AS Unit 1, Q4(a)(iii) (2 marks): Polysaccharide A is hydrolysed by an enzyme which results in production of the disaccharide shown in Image 4.3. Image 4.3 CH2OH CH2OH O O H H H H H H OH H OH H
  11. Summer 2024, AS Unit 1, Q4(b) (3 marks): Gentiobiose, shown in Image 4.4, is a disaccharide which consists of two glucose monomers joined by a β-1,6-glycosidic bond. Image 4.4 CH2OH 6 β -1,6-glycosidic
  12. Summer 2024, AS Unit 1, Q4(c)(i) (1 mark): Annotate Image 4.5, to show the polarity of a water molecule. [1]
  13. Summer 2024, AS Unit 1, Q4(c)(ii) (1 mark): With reference to Images 4.3, 4.4 and 4.5, explain why monosaccharides and disaccharides are soluble in water. [1]
  14. Summer 2024, AS Unit 1, Q4(c)(iii) (2 marks): State why it is important to plants that sugars are soluble. [2]
  15. Summer 2024, AS Unit 1, Q6(b)(i) (2 marks): Use the information provided to state the highest level of protein structure shown by the microtubule in Image 6.2. Explain your answer. [2]
  16. Summer 2023, AS Unit 1, Q1(a)(i) (1 mark): State what is meant by primary structure. [1]
  17. Summer 2023, AS Unit 1, Q1(a)(ii) (2 marks): Use the information given and your own knowledge to complete Table 1.2 to explain how the secondary and tertiary structures of lysozyme are illustrated in Image
  18. Summer 2023, AS Unit 1, Q4(a)(i) (1 mark): State the general name given to bonds X and Y. [1]
  19. Summer 2023, AS Unit 1, Q4(a)(ii) (2 marks): State one similarity and one difference between amylose and amylopectin, shown in Images 4.1 and 4.2. [2] Similarity Difference
  20. Summer 2023, AS Unit 1, Q4(b)(i) (1 mark): State what is meant by the term hydrolysis. [1] Amylopectin is digested in a similar way but needs an additional enzyme, isomaltase, for complete hydrolysis.
  21. Summer 2023, AS Unit 1, Q4(b)(ii) (3 marks): Explain the roles of the three enzymes involved in the complete hydrolysis of starch. [3]
  22. Summer 2023, AS Unit 1, Q4(b)(iii) (2 marks): One variety of corn used in animal feed has a lower amylose : amylopectin ratio than other varieties. With reference to Images 4.2 and 4.3, suggest why this low
  23. Summer 2023, AS Unit 1, Q4(b)(iv) (2 marks): Describe a chemical test that could be used to show that starch is no longer present at the end of hydrolysis. [2]
  24. Summer 2022, AS Unit 1, Q2(a)(i) (2 marks): Structures A and B are both types of fatty acids. Identify both types and explain the difference in their shapes. [2]
  25. Summer 2022, AS Unit 1, Q2(a)(ii) (2 marks): Image 2.2 shows two examples of phospholipid bilayers. Membrane 1 has phospholipids containing only type A fatty acids and membrane 2 has phospholipids containi
  26. Summer 2022, AS Unit 1, Q2(b)(i) (2 marks): Fatty acids are also found as part of triglycerides. State how triglycerides differ from phospholipids in their structure and in their function in cells. [2]
  27. Summer 2022, AS Unit 1, Q2(b)(ii) (1 mark): State how the relative proportions of type A and B fatty acids in the diet can affect human health. [1]
  28. Summer 2022, AS Unit 1, Q5(b)(i) (2 marks): Complete Image 5.2 to show the digestion of lactose. [2]
  29. Summer 2022, AS Unit 1, Q5(b)(ii) (2 marks): State: I. the type of reaction; [1] II. the names of the products of digestion of lactose. [1]
  30. Summer 2022, AS Unit 1, Q5(c)(ii) (1 mark): Lactose is a reducing sugar. Explain why it is not possible to use Benedict’s reagent to monitor the progress of the digestion of lactose by lactase. [1]
  31. Summer 2022, AS Unit 1, Q6(a)(i) (1 mark): Name the highest level of protein structure shown by fibrinogen. [1]
  32. Summer 2022, AS Unit 1, Q6(b) (3 marks): Thrombin is an enzyme which is secreted into blood plasma when tissues are damaged. It catalyses the conversion of fibrinogen, in plasma, into the insoluble, fi
  33. Summer 2019, AS Unit 1, Q4(a) (1 mark): Define quaternary structure. [1]
  34. Summer 2019, AS Unit 1, Q4(e)(i) (1 mark): Draw a circle around the R-groups of these two amino acids. [1] The R-group of glutamic acid is polar whereas the R-group of valine is non-polar. This affects t
  35. Summer 2019, AS Unit 1, Q4(e)(ii) (3 marks): Valine interacts with phenylalanine and leucine in the beta-globin molecule. Phenylalanine and leucine both have non-polar R-groups. Explain how the properties
  36. Summer 2019, AS Unit 1, Q5(a)(i) (2 marks): Complete the diagram above to show how this molecule would be broken down into two monosaccharides. [2]
  37. Summer 2019, AS Unit 1, Q5(a)(ii) (1 mark): State the type of reaction that occurs when this molecule is broken down into two monosaccharides. [1]
  38. Summer 2019, AS Unit 1, Q5(a)(iii) (2 marks): Describe a biochemical test that could be used to determine the presence of a reducing sugar such as melibiose. [2]
  39. Summer 2019, AS Unit 1, Q6 (9 marks): The following extracts are adapted from articles published on the Internet. 6 Hidden ocean found on Saturn’s icy moon, Enceladus, could potentially support life
  40. Summer 2018, Unit 4, Q7(a)(ii) (1 mark): Bones are continually being remodelled for growth and repair, with calcium ions being both deposited and removed from the bone matrix. What is the name of the b
  41. Summer 2018, AS Unit 1, Q4(a)(i) (2 marks): Complete the diagram, to show the products formed when these amino acid molecules are joined by a condensation reaction. [2] H H CH3 O O H H N C C N C C H OH H
  42. Summer 2018, AS Unit 1, Q4(a)(ii) (1 mark): State the bond formed. [1]
  43. Summer 2018, AS Unit 1, Q4(b)(i) (1 mark): State the highest level of protein structure exhibited by the β-bungarotoxin. [1]
  44. Summer 2018, AS Unit 1, Q4(b)(ii) (2 marks): Name the structure labelled X and state how this structure is maintained. [2]
  45. Summer 2018, AS Unit 1, Q7 (9 marks): The diagram below shows the generalised structure of a seed. embryo plant cotyledon seed coat The cotyledon contains many organic molecules including starch and
  46. Summer 2017, Unit 4, Q7(b)(i) (3 marks): Label the diagram below to identify the regions of the antibody. [3] A B variable region C constant region D
  47. Summer 2017, Unit 4, Q7(b)(ii) (2 marks): Define the term antigen, and explain the meaning of an antigen-antibody complex. [2]
  48. Summer 2017, Unit 4, Q8(a)(i) (2 marks): Identify the main proteins found within each of the regions using ticks (√) to complete the following table. [2] Actin Myosin Troponin Tropomyosin A Band I Band
  49. Summer 2017, AS Unit 1, Q5(b)(iv) (2 marks): State how a diet high in animal products and cholesterol can lead to a person developing heart disease. [2]
  50. Summer 2017, AS Unit 1, Q6(a) (3 marks): Describe the role of magnesium, calcium, and phosphate ions in plant cells and tissues. [3] To investigate the uptake of mineral ions by plants, barley seedling
  51. Summer 2016, AS Unit 1, Q3(c) (4 marks): During the day the concentration of solutes in the pond water changes due to evaporation. However, the length of the spirogyra cells remain almost constant. Wha
  52. Summer 2016, AS Unit 1, Q4(a)(i) (2 marks): Complete the diagram to show the hydrolysis of sucrose including the products formed. [2] CH2OH CH2OH O O OH HO CH2OH HO O OH OH
  53. Summer 2016, AS Unit 1, Q4(a)(ii) (1 mark): State the name of the bond broken during the reaction. [1]
  54. Summer 2016, AS Unit 1, Q4(a)(iii) (1 mark): Explain why glucose and fructose are referred to as structural isomers. [1]

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