plumiHow enzymes work: Edexcel International A Level Biology questions
Edexcel International A Level Biology past-paper questions on 2.3.3 How enzymes work, 2019–2025, with mark schemes and examiner’s reports where available.
All papers
All years
Q7(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ7(b)(iii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ7(c)(i)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ7(c)(ii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ7(d)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ8(h)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ6(c)(i)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ6(c)(ii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(b)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ8(b)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ2(a)(i)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ2(a)(ii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ2(a)(iii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ5(c)(iii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ2(a)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ2(b)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ6(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ8(a)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ4(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ4(b)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFYour answer
All 34 questions on How enzymes work, as a list
- June 2025, AS Unit 1, Q7(a) (2 marks): The interaction between enzyme and substrate can be improved by changing the properties of the active site. Explain what determines the properties of an active
- June 2025, AS Unit 1, Q7(b)(iii) (2 marks): Suggest why changing the bonding could affect the binding of the plastics to the active site of the enzyme. (2)
- June 2025, AS Unit 1, Q7(c)(i) (2 marks): Suggest how a larger active site could increase the rate of breakdown of plastic. (2)
- June 2025, AS Unit 1, Q7(c)(ii) (1 mark): Suggest why an enzyme with a larger active site may be less active. (1)
- June 2025, AS Unit 1, Q7(d) (2 marks): One way of improving the activity of an enzyme is to link it to a different enzyme. The diagram shows two different enzymes linked together. enzyme 1 enzyme 2 E
- January 2025, Unit 5, Q8(h) (2 marks): Explain one reason why some people are not able to tolerate cow’s milk (paragraphs 30 and 31). (2)
- October 2024, AS Unit 1, Q6(c)(i) (2 marks): Explain why the scientists used digested soybeans to make the extract for this investigation. (2)
- October 2024, AS Unit 1, Q6(c)(ii) (1 mark): Suggest why the soybean flour was incubated with different enzymes in steps 2 and 3. (1)
- June 2024, AS Unit 1, Q6(b)(ii) (2 marks): Explain why this amylase is able to break only 1–4 glycosidic bonds. (2)
- June 2024, AS Unit 2, Q8(b)(ii) (1 mark): Suggest one reason for the difference in breakdown of the wood by species A and species B. (1)
- October 2023, AS Unit 1, Q2(a)(i) (1 mark): Which arrow shows the activation energy for this reaction? (1) A P B Q C R D S
- October 2023, AS Unit 1, Q2(a)(ii) (1 mark): Which row of the table shows the molecule present at time Y and time Z on this graph? (1) Time Y Time Z A product monophenol reactant o‑diphenol B product o‑dip
- October 2023, AS Unit 1, Q2(a)(iii) (1 mark): Which row of the table shows how the length of the arrows P and Q on this graph would change when polyphenol oxidase is present? (1) Change in length of arrow P
- June 2023, AS Unit 1, Q5(c)(iii) (2 marks): Thrombin slowly splits variegin into two molecules. Explain how thrombin splits variegin. (2)
- June 2023, Unit 5, Q2(a)(ii) (1 mark): Enzymes are involved in the production of ATP by the electron transport chain. Which type of molecule is an enzyme? (1) A carbohydrate B lipid C phospholipid D
- January 2023, AS Unit 1, Q2(b)(ii) (3 marks): Explain how a protease breaks down elastin. (3)
- January 2023, Unit 4, Q6(a) (1 mark): Which describes an enzyme in a living organism? (1) A inorganic substance that decreases activation energy B inorganic substance that increases activation energ
- January 2023, Unit 4, Q8(a)(ii) (3 marks): The diagram shows this polyprotein and the function of some of the individual proteins it contains. The arrows indicate where the individual proteins need to be
- October 2022, AS Unit 1, Q4(a) (2 marks): State the meaning of the term biological catalyst. (2)
- October 2022, AS Unit 1, Q4(b) (1 mark): The graph shows the energy changes during an enzyme catalysed reaction. Energy Q R S P Time Which arrow shows the energy required to start the reaction? (1) A P
- October 2022, AS Unit 1, Q4(c) (3 marks): The diagram shows a series of chemical reactions. E1 E2 E3 A + B AB AC D Three different enzymes, E1, E2 and E3, are involved in these reactions. Explain why E1
- June 2022, AS Unit 1, Q3(a) (1 mark): What type of molecule is pectinase? (1) A disaccharide B polysaccharide C protein D triglyceride
- June 2022, AS Unit 1, Q3(b) (2 marks): Explain why enzymes are described as biological catalysts. (2)
- October 2021, Unit 5, Q8(e) (3 marks): Suggest how gingipains may have a degrading effect on the memory of a person suffering from Alzheimer’s disease (paragraph 12). (3)
- June 2021, Unit 6, Q1(c) (3 marks): Calcium ions can bind to some enzymes. Explain how the presence of calcium ions can affect the time taken for brine shrimp eggs to hatch. (3)
- January 2021, AS Unit 1, Q8(a)(ii) (3 marks): Explain how the three-dimensional structure of lactase affects the mechanism of action of this enzyme. (3)
- January 2021, AS Unit 1, Q8(b)(i) (1 mark): Suggest one advantage of using immobilised lactase. (1)
- October 2020, AS Unit 1, Q7(c)(i) (2 marks): The diagrams show the structures of warfarin and vitamin K. O OH O O Warfarin O O Vitamin K Using the information in the diagrams, suggest why warfarin inhibits
- October 2020, AS Unit 1, Q7(c)(ii) (2 marks): Suggest why people taking warfarin have to avoid eating foods that contain a high concentration of vitamin K. (2)
- October 2020, Unit 5, Q8(e) (4 marks): Explain how ‘a gene variant that produces a defective form of an enzyme’ reduces the effectiveness of clopidogrel (paragraph 16). (4)
- January 2020, AS Unit 1, Q3(a)(i) (1 mark): The diagrams show symbols for lactase, lactose and the monosaccharides of lactose. lactase lactose monosaccharides Which diagram shows the sequence of events fo
- January 2020, AS Unit 1, Q3(b) (1 mark): The graph shows the energy changes for the hydrolysis of lactose, with and without lactase. line P Q R Energy Course of reaction Which row in the table describe
- January 2019, AS Unit 1, Q6(b) (4 marks): Thrombin inhibitors are drugs that have an effect on the time taken for blood to clot. Explain why thrombin inhibitors affect the time taken for blood to clot.
- January 2019, AS Unit 1, Q7(c) (6 marks): The gall-forming insects secrete saliva into the plant tissues. The saliva contains enzymes that change the nutrients in the leaf and cause the galls to form. T
Questions, mark schemes and examiner’s reports are © Pearson Edexcel, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Edexcel International A Level Biology past papers.
The Plumi iPad app also offers exam-style questions with AI feedback on your handwritten working.