0653.B5.1.04 — Explain the effect of changes in pH on enzyme activity in terms of shape and fit and denaturation: past paper questions
Real questions on 0653.b5.1.04 — explain the effect of changes in ph on enzyme activity in terms of shape and fit and denaturation
The newest 12 of 12 written questions. Open one to see it on the real paper.
- 0653/43 · October/November 2025 · Q1b(ii)[3]
Explain the effect of pH 7 on the activity of enzyme S.
See it on the paper → - 0653/32 · May/June 2025 · Q3c(i)[2]
Fig. 3.1 is a graph that shows the effect of pH on the enzyme activity of one enzyme. enzyme activity 0 2 4 6 pH 8 10 12 Fig. 3.1 Describe the effect of pH on enzyme activity shown in Fig. 3.1. Include data in your answer.
See it on the paper → - 0653/32 · May/June 2025 · Q3c(ii)[1]
State one factor that affects enzyme activity, other than pH.
See it on the paper → - 0653/41 · May/June 2025 · Q2b[3]
Flowers produce seeds. Germination of seeds uses enzymes. The graph in Fig. 2.2 shows the effect of pH on an enzyme. enzyme activity 2 3 4 5 6 7 8 9 10 pH Fig. 2.2 Explain the effect of pH 10 on the enzyme in Fig. 2.2.
See it on the paper → - 0653/43 · May/June 2025 · Q2c(ii)[3]
Enzymes are involved in photosynthesis. Explain the result at 40 °C shown in Fig. 2.2.
See it on the paper → - 0653/42 · May/June 2024 · Q1c[3]
A lipase enzyme is found in the alimentary canal. Fig. 1.2 shows the activity of this lipase enzyme at different pH values. activity of lipase 3 4 5 6 7 pH 8 9 10 11 12 Fig. 1.2 Explain why this lipase enzyme is not active in the stomach. Use data from Fig. 1.2 in your answer. ,
See it on the paper → - 0653/42 · February/March 2024 · Q1d[2]
Fig. 1.2 is a graph showing the effect of pH on enzyme A and enzyme B. enzyme B enzyme A enzyme activity 0 2 4 6 pH 8 10 12 Fig. 1.2 State which of the enzymes in Fig. 1.2 is found in gastric juice. Explain your answer using evidence from Fig. 1.2. enzyme explanation
See it on the paper → - 0653/33 · October/November 2023 · Q7a(i)[2]
Describe the effect of pH on the enzyme activity. Include data from Fig. 7.1 in your answer.
See it on the paper → - 0653/22 · May/June 2023 · Q3[1]
What occurs when the temperature rises above the temperature at which the enzyme works best?
See it on the paper → - 0653/42 · February/March 2023 · Q4b(ii)[3]
Explain the effect of a temperature of 80 °C on the activity of enzyme C as in Fig. 4.1.
See it on the paper → - 0653/11 · May/June 2020 · Q5[1]
An enzyme can stop working at certain temperatures. Which enzyme stops working when the temperature reaches 50 °C?
See it on the paper → - 0653/11 · May/June 2020 · Q8[1]
A student investigated the effect of pH on the rate of reaction of an enzyme. The student used buffer solutions of different pH values. What is the optimum pH for this enzyme?
See it on the paper →
What examiners said
The relationship between pH and enzyme activity was described correctly by most candidates. The highest activity, at pH6.8, was also identified successfully. Some candidates stated that after the peak the enzyme denatured without stating how this affects the activity. Candidates should take special care to read the question and respond accordingly.
— Examiner report, May/June 2025, 0653/32 Q3(c)(i) (Cambridge)
The details of the denaturing of enzymes, loss of the shape of the active site and consequent inability to bind with the substrate had been learned very well by many candidates. All of these ideas were required for full credit. Common reasons for credit being missed included omitting to use the term active site, omitting to state that the shape of the active site changes or suggesting that the act...
— Examiner report, May/June 2025, 0653/41 Q2(b) (Cambridge)
Most candidates correctly used the term denaturing. A common error was the term ‘denaturalising’. Candidates who understood that the shape of the active site is no longer complementary to the substrate generally gained full credit.
— Examiner report, May/June 2025, 0653/43 Q2(c)(ii) (Cambridge)
Past papers, syllabus and examiner reports © UCLES (Cambridge University Press & Assessment). Questions are matched to topics from the official syllabus. AssessPro is independent and not endorsed by Cambridge.