0654.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 0654.b5.1.04 — explain the effect of changes in ph on enzyme activity in terms of shape and fit and denaturation
The newest 5 of 5 written questions. Open one to see it on the real paper.
- 0654/42 · October/November 2025 · Q3b(ii)[2]
The student finds that the amylase does not break down any of the starch at 55 °C. Explain why.
See it on the paper → - 0654/41 · May/June 2025 · Q1c[3]
The uptake and release of carbon dioxide by the same plant is measured on a different day. On this day, the temperature is lower than the previous day. This time, the net volume of carbon dioxide uptake levels out at –40 arbitrary units. Enzymes are required for photosynthesis. Explain this difference in net volume of...
See it on the paper → - 0654/22 · May/June 2022 · Q4[1]
Which effect will temperature change have on enzyme activity?
See it on the paper → - 0654/22 · October/November 2019 · Q4[1]
graph shows what happens if a similar starch-amylase mixture is incubated at 100 °C?
See it on the paper → - 0654/11 · May/June 2019 · Q4[1]
What is the optimum temperature for this enzyme?
See it on the paper →
What examiners said
Most candidates linked the reduction in carbon dioxide uptake to a reduction in the rate of photosynthesis. Only the strongest candidates were able to explain this reduction in terms of lower kinetic energy and lower frequency of successful collisions between enzymes and substrate.
— Examiner report, May/June 2025, 0654/41 Q1(c) (Cambridge)
In this question candidates had to choose which graph illustrated the amount of starch remaining in a starch amylase mixture incubated to 100 °C. Equal numbers chose the correct answer, and an answer that would have been correct for a mixture incubated at slightly more than body temperature, suggesting that they had not realised that such a high temperature would completely denature the enzyme.
— Examiner report, October/November 2019, 0654/22 Q4 (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.