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 7 of 7 written questions. Open one to see it on the real paper.
- 0973/41 · 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 → - 0973/31 · May/June 2024 · Q10b[1]
State one factor, other than temperature, that affects enzyme activity.
See it on the paper → - 0973/32 · May/June 2022 · Q4a[3]
Different digestive enzymes work best at different pH values. The best pH for enzyme activity is called its optimum pH. Fig. 4.1 shows the optimum pH of five different digestive enzymes. 9 8 7 6 5 optimum pH 4 3 2 1 0 A B C enzyme D E Fig. 4.1 Use Fig. 4.1 to complete these sentences. The enzyme with the lowest optimum...
See it on the paper → - 0973/32 · May/June 2022 · Q4b[1]
Name one factor, other than pH, that affects enzyme activity.
See it on the paper → - 0973/41 · May/June 2020 · Q1b[3]
Photosynthesis is an enzyme-controlled reaction. Explain the results between 55–65 °C.
See it on the paper → - 0973/41 · October/November 2019 · Q7a(iii)[3]
The investigation is repeated at a temperature of 80 °C. Explain the effect this would have on the result.
See it on the paper → - 0973/42 · May/June 2019 · Q1b[3]
Enzyme activity is also affected by pH. Complete the graph in Fig. 1.2 to show how the activity of a protease enzyme in the stomach is affected by pH. Include on your graph: • • labels for both axes a sketch of a suitable curve. 1 2 3 4 5 6 7 8 9 10 11 12 Fig. 1.2
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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, 0973/41 Q1(c) (Cambridge)
The most common error that prevented candidates from achieving full credit was to draw the peak of the graph at neutral rather than in the acidic region. Most candidates labelled the axes correctly.
— Examiner report, May/June 2019, 0973/42 Q1(b) (Cambridge)
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