A student measures the initial rate of an enzyme-controlled reaction at four temperatures. All other conditions are kept the same.
Table
| Temperature / ∘C^{\circ}\mathrm{C}∘C | Initial rate / arbitrary units |
|---|---|
| 15 | 4 |
| 25 | 9 |
| 35 | 16 |
| 55 | 2 |
Which statement best explains the results at 35 ∘C35\,^{\circ}\mathrm{C}35∘C and 55 ∘C55\,^{\circ}\mathrm{C}55∘C?
At 55 ∘C55\,^{\circ}\mathrm{C}55∘C particles move slower, but more active sites retain their shape.
At 55 ∘C55\,^{\circ}\mathrm{C}55∘C particles move faster, so fewer enzyme–substrate collisions occur.
At 55 ∘C55\,^{\circ}\mathrm{C}55∘C particles move slower, so more enzyme–substrate collisions occur.
At 55 ∘C55\,^{\circ}\mathrm{C}55∘C particles move faster, but fewer active sites retain their shape.
44 exam-style questions on Edexcel GCSE Biology 1.3 Enzymes, covering 1.3.1 Mechanism of enzyme action, 1.3.2 Denaturation of enzymes, 1.3.3 Factors affecting enzyme activity, and 1.3.4 Measuring energy in food by calorimetry. Each one has a worked solution and a mark scheme showing where the marks go.