A student compares two amylase reactions. The same volume and concentration of amylase are used in each reaction.
Table
| Reaction | pH | Temperature / ∘C^{\circ}\mathrm{C}∘C | Initial starch concentration / % |
|---|---|---|---|
| P | 5 | 30 | 1 |
| Q | 7 | 30 | 2 |
Starch disappears sooner in P than in Q.
Which change would allow the effect of pH to be compared fairly?
Use 2%2\%2% starch in Q and increase its temperature to 40 ∘C40\,^{\circ}\mathrm{C}40∘C.
Use pH 5 in Q and keep its starch concentration at 2%2\%2%.
Use 1%1\%1% starch in Q and keep both temperatures at 30 ∘C30\,^{\circ}\mathrm{C}30∘C.
Use pH 7 in P and decrease its temperature to 20 ∘C20\,^{\circ}\mathrm{C}20∘C.
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.