A student investigates the effect of pH on amylase activity at 35 ∘C35\,^{\circ}\mathrm{C}35∘C. The starch solution and amylase solution are initially at room temperature.
Which procedure gives the most valid comparison between pH values?
Mix both solutions at room temperature, warm them, then start timing at 35 ∘C35\,^{\circ}\mathrm{C}35∘C.
Warm both solutions separately to 35 ∘C35\,^{\circ}\mathrm{C}35∘C, mix them, then start timing immediately.
Warm only the starch solution to 35 ∘C35\,^{\circ}\mathrm{C}35∘C, mix them, then start timing after a minute.
Warm only the amylase solution to 35 ∘C35\,^{\circ}\mathrm{C}35∘C, mix them, then start timing after a minute.
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.