An enzyme-controlled reaction is slow at 5 ∘C5\,^{\circ}\mathrm{C}5∘C. The mixture is warmed to 25 ∘C25\,^{\circ}\mathrm{C}25∘C, below the optimum temperature, and the reaction becomes faster.
Which statement explains the increase in rate?
The particles move slower, so successful collisions occur more frequently.
The particles move faster, so successful collisions occur more frequently.
The active sites become larger, so different substrates can fit inside.
The active sites become smaller, so different substrates can fit inside.
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.