Lipase is added to a lipid suspension. Fatty acids are produced, and the pH falls below the optimum pH of the lipase.
Lipid is still present, but the reaction becomes slower.
Which statement best explains this decrease in rate?
The pH change affects active-site shape, so fewer substrate molecules bind.
The lipid changes into lipase, so fewer substrate molecules can be broken down.
The fatty acids become active sites, so fewer enzyme molecules are available.
The pH change lowers temperature, so fewer substrate molecules can move.
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.