Amylase in saliva starts to break down starch in the mouth. The pH in the mouth is about pH 7.
Food is then swallowed and enters the stomach. The pH in the stomach is about pH 2.
Explain why amylase stops breaking down starch when it enters the stomach.
A piece of bread begins to taste sweet if it is chewed for a long time.
Explain why.
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.