Pyrophosphatase enzymes catalyse a hydrolysis reaction. C $$\(\xrightarrow{\text { key }}=\)$$ experiment 1

3.1.1 state that enzymes are globular proteins that catalyse reactions inside cells (intracellular enzymes) or are secreted to catalyse reactions outside cells (extracellular enzymes)

3.1.2 explain the mode of action of enzymes in terms of an active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis

3.1.3 investigate the progress of enzyme-catalysed reactions by measuring rates of formation of products using catalase and rates of disappearance of substrate using amylase

3.1.4 outline the use of a colorimeter for measuring the progress of enzyme-catalysed reactions that involve colour changes