Lipase is an enzyme that catalyses the hydrolysis of lipids. An experiment was carried out to investigate changes in pH when lipase is added to a food sample containing a high proportion of lipids. The results are shown in the graph. [Figure 13.1] Which statements are possible explanations of the results of the experiment between 50 minutes and 60 minutes? 1 Enzyme concentration becomes the limiting factor. 2 Substrate concentration becomes the limiting factor. 3 All the enzyme active sites are occupied. 4 Denaturation of the enzyme by the products takes place. 5 Products are acting as competitive inhibitors.

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.