CAIE A-Level Biology AS 3 Enzymes Topic Practice

The diagram shows a simple metabolic pathway.

The letters W, X, Y and Z represent four different substances. At each step in the diagram the substrate undergoes a chemical reaction catalysed by an enzyme. The reaction produces the next substance in the pathway.

Which statements correctly describe the enzymes taking part in this metabolic pathway?
1 They are all globular proteins.
2 They all have the same tertiary structure.
3 They all contain hydrogen atoms in their structure.

A student investigated the hydrolysis of lipid in high-fat milk, using the enzyme lipase.
- $1 \mathrm{~cm}^{3}$ of enzyme solution was added to $10 \mathrm{~cm}^{3}$ of high-fat milk.
- The temperature was kept constant.
- The pH of the reaction mixture was recorded at time 0 minutes and every minute for 20 minutes.

Which statements correctly describe the expected results of this investigation?

1 The product forms more slowly as time proceeds because the concentration of the substrate is decreasing.

2 The pH of the reaction mixture increases rapidly in the first few minutes and then increases less rapidly.

3 The increase in the concentration of product eventually causes the lipase molecules to denature.

The diagram shows different molecules in a solution.

Which statement could explain what happens when some of the molecules are mixed together?

Which aspect of enzyme activity can be compared by the Michaelis-Menten constant?