Practise CAIE AS Biology 3.2 by interpreting how temperature, pH, enzyme and substrate concentrations, inhibitors and immobilisation affect enzyme activity.
A student investigated the hydrolysis of lipid in high-fat milk, using the enzyme lipase.
- of enzyme solution was added to 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.
1, 2 and 3
1 and 2 only
1 and 3 only
2 and 3 only
Which aspect of enzyme activity can be compared by the Michaelis-Menten constant?
activation energy of a reaction with or without an enzyme
affinity of different enzymes for their substrates
affinity of an enzyme at different substrate concentrations
maximum rate of reaction ( ) at different temperatures
The effect of substrate concentration on an enzyme-catalysed reaction was measured in three different conditions:
- without an inhibitor
- with a competitive inhibitor
- with a non-competitive inhibitor.
The graph shows the results.
Which row is correct?
without an inhibitor
with a competitive inhibitor
with a non-competitive inhibitor
1
2
3
1
3
2
3
1
2
3
2
1