AS level Biology Paper 2

The diagram shows an enzyme, its substrate and an enzyme/substrate complex. Name and describe the theory which explains how the substrate is able to enter the active site of the enzyme.

[3 marks]

The table contains results recorded by a student from an investigation into the effect of temperature on an enzyme-catalyzed reaction.

All other variables were kept constant.

Estimate the optimum temperature of the enzyme. Explain your answer with reference to the data.

[3 marks]

The graph shows the effect of substrate concentration on the rate of an enzyme-catalyzed reaction.

The purple line represents the enzyme without the inhibitor.

The green and blue lines represent the same enzyme with two different types of inhibitor.

Identify which line represents the enzyme with the non-competitive inhibitor. Give two reasons for your answer.

[3 marks]

Two inhibitors of the same enzyme were investigated to discover if they were competitive or non-competitive.

In order to do this, the rate of reaction of the enzyme was measured at different concentrations of substrate without inhibitor, with competitive inhibitor, and with non-competitive inhibitor.

Double-reciprocal plots of the data obtained produced the graphs shown.

State and explain the practical purpose of a double reciprocal graph used this way.

[3 marks]

Two inhibitors of the same enzyme were investigated to discover if they were competitive or non-competitive.

In order to do this, the rate of reaction of the enzyme was measured at different concentrations of substrate without inhibitor, with competitive inhibitor, and with non-competitive inhibitor.

Double-reciprocal plots of the data obtained produced the graphs shown. Z represents the enzyme without the inhibitor.

Complete this sentence: Graph ____ is with competitive inhibitor while graph ____ is with non-competitive inhibitor.

Explain your answer with reference to the graph.

[6 marks]

Give two advantages specific to immobilizing the enzyme lactase.

[2 marks]