AS level Biology Paper 1

Which statements about the effect of all enzyme inhibitors are correct?

• 1, 2, and 3

• 1 and 2 only

• 1 and 3 only

• 3 only

The graphs show the rate of reaction of an enzyme-catalyzed reaction.

Which graph shows the effect of increasing the concentration of the substrate at two different concentrations of a competitive inhibitor?

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• 
• 
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Which statements are true about the optimum temperature of all enzymes?

• 1, 2 and 3

• 2 and 3 only

• 1 only

• 3 only

Some inhibitors of enzyme reactions bind to the enzyme-substrate complex.

Which statements about this type of inhibition are correct?

• 2, 3 and 4

• 1 and 2

• 1 and 3

• 2 and 3 only

The enzyme DNA polymerase is used in DNA replication. This enzyme was extracted from bacteria living in natural hot water springs where the water temperature is between 85 °C and 95 °C.

Which graph would represent the relationship between temperature and the rate of DNA replication when catalyzed by the enzyme from these bacteria?

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• 
• 
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Which row about competitive inhibitors of enzymes is correct?

• A

• B

• C

• D

In two investigations, the rate of an enzyme-catalysed reaction was measured in the presence of

either a competitive inhibitor or a non-competitive inhibitor.

What could be the effect of increasing the substrate concentration on each rate of reaction?

• A

• B

• C

• D

Two enzymes, X and Y, were used in an experiment. Enzyme X was from bacteria that live in rivers and lakes at temperatures from 5 °C to 20 °C. Enzyme Y was from bacteria that live in hot water springs at temperatures from 40 °C to 85 °C.

The experiment measured the concentration of product produced by each enzyme at temperatures between 0 °C and 100 °C after 5 minutes.

Which graph shows the results?

• 
• 
• 
• 

Which statement is only true for the induced fit theory of enzyme action?

• A few amino acids give the active site a specific shape.

• An enzyme has a substrate with a specific shape.

• The enzyme changes shape in the presence of the substrate.

• The substrate molecules are complementary to the active site.

The effect of substrate concentration on an enzyme-catalyzed reaction was measured in three different conditions:

● with no inhibitor

● with inhibitor X

● with inhibitor Y.

The graph shows the results.

Which statement is correct?

• X is a competitive inhibitor which binds away from the active site of the enzyme.

• X is a non-competitive inhibitor which has a similar shape to the substrate.

• Y is a competitive inhibitor which has a similar shape to the substrate.

• Y is a non-competitive inhibitor which binds away from the active site of the enzyme.