Question 1

Which statement is true of a competitive enzyme inhibitor?

  A  

binds to a site other than the active site

  B  

can bind irreversibly to the active site

  C  

changes the shape of the active site

  D  

effects can be overcome by adding more substrate


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Question 2

Which statements about enzyme inhibitors are correct?

1 - competitive inhibitors may be similar shapes to the substrate

2 - competitive inhibitors bind to the active site

3 - non-competitive inhibitors alter the shape of the enzyme

4 - non-competitive inhibitors bind to the substrate

  A  

1 and 2

  B  

2 and 3

  C  

2, 3, and 4

  D  

1, 2, and 3

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Question 3

Why do large increases in the temperature or pH alter enzyme activity?

1 - they change the three-dimensional shape of the enzyme

2 - they disrupt hydrogen and ionic bonds in the enzyme

3 - they increase hydrophobic interactions in the enzyme

  A  

1 and 2

  B  

1 and 3

  C  

2 and 3

  D  

1 only

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Question 4

What is the effect of an enzyme in an enzyme-catalysed reaction?

  A  

decreases both the activation energy and the energy yield

  B  

decreases the activation energy and has no effect on the energy yield

  C  

increases both the activation energy and the energy yield

  D  

increases the energy yield and decreases the activation energy


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Question 5

Which of the bonds will be last to break as the temperature of an enzyme is increased?

  A  

covalent

  B  

hydrogen

  C  

hydrophobic interactions

  D  

ionic

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Question 6

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

1 - with no inhibitor

2 - with a competitive inhibitor

3 - with a non-competitive inhibitor

The graph shows the results.

Which statement is correct?

  A  

X is a competitive inhibitor which binds to a site other than the active site of the enzyme

  B  

X is a non-competitive inhibitor which has a similar shape to the active site of the enzyme

  C  

Y is a competitive inhibitor which has a similar shape to the active site of the enzyme

  D  

Y is a non-competitive inhibitor which binds to a site other than the active site of the enzyme

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Question 7

The graph shows the effect of temperature on the rate at which the enzyme in a biological washing powder digests and removes fruit juice stains.

Which statements explain the shape of the graph at temperatures higher than T?

1 - bonds are broken between the R groups of the amino acids in the polypeptide chains of the enzyme

2 - there are more collisions between the enzyme and its substrate

3 - the tertiary structure of the enzyme is altered

4 - the shapes of the active site and the substrate are no longer complementary

  A  

1, 2, and 3

  B  

1, 2, and 4

  C  

1, 3, and 4

  D  

2, 3, and 4

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Question 8

What determines the specificity of an enzyme?

  A  

the covalent and other bonding between R groups of the polypeptide


  B  

the optimum pH of the enzyme

  C  

the covalent peptide bonds between amino acids of the polypeptide

  D  

the shape of the substrate molecule

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Question 9

What determines the specificity of an enzyme?

  A  

the bonding between R groups of the polypeptide

  B  

the optimum pH of the enzyme

  C  

the peptide bonds between amino acids of the polypeptide

  D  

the shape of the substrate molecule

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Question 10

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

1 - change the shape of the active site

2 - denature the enzyme

3 - reduce the rate of the enzyme-catalysed reaction

  A  

1, 2, and 3

  B  

1 and 2 only

  C  

1 and 3 only

  D  

3 only

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Question 11

What is the correct definition of the term coenzyme?

  A  

an inorganic ion that forms the centre of a globular protein

  B  

a molecule that binds to the enzyme, changing the shape of the active site, preventing an enzyme substrate complex from forming

  C  

a non-protein organic molecule, not permanently attached to an enzyme, but needed to allow the enzyme to function

  D  

a metal ion that attaches to the enzyme, changing the shape of the active site, increasing the likelihood of a reaction

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