Enzyme Activity and Inhibition Quiz

An enzyme is completely denatured at 50°C. A fixed concentration of this enzyme is added to a fixed concentration of its substrate. The time taken for completion of the reaction is measured at different temperatures. Which graph shows the results?

• Graph A

• Graph B

• Graph C

• Graph D

Which properties are characteristic of a non-competitive inhibitor of an enzyme?

• Binding at active site, reduces inhibition

• Binding at active site, does not reduce inhibition

• Binding not at active site, reduces inhibition

• Binding not at active site, does not reduce inhibition

A piece of mammalian tissue was homogenised and subjected to differential centrifugation to yield four subcellular fractions. The activity within each fraction, of four different types of enzyme A, B, C and D, was investigated. Which bar chart shows the results of investigating hydrolytic enzyme activity?

• Chart A

• Chart B

• Chart C

• Chart D

A metabolic pathway is shown as: enzyme 1 converts reactant to substance X, enzyme 2 converts substance X to substance Y, and enzyme 3 converts substance Y to end product. What would be the effect of adding a small amount of a non-competitive inhibitor of enzyme 2?

• Enzyme 2 would be partially denatured.

• Substance X would increase in concentration.

• Substance Y would no longer be formed.

• The initial reactant would no longer be metabolised.

Which graph shows the effect of a low concentration of non-competitive inhibitor on the reaction?

• Graph A: A graph with a plateau indicating inhibited reaction at high substrate concentration.

• Graph B: A linear graph showing no inhibition.

• Graph C: A graph with a steep curve indicating strong inhibition.

• Graph D: A graph with a slight curve indicating moderate inhibition.

Which statement explains the enzyme activity at the point shown?

• At P, hydrogen bonds are formed between enzyme and substrate.

• At Q, the kinetic energy of enzyme and substrate is highest.

• At R, peptide bonds in the enzyme begin to break.

• At S, the substrate is completely denatured.

Which graph shows the results of experiment X, carried out at a constant temperature of 37°C?

• A

• B

• C

• D

Which properties are characteristic of a non-competitive inhibitor of an enzyme?

• A) Binding at active site, reduces inhibition

• B) Binding at active site, does not reduce inhibition

• C) Binding not at active site, reduces inhibition

• D) Binding not at active site, does not reduce inhibition

The rate of enzyme catalysed reactions in human cells is regulated. Which of the following may be involved in such regulation?

• 1 only

• 3 only

• 1 and 2 only

• 1, 2 and 3

A piece of mammalian tissue was homogenised and subjected to differential centrifugation to yield four subcellular fractions. The activity of four different types of enzyme, A, B, C and D, was investigated within each fraction. Which bar chart shows the results of investigating hydrolytic enzyme activity?

• Chart A

• Chart B

• Chart C

• Chart D