Question 1

Which of the following best describes the activation energy ($$E_a) of a $$reaction?

Accepted Answer

The difference in energy between the substrate and the transition state.

Question 2

Enzymes are able to lower the activation energy of a reaction primarily by:

Accepted Answer

Stabilizing the transition state.

Question 3

Which of the following statements is TRUE regarding the effect of enzymes on reaction equilibrium?

Accepted Answer

Enzymes do not affect the equilibrium constant ($$K_{eq}) $$for the reactions they catalyze.

Question 4

A mutation in an enzyme reduces its ability to stabilize the transition state. What is the most likely effect on the reaction?

Accepted Answer

The activation energy ($$E_a) $$will increase.

Question 5

Which of the following is NOT a way that enzymes lower activation energy?

Accepted Answer

Increasing entropy of the system.

Question 6

Which of the following statements about enzyme-substrate binding is correct?

Accepted Answer

Binding energy between an enzyme and a substrate contributes to catalysis by stabilizing the transition state.

Question 7

Enzymes are highly specific for their substrates. This specificity is primarily due to:

Accepted Answer

The precise arrangement of amino acids in the active site.

Question 8

Which of the following best explains why enzymes do not drive reactions to completion?

Accepted Answer

Enzymes only lower activation energy, not change equilibrium.

Question 9

Which of the following is a consequence of enzymes reducing entropy in the transition state?

Accepted Answer

It increases the likelihood of productive collisions between substrates.

Question 10

Which of the following statements about catalysis by proximity is correct?

Accepted Answer

Catalysis by proximity involves the enzyme orienting substrates to react more easily.

Question 11

A researcher observes that an enzyme increases the rate of a reaction but does not alter the final concentrations of reactants and products. This observation is best explained by which property of enzymes?

Accepted Answer

Enzymes lower the activation energy but do not affect equilibrium.

Question 12

Which of the following is a direct result of enzymes stabilizing the transition state?

Accepted Answer

The reaction rate increases.

Question 13

Which of the following is NOT a function of enzyme binding energy?

Accepted Answer

Increasing the entropy of the substrate.

Question 14

Which of the following statements about the transition state is correct?

Accepted Answer

The transition state has higher energy than both the substrate and the product.

Question 15

Which of the following best describes the role of entropy in enzyme catalysis?

Accepted Answer

Enzymes decrease entropy by orienting substrates for reaction.

Question 16

Which of the following is a unique property of enzymes compared to other catalysts?

Accepted Answer

Enzymes are highly specific for their substrates.

Question 17

Which of the following is a reason why enzymes increase reaction rates?

Accepted Answer

Enzymes stabilize the transition state.

Question 18

Which of the following statements about enzyme catalysis is FALSE?

Accepted Answer

Enzymes are consumed during the reaction.

Question 19

Which of the following is a direct effect of an enzyme binding its substrate in the correct orientation?

Accepted Answer

It increases the likelihood of a productive reaction.

Question 20

Which of the following best explains why enzymes are not consumed in the reactions they catalyze?

Accepted Answer

Enzymes are regenerated after each reaction cycle.

Activation Energy and Enzyme Catalysis: Mechanisms and Effects

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