Question 1

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes lower the activation energy ($$E_a) $$required for a reaction to proceed.

Question 2

Hexokinase catalyzes the conversion of glucose to glucose-6-phosphate in glycolysis. Which of the following is TRUE about hexokinase?

Accepted Answer

Hexokinase is a molecular catalyst.

Question 3

Which of the following best describes how enzymes catalyze reactions?

Accepted Answer

They stabilize the transition state, lowering the activation energy.

Question 4

A mutation in an enzyme's active site prevents substrate binding. What is the most likely effect on the reaction it catalyzes?

Accepted Answer

The reaction will proceed at a much slower rate.

Question 5

Which of the following is NOT a property of enzymes?

Accepted Answer

They are consumed during the reaction.

Question 6

Which of the following statements about the effect of enzymes on chemical reactions is CORRECT?

Accepted Answer

Enzymes increase the rate at which a chemical reaction reaches equilibrium.

Question 7

Which of the following best explains why enzymes do NOT affect the thermodynamic favorability of a reaction?

Accepted Answer

Enzymes do not change the free energy difference ($$\Delta G) $$between reactants and products.

Question 8

Which of the following is a direct result of enzyme catalysis?

Accepted Answer

The reaction proceeds with a lower activation energy ($$E_a).$$

Question 9

A scientist observes that a reaction proceeds much faster in the presence of an enzyme, but the final ratio of products to reactants is unchanged. What does this observation suggest?

Accepted Answer

The enzyme decreased the activation energy ($$E_a).$$

Question 10

Which of the following is TRUE regarding the specificity of enzymes?

Accepted Answer

Enzymes bind specifically to their substrates due to the shape and chemical properties of their active sites.

Question 11

Which of the following best describes the role of ATP in enzyme-catalyzed reactions such as those involving hexokinase?

Accepted Answer

ATP acts as a substrate that donates a phosphate group.

Question 12

Which of the following is a common misconception about enzyme function?

Accepted Answer

Enzymes change the equilibrium constant ($$K_{eq}) of a $$reaction.

Question 13

Which of the following is the best explanation for why enzymes do not make nonspontaneous reactions spontaneous?

Accepted Answer

Enzymes only affect the activation energy, not the overall free energy change ($$\Delta G).$$

Question 14

Which of the following is TRUE about the effect of enzymes on the rate of chemical reactions?

Accepted Answer

Enzymes increase the rate by stabilizing the transition state.

Question 15

Which of the following statements about the equilibrium of enzyme-catalyzed reactions is CORRECT?

Accepted Answer

Enzymes increase the rate at which equilibrium is reached.

Enzymes: Biological Catalysts – Structure, Function, and Mechanism

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