Question 1

Which of the following best describes the relationship between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, and this energy is used to drive anabolic pathways that build complex molecules.

Question 2

According to the first law of thermodynamics, which of the following statements is correct?

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 3

A bear catches a fish and metabolizes it for energy. According to the second law of thermodynamics, what happens to the energy from the fish?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the universe.

Question 4

Which equation correctly represents the change in free energy for a chemical reaction?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 5

A reaction has $$\Delta G = -7.3$$ kcal/mol. Which of the following is true about this reaction?

Accepted Answer

The reaction is spontaneous and can perform work.

Question 6

Which of the following best explains why living cells never reach metabolic equilibrium?

Accepted Answer

Cells constantly allow materials to flow in and out, preventing equilibrium and allowing continuous work.

Question 7

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when the terminal phosphate bond is broken by hydrolysis.

Question 8

How do enzymes speed up chemical reactions?

Accepted Answer

By lowering the activation energy ($$E_A) $$required for the reaction.

Question 9

Which of the following is an example of feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway, inhibiting its activity.

Question 10

Which of the following best describes the effect of a competitive inhibitor on an enzyme?

Accepted Answer

It binds to the active site, blocking the substrate from binding.

Question 11

A scientist mutates an enzyme so that its active site no longer binds its substrate. What is the most likely result?

Accepted Answer

The enzyme will no longer catalyze the reaction.

Question 12

Which of the following is true about the optimal temperature and pH for enzyme activity?

Accepted Answer

Enzymes have different optimal temperatures and pH values depending on their environment.

Question 13

Which of the following statements about energy coupling in cells is correct?

Accepted Answer

Energy coupling uses an exergonic process, such as ATP hydrolysis, to drive an endergonic process.

Question 14

Which of the following is a correct statement about the flow of energy and matter in living systems?

Accepted Answer

Matter is recycled, but some energy is always lost as heat.

Question 15

Which of the following best explains why the hydrolysis of ATP is used to drive endergonic reactions in cells?

Accepted Answer

ATP hydrolysis is highly exergonic, providing energy to make endergonic reactions overall exergonic.

Question 16

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

Accepted Answer

Changing the $$\Delta G of $$the reaction.

Question 17

Which of the following is true about allosteric regulation of enzymes?

Accepted Answer

Allosteric regulation can either inhibit or activate enzyme activity by binding to a site other than the active site.

Question 18

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein helpers that are required for some enzymes to function.

Question 19

A metabolic pathway consists of several steps, each catalyzed by a specific enzyme. What would happen if the enzyme for the second step is nonfunctional?

Accepted Answer

The pathway would stop at the intermediate before the nonfunctional enzyme.

Question 20

Which of the following forms of energy is least useful to living organisms?

Accepted Answer

Energy in the form of heat.

Metabolism, Thermodynamics, and Enzyme Function in Biological Systems

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