Question 1

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

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, while anabolic pathways consume energy to build complex molecules.

Question 2

A bear eats a fish and then runs, as shown in the images. Which law of thermodynamics is illustrated by the conversion of chemical energy in food to kinetic energy and heat?

Accepted Answer

The first law of thermodynamics, because energy is transformed but not created or destroyed.

Question 3

In the process of gasoline combustion in a car engine, most of the chemical energy in gasoline is converted to which form of energy?

Accepted Answer

Thermal energy (heat) lost to the surroundings.

Question 4

Which of the following statements about Gibbs free energy ($$\Delta G) is $$correct?

Accepted Answer

$$\Delta G is $$negative for all spontaneous processes.

Question 5

Which of the following best explains why living organisms do not violate the second law of thermodynamics?

Accepted Answer

Organisms increase the entropy of their surroundings, so the total entropy of the universe increases.

Question 6

Which molecule has higher free energy: ATP or ADP? Why is this important for cellular work?

Accepted Answer

ATP has higher free energy, and its hydrolysis releases energy that can be used for cellular work.

Question 7

Which of the following is true about exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions release energy and have $$\Delta G \u003c 0.$$

Question 8

A chemical reaction has a large activation energy barrier. What role does an enzyme play in this reaction?

Accepted Answer

It lowers the activation energy, speeding up the reaction.

Question 9

Which of the following best describes the induced fit model of enzyme function?

Accepted Answer

The enzyme changes shape to fit the substrate more closely after binding.

Question 10

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 allosteric site on the first enzyme, inhibiting its activity.

Question 11

Which of the following is a correct statement about allosteric regulation of enzymes?

Accepted Answer

Allosteric activators stabilize the active form of the enzyme, increasing activity.

Question 12

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

Accepted Answer

It binds to a site other than the active site, changing the enzyme's shape and reducing activity.

Question 13

Which of the following is an example of energy coupling in cells?

Accepted Answer

The use of ATP hydrolysis to drive an endergonic reaction.

Question 14

Which of the following statements about cofactors is correct?

Accepted Answer

Cofactors can be inorganic ions or organic molecules that assist enzyme activity.

Question 15

A metabolic pathway consists of several steps, each catalyzed by a different enzyme. What would happen if the end product of the pathway accumulates?

Accepted Answer

The end product would inhibit the first enzyme, slowing or stopping the pathway (feedback inhibition).

Question 16

Which of the following best describes the difference between open and closed systems in thermodynamics?

Accepted Answer

Open systems can exchange both energy and matter with their surroundings, while closed systems cannot.

Question 17

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

Accepted Answer

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

Question 18

Which of the following is an example of cooperativity in enzyme regulation?

Accepted Answer

A substrate binding to one active site increases the activity at other active sites in a multi-subunit enzyme.

Question 19

Which of the following best describes the relationship between free energy, stability, and equilibrium in a chemical system?

Accepted Answer

As free energy decreases, the system becomes more stable and moves toward equilibrium.

Energy, Metabolism, and Enzyme Function in Cells

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