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 chemical reaction has a $$\Delta G = -5.0$$ kcal/mol. Which statement is true about this reaction?

Accepted Answer

The reaction is spontaneous and releases free energy.

Question 3

Which of the following is an example of potential energy in a biological system?

Accepted Answer

A glucose molecule before it is broken down in cellular respiration.

Question 4

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

Accepted Answer

Every energy transfer increases the disorder (entropy) of the universe.

Question 5

Refer to the hydroelectric dam diagrams. Why does the isolated hydroelectric system eventually stop producing energy?

Accepted Answer

Because the system reaches equilibrium and $$\Delta G = 0.$$

Question 6

Which of the following best explains why cells must remain in an open system?

Accepted Answer

To continuously exchange energy and matter, preventing equilibrium and allowing metabolism to proceed.

Question 7

ATP hydrolysis releases energy because:

Accepted Answer

The bonds between phosphate groups in ATP are unstable and their hydrolysis is highly exergonic ($$\Delta G = -7.3$$ kcal/mol).

Question 8

Which of the following is NOT a way that enzymes lower the activation energy ($$E_A) of a $$reaction?

Accepted Answer

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

Question 9

A reaction has $$\Delta H = -10$$ kcal/mol, $$T = 300 K$$, and $$\Delta S = +0.02$$ kcal/(mol·K). What is $$\Delta G$$ for this reaction?

Accepted Answer

$$\Delta G = -10.6$$ kcal/mol

Question 10

Which of the following scenarios best illustrates energy coupling in cells?

Accepted Answer

ATP hydrolysis is used to drive the synthesis of glutamine from glutamic acid and ammonia, where the overall $$\Delta G is $$negative.

Question 11

Which of the following would most likely happen to an intestinal enzyme if it is placed in the stomach (pH 2)?

Accepted Answer

It would unfold and lose its three-dimensional structure.

Question 12

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

Accepted Answer

Enzymes lower the activation energy ($$E_A) $$but do not change the $$\Delta G of $$the reaction.

Question 13

Which of the following best describes the role of ATP in muscle contraction?

Accepted Answer

ATP provides the energy for myosin motors to move along actin filaments, causing contraction.

Question 14

Which of the following statements about metabolic pathways is correct?

Accepted Answer

Each step in a metabolic pathway is catalyzed by a specific enzyme.

Question 15

Which of the following is an example of an anabolic reaction?

Accepted Answer

The synthesis of a peptide bond between two amino acids.

Question 16

Which of the following best explains why high fevers can be lethal?

Accepted Answer

High temperatures cause enzymes to unfold, losing their function.

Question 17

Which of the following is a correct statement about cofactors?

Accepted Answer

Cofactors are non-protein helpers required for some enzymes to function.

Question 18

A reaction has $$\Delta H = +8$$ kcal/mol, $$T = 298 K$$, and $$\Delta S = +0.03$$ kcal/(mol·K). Is this reaction spontaneous?

Accepted Answer

No, because $$\Delta G is $$positive.

Question 19

Which of the following best describes the relationship between exergonic and endergonic reactions in cells?

Accepted Answer

Exergonic reactions can provide the energy required to drive endergonic reactions through energy coupling.

BIO 121 Chapter 8: Metabolism – Energy, Enzymes, and Cellular Work

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