Question 1

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

Accepted Answer

Catabolic pathways break down complex molecules to release energy, while anabolic pathways build complex molecules from simpler ones, requiring energy input.

Question 2

A chemical reaction has a change in free energy ($$\Delta G) of$$ $$-5$$ kcal/mol. Which of the following statements is true about this reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 3

Which equation correctly represents the relationship between free energy, enthalpy, entropy, and temperature?

Accepted Answer

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

Question 4

Why do C–H bonds have higher potential energy than O–H bonds?

Accepted Answer

C–H bonds are nonpolar, with electrons shared equally, resulting in longer, weaker bonds and higher potential energy.

Question 5

Which of the following is an example of the first law of thermodynamics in a biological system?

Accepted Answer

A bear running and releasing heat after eating fish, converting chemical energy to kinetic and thermal energy.

Question 6

Which process increases the entropy ($$S) of $$the universe according to the second law of thermodynamics?

Accepted Answer

Cellular respiration in animals.

Question 7

ATP hydrolysis is used to drive endergonic reactions in cells. Which statement best explains how this occurs?

Accepted Answer

ATP hydrolysis releases energy, which is coupled to endergonic reactions, making the overall process exergonic.

Question 8

Which of the following best describes the role of enzymes in metabolic reactions?

Accepted Answer

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

Question 9

A metabolic pathway consists of several enzyme-catalyzed steps. If the final product of the pathway inhibits the first enzyme by binding to a site other than the active site, this is an example of:

Accepted Answer

Feedback inhibition via allosteric regulation

Question 10

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Each enzyme recognizes a unique substrate due to the shape and chemical properties of its active site.

Question 11

A patient is given a drug that acts as a noncompetitive inhibitor of an essential metabolic enzyme. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor will bind to a different site, changing the enzyme's shape and reducing its activity.

Question 12

Which of the following best explains why enzymes have an optimal temperature and pH?

Accepted Answer

Enzyme structure and function depend on specific temperature and pH conditions; deviations can denature the enzyme and reduce activity.

Question 13

Which of the following is a correct example of energy coupling in a cell?

Accepted Answer

Using the energy released from ATP hydrolysis to drive the active transport of ions across a membrane.

Question 14

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

$$\Delta G = -10 - (300 	imes 0.02) = -16$$ kcal/mol

Question 15

Which of the following statements about ATP is correct?

Accepted Answer

ATP contains three phosphate groups, and hydrolysis of the terminal phosphate releases energy.

Question 16

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

Accepted Answer

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

Question 17

Which of the following is an example of an inorganic cofactor required for enzyme activity?

Accepted Answer

Zn$$^{2+}$$

Question 18

A scientist increases the substrate concentration in an enzyme-catalyzed reaction. What is the most likely effect on the reaction rate?

Accepted Answer

The reaction rate will increase until the enzyme becomes saturated, then level off.

Question 19

Which of the following best explains why organization in biological systems requires energy input?

Accepted Answer

Organization decreases entropy, which is nonspontaneous and requires energy.

Metabolism and Energy: Principles, Pathways, and Enzyme Regulation

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