Question 1

Which of the following statements best explains why the synthesis of macromolecules in living organisms requires an input of free energy?

Accepted Answer

Because the formation of macromolecules from simple precursors is a process that decreases entropy and thus requires energy input.

Question 2

Which of the following best describes the role of ATP in metabolism?

Accepted Answer

ATP acts as a universal energy currency by coupling the hydrolysis of its phosphoanhydride bonds to drive thermodynamically unfavorable reactions.

Question 3

Which of the following reactions is most likely to be used to synthesize ATP in cells, based on the standard free energy of hydrolysis?

Accepted Answer

Phosphoenolpyruvate (PEP) hydrolysis

Question 4

A metabolic pathway contains a reaction with a positive $$\Delta G^\circ'$$ value. How can this reaction proceed in the cell?

Accepted Answer

By coupling it to a reaction with a larger negative $$\Delta G^\circ'$$ value, such as ATP hydrolysis.

Question 5

Which of the following best explains why fats are a more efficient food source than glucose?

Accepted Answer

Fats are more reduced than glucose, so their oxidation releases more free energy.

Question 6

Which of the following is NOT a function of ATP in the cell?

Accepted Answer

Storing genetic information

Question 7

During a 100-meter sprint, which molecule is primarily responsible for regenerating ATP after the initial stores are depleted?

Accepted Answer

Creatine phosphate

Question 8

Which of the following statements about catabolism and anabolism is correct?

Accepted Answer

Catabolism involves oxidation and produces ATP, while anabolism involves reduction and consumes ATP.

Question 9

Which of the following best describes the role of NAD+ in metabolism?

Accepted Answer

NAD+ acts as an activated carrier of electrons for fuel oxidation.

Question 10

Which of the following is true regarding the hydrolysis of acetyl-CoA?

Accepted Answer

It is a strongly favorable reaction due to the high-energy thioester bond, with $$\Delta G^\circ' = -31.4 kJ/$$mol.

Question 11

Which of the following best explains why ATP is considered to have an intermediate phosphoryl transfer potential?

Accepted Answer

ATP can accept phosphate from compounds with higher $$\Delta G^\circ'$$ and donate phosphate to those with lower $$\Delta G^\circ'$$ values.

Question 12

Which of the following is an example of an activated carrier of electrons for biosynthetic reactions?

Accepted Answer

NADPH

Question 13

A patient is unable to efficiently oxidize fatty acids. Which of the following consequences is most likely?

Accepted Answer

Decreased production of acetyl-CoA and reduced ATP generation during fasting.

Question 14

Which of the following best describes the fate of carbon atoms from glucose during aerobic metabolism?

Accepted Answer

They are oxidized to CO$$_2$$ and the electrons are transferred to O$$_2 to $$form H$$_2O.$$

Question 15

Which of the following is a requirement for constructing a metabolic pathway?

Accepted Answer

The pathway as a whole must be thermodynamically favorable, and individual reactions must be specific.

Question 16

Which of the following best explains why the hydrolysis of thioesters, such as acetyl-CoA, is strongly favorable?

Accepted Answer

Thioesters lack resonance stabilization, so their hydrolysis releases a large amount of free energy.

Question 17

Which of the following statements about the ATP–ADP cycle is correct?

Accepted Answer

ATP is regenerated from ADP primarily by the oxidation of fuel molecules or by photosynthesis.

Question 18

Which of the following is a correct statement about the coupling of reactions in metabolism?

Accepted Answer

Thermodynamically unfavorable reactions can proceed if coupled to a reaction with a more negative $$\Delta G^\circ'$$ value.

Question 19

Which of the following best describes the role of coenzyme A (CoA-SH) in metabolism?

Accepted Answer

It acts as an activated carrier of two-carbon (acyl) groups.

Basic Concepts of Metabolism: Biochemistry Study Guide

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