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 building complex structures decreases entropy, which is only possible when energy is spent.

Question 2

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

Accepted Answer

ATP is the universal currency of free energy, coupling energy-yielding and energy-requiring reactions.

Question 3

Which of the following reactions is most likely to be used to drive a thermodynamically unfavorable reaction in a metabolic pathway?

Accepted Answer

$$\mathrm{ATP + H_2O \Longrightarrow ADP + P_i}$$

Question 4

Why are fats considered a more efficient food source than glucose?

Accepted Answer

Fats are more reduced than glucose, releasing more free energy upon oxidation.

Question 5

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

Accepted Answer

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

Question 6

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

Accepted Answer

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

Question 7

Which of the following compounds has the highest standard free energy of hydrolysis ($$\Delta G$$^{\circ'}$$)?

Accepted Answer

Phosphoenolpyruvate (PEP)

Question 8

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

Accepted Answer

Creatine phosphate

Question 9

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

Accepted Answer

The pathway as a whole must be thermodynamically favorable.

Question 10

Which of the following best explains why ATP is considered an energy-rich molecule?

Accepted Answer

It contains two phosphoanhydride linkages in its triphosphate unit.

Question 11

Which of the following statements about NAD$$^+$$ and NADP$$^+ is $$correct?

Accepted Answer

Both NAD$$^+$$ and NADP$$^+$$ have the same reactive site and can dissociate from enzymes after the reaction.

Question 12

Which of the following reactions is most likely to be coupled with the hydrolysis of ATP to drive it forward?

Accepted Answer

A reaction with a positive $$\Delta G$$^{\circ'}$$

Question 13

Which of the following best describes the fate of carbon atoms in fuels during catabolism?

Accepted Answer

They are oxidized to yield CO$$_2$$, and the electrons are accepted by oxygen to form H$$_2O.$$

Question 14

Which of the following is an example of an activated carrier of electrons for fuel oxidation?

Accepted Answer

NADH

Question 15

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

Accepted Answer

Thioesters have less resonance stabilization than oxygen esters, making their hydrolysis release more energy.

Question 16

A patient is unable to efficiently regenerate ATP during intense exercise. Which molecule is most likely deficient?

Accepted Answer

Creatine phosphate

Question 17

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

Accepted Answer

Catabolism involves oxidation and produces energy in biologically useful forms.

Question 18

Which of the following is a correct statement about the transfer of phosphate groups in metabolism?

Accepted Answer

Phosphate can be transferred from compounds with higher $$\Delta G$$^{\circ'}$$ to those with lower $$\Delta $$G^{\circ'}.$$

Question 19

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

Accepted Answer

It provides electrons for biosynthetic (anabolic) reactions.

Basic Concepts of Metabolism in Biochemistry

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