Question 1

Which of the following statements best describes the hydrolysis of ATP to ADP and inorganic phosphate ($$\mathrm{ADP} + \mathrm{P_i}$$)?

Accepted Answer

It is an exergonic reaction that releases free energy.

Question 2

A chemical reaction has $$\Delta G = +15\ \mathrm{kJ}$$, while ATP hydrolysis has $$\Delta G = -30.5\ \mathrm{kJ}. If $$these reactions are coupled, what is the overall $$\Delta G$$ and will the reaction proceed spontaneously?

Accepted Answer

Overall $$\Delta G = -15.5\ \mathrm{kJ}$$; the reaction will proceed spontaneously.

Question 3

Which of the following best explains how enzymes speed up chemical reactions?

Accepted Answer

They lower the activation energy ($$E_a) $$required for the reaction.

Question 4

A scientist is studying an enzyme that works best at pH 2. Where in the human body is this enzyme most likely to be found?

Accepted Answer

In the stomach

Question 5

Which of the following is an example of a competitive inhibitor?

Accepted Answer

A molecule that binds to the active site of an enzyme, blocking substrate binding.

Question 6

During cellular respiration, which molecule is oxidized and which is reduced in the following reaction? $$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} \rightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O}$$

Accepted Answer

Glucose is oxidized; oxygen is reduced.

Question 7

Which of the following best describes the role of NAD+ in cellular respiration?

Accepted Answer

It acts as a temporary electron acceptor, becoming reduced to NADH.

Question 8

A patient has a mutation that causes their enzymes to denature at 37°C. What is the most likely consequence for their metabolism?

Accepted Answer

Their metabolic reactions will slow down or stop at normal body temperature.

Question 9

Which of the following is true about feedback inhibition in metabolic pathways?

Accepted Answer

The end product of the pathway inhibits an enzyme that acts early in the pathway.

Question 10

In a redox reaction, what happens to the molecule that is reduced?

Accepted Answer

It gains electrons.

Question 11

Which of the following best describes the function of the electron transport chain in cellular respiration?

Accepted Answer

It transfers electrons from NADH and FADH2 to oxygen, producing water and generating a proton gradient.

Question 12

If an enzyme's active site contains acidic amino acids, what type of environment is likely optimal for its activity?

Accepted Answer

An acidic (low pH) environment

Question 13

Which of the following is a correct statement about the relationship between $$\Delta G$$ and spontaneity of a reaction?

Accepted Answer

A reaction with $$\Delta G \u003c 0 is $$spontaneous.

Question 14

Which of the following best describes the process of substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP.

Question 15

A noncompetitive inhibitor decreases the rate of an enzyme-catalyzed reaction by:

Accepted Answer

Binding to a different site on the enzyme, altering its conformation.

Question 16

During glycolysis, glucose is converted to pyruvate. Which of the following statements is true about this process?

Accepted Answer

It occurs in the cytosol and does not require oxygen.

Question 17

Which of the following best explains why the breakdown of glucose in cellular respiration occurs in multiple steps?

Accepted Answer

To ensure that energy is released slowly enough to be captured and used by the cell.

Question 18

If NADH is oxidized by oxygen at the end of cellular respiration, what molecule is formed?

Accepted Answer

NAD+

Question 19

Which of the following is a correct example of a redox reaction?

Accepted Answer

$$\mathrm{Na} + \mathrm{Cl} \rightarrow \mathrm{Na}^+ + \mathrm{Cl}^-$$, where Na is oxidized and Cl is reduced.

Question 20

Which of the following best describes the fate of energy in an ecosystem according to the study materials?

Accepted Answer

Energy enters as sunlight and leaves as heat.

Metabolism, Enzymes, and Energy Transformations in Cells

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