Question 1

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

Accepted Answer

Catabolic reactions release energy by breaking down molecules, while anabolic reactions use energy to build complex molecules.

Question 2

A chemoorganotroph obtains energy from which of the following sources?

Accepted Answer

Organic chemicals such as glucose

Question 3

During aerobic respiration, which molecule acts as the terminal electron acceptor in the electron transport chain?

Accepted Answer

$$\mathrm{O_2$}$$

Question 4

Which of the following equations correctly represents the overall reaction for aerobic respiration of glucose?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\ \mathrm{O_2$} \rightarrow 6\ \mathrm{CO_2$} + 6\ \mathrm{H_2O}$$

Question 5

In the context of redox reactions, what is the role of an electron donor?

Accepted Answer

It is the substance that is oxidized in the reaction.

Question 6

Which of the following best explains why ATP is considered the 'energy currency' of the cell?

Accepted Answer

ATP stores energy in its high-energy phosphate bonds, which can be used to drive cellular work.

Question 7

During glycolysis, what is the net gain of ATP molecules per molecule of glucose?

Accepted Answer

2 ATP

Question 8

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation produces ATP via substrate-level phosphorylation.

Question 9

In the citric acid cycle (CAC), what is the main function with respect to energy metabolism?

Accepted Answer

To completely oxidize pyruvate to $$\mathrm{CO_2$}$$ and generate NADH and FADH$$_2$$ for the electron transport chain.

Question 10

Which of the following best describes the proton motive force (PMF) in cellular respiration?

Accepted Answer

A gradient of protons (H$$^+) $$across the membrane, creating both a pH and electrical potential difference.

Question 11

Which enzyme complex is responsible for converting the proton motive force into ATP?

Accepted Answer

ATP synthase (ATPase)

Question 12

A bacterium is growing on acetate as its sole carbon source. Which metabolic pathway is especially important for this organism to generate biosynthetic precursors?

Accepted Answer

Glyoxylate cycle

Question 13

Which of the following statements about electron carriers is TRUE?

Accepted Answer

Electron carriers can be either prosthetic groups or diffusible coenzymes such as NAD$$^+.$$

Question 14

A mutation in the gene encoding ATP synthase (ATPase) would most directly affect which cellular process?

Accepted Answer

The conversion of the proton motive force into ATP.

Question 15

Which of the following best explains why the citric acid cycle is considered amphibolic?

Accepted Answer

It plays a role in both catabolism (energy production) and anabolism (biosynthesis of precursors).

Question 16

Which of the following is a correct statement about the energy yield of fermentation compared to aerobic respiration?

Accepted Answer

Fermentation yields less ATP per glucose than aerobic respiration.

Question 17

A patient is diagnosed with a genetic disorder that impairs the function of NAD$$^+ in $$their cells. Which metabolic process would be most directly affected?

Accepted Answer

The transfer of electrons during glycolysis and the citric acid cycle.

Question 18

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a phosphorylated intermediate.

Question 19

In a scenario where a bacterium switches from aerobic respiration to fermentation due to lack of oxygen, which of the following changes would you expect?

Accepted Answer

Decreased ATP yield per glucose molecule.

Question 20

Which of the following best explains why the inside of the membrane becomes electrically negative and alkaline during electron transport?

Accepted Answer

Protons (H$$^+) $$are pumped out of the cell, leaving behind negatively charged ions and increasing pH inside.

L4 Microbial Metabolism: Fundamentals, Energy, and Electron Transfer

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