Question 1

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

Accepted Answer

Catabolic reactions are degradative and release energy (ATP), while anabolic reactions require energy (ATP investment) to build cellular components.

Question 2

During glycolysis, how many net ATP molecules are produced per molecule of glucose via substrate-level phosphorylation?

Accepted Answer

$2$

Question 3

Which statement correctly explains the role of NADH in fermentation?

Accepted Answer

NADH is oxidized to regenerate NAD$^+$, allowing glycolysis to continue in the absence of an electron transport chain.

Question 4

A bacterial mutant is deficient in heme biosynthesis (SCV mutant). Which metabolic pathway is most likely impaired in this mutant?

Accepted Answer

Aerobic respiration

Question 5

Which of the following equations correctly represents the net reaction of aerobic respiration using glucose as the electron donor and oxygen as the terminal electron acceptor?

Accepted Answer

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

Question 6

In the context of the redox tower, which combination of electron donor and acceptor yields the most energy for the cell?

Accepted Answer

Hydrogen ($\mathrm{H_2}$) as donor and oxygen ($\mathrm{O_2}$) as acceptor

Question 7

Which process directly generates ATP by transferring a phosphate group from a high-energy substrate to ADP?

Accepted Answer

Substrate-level phosphorylation

Question 8

A facultative anaerobe is grown in a thioglycolate broth. Where would you expect to see the highest density of growth?

Accepted Answer

Throughout the tube, but more concentrated near the top

Question 9

Which of the following is a correct description of oxidative phosphorylation?

Accepted Answer

ATP is generated using energy from a proton gradient created by the electron transport chain.

Question 10

Which of the following statements about the electron transport chain (ETC) in bacteria is TRUE?

Accepted Answer

The ETC creates a proton gradient across the membrane, which is used to synthesize ATP.

Question 11

A microbe is classified as a mesophile. What is its optimal temperature range for growth?

Accepted Answer

$20^{\circ}\mathrm{C}$ - $45^{\circ}\mathrm{C}$

Question 12

Which of the following is a major reason why autoclaving is effective for sterilization?

Accepted Answer

It uses steam under pressure to reach temperatures above $100^{\circ}\mathrm{C}$, killing all microbes including spores.

Question 13

Which of the following is the correct sequence of events in the Central Dogma of molecular biology?

Accepted Answer

DNA $\rightarrow$ RNA $\rightarrow$ Protein

Question 14

Which of the following best explains why some bacteria can use nitrate ($\mathrm{NO_3^-}$) as a terminal electron acceptor instead of oxygen?

Accepted Answer

They possess alternative ETC enzymes and are present in environments lacking oxygen.

Question 15

Which of the following is a consequence of exposing a mesophilic bacterium to temperatures above its maximum growth temperature?

Accepted Answer

Enzymes and membranes will denature, leading to cell death.

Question 16

Which of the following is a correct example of a redox reaction in cellular metabolism?

Accepted Answer

$\mathrm{H_2} + \frac{1}{2}\mathrm{O_2} \rightarrow \mathrm{H_2O}$, where $\mathrm{H_2}$ is oxidized and $\mathrm{O_2}$ is reduced.

Question 17

Which of the following is a key requirement for a bacterium to perform aerobic respiration?

Accepted Answer

Presence of genes encoding ETC enzymes and a terminal electron acceptor (oxygen).

Question 18

A bacterial culture is exposed to a sudden decrease in water availability. What is the most likely immediate effect on microbial growth?

Accepted Answer

Growth rate will decrease or stop due to inhibition of enzymatic and transport processes.

Question 19

Which of the following best describes the function of electron carriers such as NAD$^+$ and FAD in metabolism?

Accepted Answer

They transfer electrons between metabolic pathways, facilitating redox reactions.

Microbial Metabolism: Bioenergetics, Fermentation, and Respiration

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