Question 1

Which of the following best describes catabolic reactions in microbial metabolism?

Accepted Answer

Energy-releasing metabolic reactions that break down complex molecules into simpler ones.

Question 2

A cell is performing an exergonic reaction. Which statement is TRUE about this process?

Accepted Answer

The reaction releases free energy that can be used to do work.

Question 3

Which of the following is NOT a requirement for microbial growth?

Accepted Answer

Oxygen as the only electron acceptor

Question 4

In a redox reaction, the electron donor is:

Accepted Answer

The substance that is oxidized in the reaction.

Question 5

Given the following redox couples: $$NAD^+ / NADH$$ ($$E_0$$' = -320$$ mV) and $$FAD / $$FADH_2$$ ($$E_0$$' = -219$$ mV), which is the stronger electron donor?

Accepted Answer

NADH because it has a more negative $$E_0$$'$$ value.

Question 6

Which class of microorganism uses inorganic chemicals as its energy source?

Accepted Answer

Chemolithotrophs

Question 7

What is the main function of the electron transport chain in microbial respiration?

Accepted Answer

To mediate the transfer of electrons and conserve energy for ATP synthesis.

Question 8

Which of the following statements about substrate-level phosphorylation is TRUE?

Accepted Answer

It involves the direct transfer of a phosphate group to ADP to form ATP.

Question 9

During aerobic respiration, what is the terminal electron acceptor?

Accepted Answer

Oxygen ($$O_2)$$

Question 10

Why does anaerobic respiration generally release less energy than aerobic respiration?

Accepted Answer

The terminal electron acceptors in anaerobic respiration have less positive $$E_0$$'$$ values than O_2$.

Question 11

Which of the following is TRUE about fermentation in microorganisms?

Accepted Answer

Organic compounds serve as both electron donors and acceptors.

Question 12

What is the role of NAD$$^+ in $$microbial metabolism?

Accepted Answer

It serves as an electron carrier, cycling between oxidized (NAD$$^+) $$and reduced (NADH) forms.

Question 13

Which process is catalyzed by the enzyme nitrogenase?

Accepted Answer

Reduction of nitrogen gas ($$N_2) to $$ammonia ($$NH_3)$$

Question 14

Which of the following best explains the function of the proton motive force in microbial cells?

Accepted Answer

It is used to synthesize ATP via ATP synthase.

Question 15

A mutation disables the cytochrome proteins in a bacterium. What is the most likely consequence?

Accepted Answer

The cell's electron transport chain will be disrupted, reducing ATP production.

Question 16

Which of the following is a real-world example of a chemolithotroph?

Accepted Answer

Thiobacillus thiooxidans oxidizing sulfur compounds.

Question 17

Which statement about enzymes is CORRECT?

Accepted Answer

Enzymes lower the activation energy, increasing the rate of reaction.

Question 18

Which of the following is TRUE about the active site of an enzyme?

Accepted Answer

It is the region where substrates bind and the reaction occurs.

Question 19

A bacterium is growing in an environment with no oxygen but abundant nitrate ($$NO_3$$^-$$). Which metabolic process is most likely occurring?

Accepted Answer

Anaerobic respiration using nitrate as the terminal electron acceptor

Question 20

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

Accepted Answer

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

Microbial Metabolism: Energy, Electron Flow, and Metabolic Diversity

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