Question 1

Which of the following statements best describes the relationship between standard redox potential ($$E_0$$'$$) and the ability of a molecule to act as an electron donor or acceptor?

Accepted Answer

A molecule with a more negative $$E_0$$'$$ is a better electron donor.

Question 2

During aerobic respiration, NADH donates electrons to oxygen. Given the standard redox potentials $$E_0$$'$$ for NADH (-0.32$ V) and O_2$ (+0.815$ V), what is the change in standard reduction potential ($$\Delta $$E_0$$'$$) for this reaction?

Accepted Answer

$$\Delta E_0$' = +1.14 V$$

Question 3

Which equation correctly relates the change in Gibbs free energy ($$\Delta G^\circ') to $$the change in standard reduction potential ($$\Delta E_0$'$$)?

Accepted Answer

$$\Delta G^\circ' = -nF\Delta E_0$'$$

Question 4

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

Accepted Answer

2 ATP

Question 5

Which of the following best explains why ATP hydrolysis is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases free energy ($$\Delta G^\circ' = -7.3$$ kcal/mol), making endergonic reactions more favorable.

Question 6

A bacterium oxidizes hydrogen sulfide ($$H_2S) $$using oxygen as the terminal electron acceptor. What type of metabolism is this?

Accepted Answer

Chemolithotrophy

Question 7

Which of the following is a correct summary of the products generated per glucose molecule after the citric acid cycle (Krebs cycle) is completed?

Accepted Answer

6 CO$$_2$$, 8 NADH, 2 FADH$$_2$$, 2 GTP (or ATP)

Question 8

Which of the following best describes the fate of NADH produced during glycolysis under anaerobic conditions?

Accepted Answer

NADH donates electrons to an organic molecule derived from pyruvate during fermentation.

Question 9

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

Accepted Answer

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

Question 10

A mutation in a bacterium prevents the regeneration of NAD$$^+. $$Which metabolic process would be most directly affected?

Accepted Answer

Glycolysis

Question 11

Which of the following is NOT a characteristic shared by all microbial metabolic pathways?

Accepted Answer

All reactions are spontaneous and exergonic.

Question 12

Which of the following best explains why the citric acid cycle produces more ATP than fermentation?

Accepted Answer

The citric acid cycle completely oxidizes pyruvate to CO$$_2$$, generating more NADH and FADH$$_2$$ for the electron transport chain.

Question 13

Which of the following is a correct description of a conjugate redox pair?

Accepted Answer

An electron donor and its corresponding oxidized or reduced form.

Question 14

A patient is diagnosed with a genetic disorder that impairs the function of the electron transport chain. Which of the following would most likely be observed in their cells?

Accepted Answer

Decreased ATP production and accumulation of NADH.

Question 15

Which of the following best describes the role of NAD$$^+/$$NADH in cellular metabolism?

Accepted Answer

They act as electron carriers, shuttling electrons between metabolic reactions.

Question 16

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

Accepted Answer

Thiobacillus oxidizing $$H_2S to$$ $$SO_4$$^{2-}$$ for energy.

Question 17

Which of the following best explains why the breakdown of glucose via glycolysis and the citric acid cycle is considered exergonic?

Accepted Answer

The overall $$\Delta G^\circ'$$ for the combined reactions is negative, indicating a release of free energy.

Question 18

Which of the following is true regarding the fate of pyruvate in microbial metabolism?

Accepted Answer

It can be completely oxidized to CO$$_2$$ via the citric acid cycle or reduced to various products during fermentation.

Question 19

Which of the following best describes the main difference between chemoorganotrophs and chemolithotrophs?

Accepted Answer

Chemoorganotrophs use organic compounds as electron donors, while chemolithotrophs use inorganic compounds.

Microbial Metabolism: Redox Reactions, Energy Conservation, and Central Metabolic Pathways

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