Question 1

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

Accepted Answer

They are energy-releasing metabolic reactions that break down complex molecules.

Question 2

A cell is performing an exergonic reaction. Which statement is true about the change in free energy ($\Delta G^\circ'$) for this reaction?

Accepted Answer

$\Delta G^\circ'$ is negative, indicating energy is released.

Question 3

Which of the following is NOT a requirement for all microbial cells?

Accepted Answer

Oxygen

Question 4

In a redox reaction, which statement correctly describes the electron donor?

Accepted Answer

It loses electrons and is oxidized.

Question 5

Given the following reduction potentials: $E^\circ'_{NADH} = -320\ 	ext{mV}$ and $E^\circ'_{FADH_2} = -220\ 	ext{mV}$, which is the stronger electron donor and why?

Accepted Answer

NADH is stronger because its $E^\circ'$ is more negative.

Question 6

Which of the following best explains why less energy is released during anaerobic respiration compared to aerobic respiration?

Accepted Answer

Anaerobic respiration uses electron acceptors with lower reduction potentials than oxygen.

Question 7

Which of the following compounds is considered energy-rich due to its high phosphoryl transfer potential?

Accepted Answer

Phosphoenolpyruvate (PEP)

Question 8

What is the primary function of ATP synthase (ATPase) in microbial cells?

Accepted Answer

To convert the proton motive force into ATP.

Question 9

Which statement about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of both exergonic and endergonic reactions.

Question 10

A bacterium is using nitrate ($NO_3^-$) as its terminal electron acceptor. Which metabolic process is it performing?

Accepted Answer

Anaerobic respiration

Question 11

Which of the following is true about substrate-level phosphorylation?

Accepted Answer

It involves the direct transfer of a phosphate group to ADP from a phosphorylated intermediate.

Question 12

During glycolysis, which molecule acts as the final electron acceptor?

Accepted Answer

NAD$^+$

Question 13

Which of the following statements about nitrogen fixation is correct?

Accepted Answer

It is catalyzed by the enzyme nitrogenase and inhibited by oxygen.

Question 14

Which of the following is a prosthetic group in enzymes?

Accepted Answer

Heme group in cytochromes

Question 15

A cell is using glucose as an electron donor and oxygen as an electron acceptor. What is the overall reaction?

Accepted Answer

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

Question 16

Which statement best describes the arrangement of electron carriers in the electron transport chain?

Accepted Answer

They are arranged in order of their reduction potential.

Question 17

Which of the following is a real-world example of a symbiotic nitrogen-fixing relationship?

Accepted Answer

Rhizobium bacteria in root nodules of legumes

Question 18

Which process directly generates a proton gradient across the bacterial membrane?

Accepted Answer

Electron transport chain activity

Question 19

Which of the following statements about coenzymes is correct?

Accepted Answer

They are loosely bound and often derived from vitamins.

Question 20

A bacterium is growing in an environment lacking oxygen but rich in sulfate ($SO_4^{2-}$). Which metabolic process is most likely occurring?

Accepted Answer

Anaerobic respiration using $SO_4^{2-}$ as the electron acceptor

Microbial 3. Metabolism: Principles, Pathways, and Diversity

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