Question 1

Which of the following best describes the role of enzymes in microbial metabolism?

Accepted Answer

Enzymes act as biological catalysts, lowering the activation energy and accelerating reactions.

Question 2

A microbe oxidizes Fe$^{2+}$ to Fe$^{3+}$ in the presence of oxygen. Which equation best represents this process?

Accepted Answer

$\mathrm{Fe^{2+} + H^+ + \frac{1}{4}O_2 \rightarrow Fe^{3+} + \frac{1}{2}H_2O}$

Question 3

Which of the following statements about entropy ($S$) and free energy ($\Delta G$) is correct?

Accepted Answer

An increase in entropy ($S$) results in a negative $\Delta G$, making the reaction favorable.

Question 4

Which of the following is a correct description of chemolithoautotrophs?

Accepted Answer

They obtain energy from the oxidation of inorganic chemicals and carbon from CO$_2$.

Question 5

Which of the following best explains why the electron transport system (ETS) is important for microbial energy conservation?

Accepted Answer

It generates a proton motive force (PMF) used to synthesize ATP.

Question 6

Which of the following is true regarding oxidative phosphorylation?

Accepted Answer

It involves ATP synthesis driven by an ion-motive force across a membrane.

Question 7

A bacterium is growing in an environment without oxygen but is still able to respire. Which of the following statements is most accurate?

Accepted Answer

The bacterium is performing anaerobic respiration using alternative electron acceptors such as NO$_3^-$ or SO$_4^{2-}$.

Question 8

Which of the following best describes the function of NAD$^+$ in cellular metabolism?

Accepted Answer

NAD$^+$ acts as an oxidant, accepting electrons and becoming reduced to NADH.

Question 9

Which of the following equations correctly relates enthalpy ($\Delta H$), free energy ($\Delta G$), and entropy ($\Delta S$)?

Accepted Answer

$\Delta H = \Delta G + T\Delta S$

Question 10

Which of the following is a key difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation couples ATP synthesis to the breakdown of high-energy metabolites, while oxidative phosphorylation uses a proton motive force.

Question 11

Which of the following statements about redox potential is correct?

Accepted Answer

A negative redox potential means the oxidized form is more stable.

Question 12

Which of the following is NOT a function of the proton motive force (PMF) in microbial cells?

Accepted Answer

Directly synthesizing DNA from nucleotides.

Question 13

Which of the following best describes the process of photophosphorylation?

Accepted Answer

ATP synthesis driven by a photon-induced proton motive force.

Question 14

A microbe is classified as a chemoheterotroph. Which of the following statements is true?

Accepted Answer

It uses organic compounds as both an energy and carbon source.

Question 15

Which of the following is a benefit of catabolism in microbial cells?

Accepted Answer

Production of reducing power such as NADH.

Question 16

Which of the following is true about electron carriers in the electron transport system (ETS)?

Accepted Answer

Some carriers, such as cytochromes, only accept electrons.

Question 17

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

Accepted Answer

$\mathrm{NAD^+ + 2e^- + 2H^+ \rightarrow NADH + H^+}$

Question 18

Which of the following best explains why free electrons do not exist in nature in biological systems?

Accepted Answer

Electrons are transferred via carriers such as NADH and cytochromes.

Question 19

Which of the following is a real-world example of microbial energy conservation involving methanogenic archaea?

Accepted Answer

CO$_2$ is reduced by H$_2$ to produce CH$_4$ and H$_2$O.

Lectures 16, 17

Study Guide - Practice Questions

Study Guide - Flashcards