Question 1

Which of the following statements best describes the difference between catabolism and anabolism in microbial metabolism?

Accepted Answer

Catabolism is the energy-releasing process that breaks down molecules, while anabolism is the energy-consuming process that builds cellular material.

Question 2

A chemolithotrophic bacterium oxidizes hydrogen sulfide ($$H_2S) $$for energy and uses $$CO_2 as $$its carbon source. Which classification best fits this organism?

Accepted Answer

Chemolithoautotroph

Question 3

Which of the following is TRUE regarding enzymes in microbial metabolism?

Accepted Answer

Enzymes lower the activation energy of a reaction but do not affect the overall energetics or equilibrium.

Question 4

In the context of glycolysis, what is substrate-level phosphorylation?

Accepted Answer

The direct transfer of a phosphate group from an energy-rich organic compound to ADP, forming ATP.

Question 5

Which of the following is a correct equation for the reduction of NAD+ to NADH?

Accepted Answer

$$NAD^+ + H^+ + 2e^- \rightarrow NADH$$

Question 6

Which of the following statements about the electron transport chain (ETC) in eukaryotes is correct?

Accepted Answer

NADH is the most important electron donor, and molecular oxygen ($$O_2) is $$the final electron acceptor.

Question 7

A microorganism stores energy long-term in the form of poly-β-hydroxybutyrate. What is the primary function of this polymer?

Accepted Answer

It acts as a long-term energy reserve that can be oxidized to generate ATP.

Question 8

During aerobic respiration in prokaryotes, what is the main consequence of electron transport across the cytoplasmic membrane?

Accepted Answer

Generation of a pH gradient and an electrochemical potential (proton motive force) across the membrane.

Question 9

Which of the following is NOT a possible terminal electron acceptor in anaerobic respiration?

Accepted Answer

Oxygen ($$O_2)$$

Question 10

Which statement best explains why chemolithotrophs are typically autotrophic?

Accepted Answer

They use inorganic chemicals as electron donors and $$CO_2 as $$their carbon source.

Question 11

Which of the following best describes the role of cytochromes in the electron transport chain?

Accepted Answer

They are proteins containing heme groups that accept and donate electrons.

Question 12

A patient presents with lactic acidosis after intense exercise. Which metabolic pathway is primarily responsible for the accumulation of lactic acid?

Accepted Answer

Fermentation

Question 13

Which of the following is a correct description of photophosphorylation?

Accepted Answer

ATP synthesis mediated by light energy.

Question 14

Which of the following statements about prosthetic groups and coenzymes is correct?

Accepted Answer

Prosthetic groups are tightly bound, often covalently, while coenzymes are loosely bound and often derived from vitamins.

Question 15

Which of the following metabolic types would you expect to find in a bacterium living in deep-sea hydrothermal vents, oxidizing $$H_2$$ and using $$CO_2 as $$its carbon source?

Accepted Answer

Chemolithoautotroph

Question 16

Which process generates the most ATP per molecule of glucose in microorganisms?

Accepted Answer

Aerobic respiration

Question 17

What is the main function of the proton motive force generated by the electron transport chain?

Accepted Answer

To drive the synthesis of ATP via ATPase.

Question 18

Which of the following is a key difference between fermentation and respiration in microorganisms?

Accepted Answer

Fermentation involves both electron donation and acceptance by organic compounds, while respiration uses an external electron acceptor.

Question 19

Which biosynthetic pathway is responsible for the synthesis of glucose from non-carbohydrate precursors in microorganisms?

Accepted Answer

Gluconeogenesis

Microbial Metabolism: Foundations and Pathways

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