Question 1

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

Accepted Answer

Catabolism involves the breakdown of molecules to release energy, while anabolism uses energy to build macromolecules.

Question 2

In the redox reaction $$\mathrm{C_6H_{12}O_6$} + 6\ \mathrm{O_2$} \rightarrow 6\ \mathrm{CO_2$} + 6\ \mathrm{H_2O}$$, which molecule is oxidized and which is reduced?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} is $$oxidized and $$\mathrm{O_2$} is $$reduced.

Question 3

Which of the following is a primary function of NAD+ in cellular metabolism?

Accepted Answer

It serves as a freely diffusible electron carrier, cycling between oxidized and reduced forms.

Question 4

During glycolysis, which step involves substrate-level phosphorylation?

Accepted Answer

The conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate.

Question 5

Which of the following best explains why fermentation yields less ATP than aerobic respiration?

Accepted Answer

Fermentation only uses substrate-level phosphorylation and does not utilize an electron transport chain.

Question 6

Which of the following is a correct description of oxidative phosphorylation?

Accepted Answer

ATP is synthesized as protons flow through ATP synthase, driven by a proton motive force generated by the electron transport chain.

Question 7

A bacterium is growing anaerobically and produces ethanol and CO2 as waste products. Which metabolic pathway is it most likely using?

Accepted Answer

Alcohol fermentation

Question 8

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

Accepted Answer

The ETC transfers electrons from NADH and FADH2 to a terminal electron acceptor, generating a proton gradient.

Question 9

Which of the following is a key difference between anoxygenic and oxygenic photosynthesis?

Accepted Answer

Oxygenic photosynthesis produces oxygen as a byproduct, while anoxygenic does not.

Question 10

Which of the following best describes the role of the proton motive force in cellular energy production?

Accepted Answer

It drives the synthesis of ATP by ATP synthase as protons flow back across the membrane.

Question 11

Which of the following is a product of the citric acid cycle that directly donates electrons to the electron transport chain?

Accepted Answer

NADH

Question 12

A microorganism is capable of using inorganic compounds as an energy source and CO2 as a carbon source. How would you classify this organism?

Accepted Answer

Chemolithoautotroph

Question 13

Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA, linking glycolysis to the citric acid cycle?

Accepted Answer

Pyruvate dehydrogenase complex

Question 14

Which of the following is a correct statement about the Calvin-Benson cycle?

Accepted Answer

It is the main pathway for CO2 fixation in oxygenic phototrophs.

Question 15

Which of the following is a key enzyme in the reductive acetyl-CoA (Wood–Ljungdahl) pathway used by acetogens?

Accepted Answer

Carbon monoxide dehydrogenase

Question 16

Methanogenesis is a process unique to which group of microorganisms?

Accepted Answer

Archaea

Question 17

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is synthesized by the direct transfer of a phosphate group from a high-energy intermediate to ADP.

Question 18

Which of the following is a function of carotenoids in photosynthetic organisms?

Accepted Answer

They absorb blue light and protect cells from toxic oxygen species.

Question 19

In the context of syntrophy, why is the presence of a methanogen important for Syntrophomonas fermenting butyrate?

Accepted Answer

Methanogens consume H2 produced by Syntrophomonas, making the fermentation of butyrate energetically favorable.

Microbial Metabolism: Electron Flow and Energy Production

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