Question 1

Which of the following best describes a chemolithotroph?

Accepted Answer

An organism that uses inorganic compounds as its energy and electron source.

Question 2

In the electron transport chain of aerobic respiration in bacteria, what is the final electron acceptor?

Accepted Answer

Oxygen (O$$_2)$$

Question 3

Which of the following statements about fermentation is TRUE?

Accepted Answer

Fermentation relies on substrate-level phosphorylation to generate ATP.

Question 4

A bacterium is using nitrate as its terminal electron acceptor and NADH as its electron donor. Which process is this organism performing?

Accepted Answer

Anaerobic respiration

Question 5

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

Accepted Answer

Oxygenic photosynthesis uses water as the electron donor, producing O$$_2.$$

Question 6

Which pigment is primarily responsible for the blue-green color of cyanobacteria?

Accepted Answer

Phycobilins

Question 7

Why is magnesium considered a macronutrient for photosynthetic microbes?

Accepted Answer

It is a central atom in chlorophyll and bacteriochlorophyll molecules.

Question 8

Which of the following best explains why facultative organisms like Saccharomyces switch from aerobic respiration to fermentation in a closed beer fermentation tank?

Accepted Answer

Oxygen is depleted, so the organism switches to fermentation to continue ATP production.

Question 9

In the electron transport chain, what is the primary role of quinones?

Accepted Answer

To shuttle electrons and help pump protons across the membrane.

Question 10

Which of the following is TRUE regarding the Calvin-Benson cycle in photosynthetic organisms?

Accepted Answer

It fixes CO$$_2$$ into organic molecules using ATP and NADH produced during the light reactions.

Question 11

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

Accepted Answer

They absorb toxic oxygen species and act as photoprotective pigments.

Question 12

A microbe uses hydrogen as its electron donor and CO$$_2 as $$its carbon source. Which of the following best describes its metabolism?

Accepted Answer

Chemolithotrophic autotroph

Question 13

Which of the following statements about ATP synthase is CORRECT?

Accepted Answer

It synthesizes ATP by utilizing the proton (or sodium) motive force across a membrane.

Question 14

In anoxygenic photosynthesis, which of the following is NOT used as an electron donor?

Accepted Answer

Water (H$$_2O)$$

Question 15

Which process is responsible for the majority of oxygen in Earth's atmosphere?

Accepted Answer

Oxygenic photosynthesis by cyanobacteria and algae

Question 16

Methanogenesis is a process carried out by certain archaea. Which of the following statements is TRUE about methanogenesis?

Accepted Answer

It uses hydrogen as an electron donor and CO$$_2 as an $$electron acceptor.

Question 17

Which of the following best explains why reverse electron flow is necessary in some chemolithotrophs and anoxygenic phototrophs?

Accepted Answer

To reduce NAD$$^+ to $$NADH for biosynthetic reactions.

Question 18

Which of the following is a distinguishing feature of oxygenic photosynthesis compared to anoxygenic photosynthesis?

Accepted Answer

It uses water as the electron donor and produces O$$_2 as a $$byproduct.

Question 19

In the context of microbial metabolism, what is the main advantage of respiration over fermentation?

Accepted Answer

Respiration produces more ATP per glucose molecule than fermentation.

Question 20

Which of the following is TRUE about the location of photosynthetic pigments in prokaryotes?

Accepted Answer

They are embedded in or associated with the cytoplasmic membrane or specialized internal membranes.

Microbial Metabolism: Electron Transport, Respiration, and Photosynthesis

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