Question 1

Which of the following statements best describes the unique feature of archaeal plasma membranes compared to bacterial membranes?

Accepted Answer

Archaeal membranes contain ether-linked isoprenoid chains, which can form either a lipid bilayer or a monolayer.

Question 2

Which metabolic pathway is used by methanogens to produce methane, and what is the overall chemical equation for this process?

Accepted Answer

Methanogens use the Calvin cycle; $$ \mathrm{CO_2$ + 4H_2 \rightarrow CH_4$ + 2H_2O} $$

Question 3

Which adaptation allows hyperthermophilic Archaea to maintain DNA stability at high temperatures?

Accepted Answer

High C-G content in DNA, reverse gyrase, and DNA-stabilizing proteins.

Question 4

Which of the following is TRUE regarding the S-layer in Archaea?

Accepted Answer

It is a glycoprotein layer that serves as the main cell wall component in many Archaea.

Question 5

Halobacterium salinarum uses bacteriorhodopsin for phototrophy. What is the role of bacteriorhodopsin in energy generation?

Accepted Answer

It absorbs photons, changes retinal conformation, and pumps protons to generate a proton gradient for ATP synthesis.

Question 6

Which of the following best explains why Halobacterium thrives in high-salt environments?

Accepted Answer

It accumulates high internal potassium ion concentrations and has acidic proteins stabilized by potassium.

Question 7

Which statement best describes the transcription machinery in Archaea?

Accepted Answer

Archaeal RNA polymerase and general transcription factors are more similar to those of Eukarya than Bacteria.

Question 8

Which of the following is a key difference between archaeal and bacterial translation?

Accepted Answer

Archaea initiate translation with methionine, similar to Eukarya, while Bacteria use formylmethionine.

Question 9

Which metabolic pathway is NOT present in Archaea but is common in Bacteria?

Accepted Answer

Glycolysis via the Embden-Meyerhof-Parnas pathway.

Question 10

Which of the following best describes the function of reverse gyrase in hyperthermophilic Archaea?

Accepted Answer

It introduces positive supercoils into DNA, stabilizing it at high temperatures.

Question 11

Which of the following is a correct description of the cell wall structure in most Archaea?

Accepted Answer

It is composed of pseudopeptidoglycan (pseudomurein) or S-layer proteins.

Question 12

Which of the following best explains why Nanoarchaeum equitans is considered a parasite?

Accepted Answer

It lacks ATP synthase and depends on its host for energy.

Question 13

Which of the following is a unique feature of Thaumarchaeota compared to other Archaea?

Accepted Answer

They are capable of autotrophic ammonia oxidation using ammonia monooxygenase (AMO).

Question 14

Which of the following best describes the main energy-generating process in Halobacterium under low oxygen conditions?

Accepted Answer

Bacteriorhodopsin absorbs light, pumps protons, and generates ATP via ATP synthase.

Question 15

Which of the following is a correct statement about the genome organization in Archaea?

Accepted Answer

Archaeal genomes are circular, haploid, and genes are often organized in operons.

Question 16

Which of the following best describes the metabolic role of methanogens in the environment?

Accepted Answer

They reduce carbon dioxide to methane, often using hydrogen as an electron donor.

Question 17

Which of the following is a plausible reason why hyperthermophilic Archaea are found in marine hydrothermal vents?

Accepted Answer

They possess enzymes and membrane adaptations that allow survival at temperatures up to 110$$^\circC.$$

Question 18

Which of the following is a key difference between the photosynthetic systems of Halobacterium and Cyanobacteria?

Accepted Answer

Halobacterium uses bacteriorhodopsin and does not produce oxygen, while Cyanobacteria use chlorophyll and produce oxygen.

Question 19

Which of the following best describes the evolutionary significance of Asgardian Archaea?

Accepted Answer

They possess genes homologous to eukaryotic actin and tubulin, suggesting a close relationship to the origin of Eukarya.

Diversity and Molecular Biology of Archaea: Structure, Metabolism, and Adaptations chapter 17

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