Question 1

Which of the following features is unique to archaeal cell membranes compared to those of bacteria and eukaryotes?

Accepted Answer

Presence of ether-linked phospholipids

Question 2

Which adaptation allows hyperthermophilic archaea to maintain membrane integrity at temperatures above 100 °C?

Accepted Answer

Formation of a lipid monolayer

Question 3

Methanobrevibacter smithii improves digestive efficiency in humans primarily by:

Accepted Answer

Removing hydrogen produced by bacterial fermentation

Question 4

Which feature most strongly supports the conclusion that archaea are evolutionarily closer to eukaryotes than to bacteria?

Accepted Answer

Use of histone proteins in DNA packaging

Question 5

The primary adaptive advantage of ether-linked lipids in archaeal membranes is that they:

Accepted Answer

Resist chemical hydrolysis and thermal degradation

Question 6

Which enzyme is unique to hyperthermophilic archaea and helps protect their DNA from denaturation at high temperatures?

Accepted Answer

Reverse gyrase

Question 7

Which group of archaea is most closely related to eukaryotes based on genetic analysis?

Accepted Answer

Asgard archaea

Question 8

Why are archaeal enzymes particularly valuable in lactose-free milk production?

Accepted Answer

They remain active at pasteurization temperatures

Question 9

Using archaeal β-galactosidase during pasteurization improves food safety because:

Accepted Answer

High temperatures suppress contaminating microbes

Question 10

Which of the following best describes the role of salt bridges in archaeal proteins?

Accepted Answer

They act as molecular staples, stabilizing protein structure at high temperatures

Question 11

Which archaeal group is characterized by extremely small cell and genome size, often requiring a symbiotic lifestyle?

Accepted Answer

DPANN group

Question 12

Which adaptation allows hyperthermophilic archaea to refold denatured proteins and maintain cellular function at high temperatures?

Accepted Answer

Thermosome chaperonin complex

Question 13

Which of the following is NOT a known habitat for archaea?

Accepted Answer

Obligate intracellular parasites of humans

Question 14

Which of the following statements about archaeal pathogens is correct?

Accepted Answer

No archaeal species has been confirmed as a pathogen

Question 15

Which archaeal group is responsible for methane production in oxygen-free environments such as wetlands and the human gut?

Accepted Answer

Methanogens

Question 16

Which of the following best explains why high levels of Methanobrevibacter smithii are associated with chronic constipation?

Accepted Answer

Methane gas slows intestinal transit time

Question 17

Which of the following is a major role of Thaumarchaeota in the environment?

Accepted Answer

Nitrogen cycling

Question 18

Which of the following is a key reason why archaeal β-galactosidase is preferred over bacterial β-galactosidase for industrial lactose hydrolysis during pasteurization?

Accepted Answer

Archaeal enzyme is not denatured at high temperatures

Question 19

Which of the following best describes the function of histone proteins in archaea?

Accepted Answer

They package DNA into compact, protected structures

Question 20

Which of the following is a defining feature of the Asgard archaea?

Accepted Answer

They contain genes for complex cellular processes previously thought unique to eukaryotes

Archaea: Structure, Adaptations, and Roles in Microbiology

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