Question 1

Which of the following best describes the metabolic characteristics of most members of the phylum Bacteroidota?

Accepted Answer

Obligately anaerobic or fermentative

Question 2

Bacteroides species are dominant in the human gut microbiome. What is their primary ecological role in this environment?

Accepted Answer

Degradation of complex polysaccharides

Question 3

Which of the following statements about Cytophagales is correct?

Accepted Answer

They are gram-negative rods capable of gliding motility

Question 4

A fish farm experiences a sudden die-off of fish in polluted water. Which bacterial group is most likely involved as a pathogen in this scenario?

Accepted Answer

Cytophaga psychrophila

Question 5

Which of the following is a distinguishing feature of Flavobacteriales compared to other Bacteroidota?

Accepted Answer

Ability to degrade complex polysaccharides in marine environments

Question 6

Chlamydiae are unique among bacteria because they:

Accepted Answer

Are obligate intracellular parasites lacking peptidoglycan in their cell walls

Question 7

Which of the following best explains why Thermotogae, Desulfobacteria, and Aquificae are considered important for understanding early bacterial evolution?

Accepted Answer

They are positioned at the root of bacterial phylogenetic trees and are thermophilic

Question 8

Which of the following is a key difference between Archaea and Bacteria?

Accepted Answer

Archaea have ether-linked lipids in their membranes, while Bacteria have ester-linked lipids

Question 9

Methanogenic Archaea are critical in which of the following processes?

Accepted Answer

The terminal step of organic matter degradation in anaerobic environments

Question 10

Which environmental condition is required for the growth of extreme halophilic Archaea?

Accepted Answer

High salt concentrations, typically above 9% NaCl

Question 11

A wastewater treatment plant relies on methanogenic Archaea for biogas production. Which of the following best describes the metabolic process involved?

Accepted Answer

Anaerobic conversion of organic matter to methane ($$CH_4) as $$the terminal step

Question 12

Which of the following statements about the Euryarchaeota is correct?

Accepted Answer

They include methanogens, extreme halophiles, and thermophiles

Question 13

Which of the following best describes the cell envelope diversity among methanogenic Archaea?

Accepted Answer

They are polyphyletic and exhibit a diversity of cell envelope configurations

Question 14

A researcher isolates a microorganism from a self-heating compost pile that grows optimally at 60°C and degrades organic acids. To which group does this organism most likely belong?

Accepted Answer

Thermoplasmatales

Question 15

Which of the following is a defining feature of the hydrogenosome found in some eukaryotes such as Trichomonas vaginalis?

Accepted Answer

It produces ATP via fermentation and releases $$H_2$$ and acetate

Question 16

Giardia intestinalis is notable for which of the following cellular features?

Accepted Answer

It has two nuclei of equal size and lacks typical mitochondria

Question 17

Which of the following best explains why the SAR clade is not considered a single taxon?

Accepted Answer

It is a cluster of related phyla rather than a single monophyletic group

Question 18

A multicellular eukaryote forms a 'kelp forest' in a marine environment. To which major group does it most likely belong?

Accepted Answer

Stramenopiles

Question 19

Which of the following is a correct statement about the evolutionary relationship between Archaea and Eukarya?

Accepted Answer

Archaea share more in common with Eukarya than with Bacteria, including aspects of their polymerases

Question 20

Which of the following best describes the function of the anammoxosome in certain Planctomycetes?

Accepted Answer

It is an organelle that enables anaerobic ammonium oxidation using nitrite as an electron acceptor

Phylogenetic Diversity of Microorganisms: Bacteria, Archaea, and Eukarya

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