Question 1

Which of the following statements best explains why viruses are not considered living organisms according to the major characteristics of life?

Accepted Answer

Viruses are not composed of cells.

Question 2

Which group of microorganisms includes both prokaryotic and eukaryotic members?

Accepted Answer

Protists

Question 3

A scientist is trying to classify a newly discovered microorganism. It is unicellular, lacks a nucleus, and its cell wall contains peptidoglycan. To which domain does this organism most likely belong?

Accepted Answer

Bacteria

Question 4

Which of the following is a unique feature of Gram-negative bacteria compared to Gram-positive bacteria?

Accepted Answer

Presence of an outer membrane containing lipopolysaccharides

Question 5

Which process allows bacteria to acquire new genetic material from their environment, potentially leading to increased diversity?

Accepted Answer

Horizontal gene transfer

Question 6

A bacterium is classified as a chemoautotroph. Which of the following best describes its sources of energy and carbon?

Accepted Answer

Inorganic compounds as energy source, CO$_2$ as carbon source

Question 7

Which of the following best describes the role of peptidoglycan in bacterial cells?

Accepted Answer

It provides structural strength to the cell wall.

Question 8

Why are most prokaryotes not easily classified by their metabolic characteristics alone?

Accepted Answer

Many prokaryotes cannot be cultured in the laboratory.

Question 9

Which of the following is a consequence of horizontal gene transfer in prokaryotes?

Accepted Answer

It causes phylogenetic trees to sometimes resemble webs rather than branches.

Question 10

A bacterium is found living in a highly acidic hot spring at 90$^	ext{o}$C. Which domain is it most likely to belong to?

Accepted Answer

Archaea

Question 11

Which of the following best explains why the majority of Earth's biodiversity is microbial?

Accepted Answer

Microbes can survive and adapt to extreme environments.

Question 12

Which method is most commonly used today to assess microbial diversity in an environmental sample without culturing?

Accepted Answer

16S rRNA gene sequencing

Question 13

Which of the following is NOT a characteristic of all living organisms?

Accepted Answer

Dependence on host cells for replication

Question 14

Which of the following statements about endospores is correct?

Accepted Answer

Endospores are highly resistant to environmental stress.

Question 15

Which of the following best describes the function of bacterial flagella?

Accepted Answer

They enable motility and movement.

Question 16

A researcher discovers a microorganism with a single, circular chromosome and small circular DNA molecules that replicate independently. What are these small DNA molecules called?

Accepted Answer

Plasmids

Question 17

Which nutritional mode is correctly matched with its energy and carbon sources?

Accepted Answer

Photoheterotroph: Light energy, organic carbon

Question 18

Which of the following is a major reason why Gram-negative bacteria are less sensitive to penicillin than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane that restricts antibiotic entry.

Question 19

Which of the following statements about the evolutionary relationship between Archaea and Eukaryotes is supported by recent phylogenetic studies?

Accepted Answer

Eukaryotes are a branch within the Archaea domain.

Question 20

A patient is infected with a bacterium that can only survive and reproduce inside host cells. Which of the following best describes this organism?

Accepted Answer

Obligate intracellular bacterium

Microbial Diversity: Prokaryotes, Eukaryotes, and Viruses

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