Question 1

Which of the following statements best explains why gram-negative bacteria are generally more resistant to antibiotics than gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane containing lipopolysaccharides that restricts antibiotic access.

Question 2

A patient is diagnosed with a bacterial infection caused by a species that survives in the human gut by producing methane. Which group does this bacterium most likely belong to?

Accepted Answer

Methanogens

Question 3

Which process allows a nonpathogenic bacterium to become pathogenic by acquiring DNA from its environment, and what is this process called?

Accepted Answer

The bacterium incorporates foreign DNA through transformation.

Question 4

Which of the following best describes the nutritional mode of a bacterium that uses light for energy and CO$$_2 as a $$carbon source?

Accepted Answer

Photoautotroph

Question 5

A researcher discovers a prokaryote living in a hot spring at 95$$^\circC. $$Which adaptation is most likely present in this organism?

Accepted Answer

Proteins and DNA stabilized for high temperatures

Question 6

Which of the following is a real-world example of exaptation in prokaryotes?

Accepted Answer

The evolution of bacterial flagella from proteins originally used in secretion systems

Question 7

A hospital patient develops a chronic infection on a catheter that is resistant to antibiotics. Which prokaryotic adaptation most likely contributes to this problem?

Accepted Answer

Formation of biofilms on the catheter surface

Question 8

Which of the following best explains why salt is effective as a food preservative?

Accepted Answer

Salt causes prokaryotic cells to undergo plasmolysis, slowing their reproduction.

Question 9

Which of the following statements about the CRISPR-Cas9 system is correct?

Accepted Answer

It is a bacterial defense mechanism that has been adapted for gene editing in research.

Question 10

A scientist is studying a bacterium that can survive with or without oxygen by switching between aerobic respiration and fermentation. What is the correct term for this metabolic strategy?

Accepted Answer

Facultative anaerobe

Question 11

Which of the following is a direct consequence of horizontal gene transfer among bacteria?

Accepted Answer

Rapid spread of antibiotic resistance genes across different species

Question 12

Which of the following best describes the role of nitrogen-fixing bacteria in the biosphere?

Accepted Answer

They convert atmospheric N$$_2$$ into ammonia (NH$$_3$$), making nitrogen available to plants.

Question 13

Which of the following is true regarding the structure and function of prokaryotic flagella?

Accepted Answer

They are composed of multiple proteins forming a motor, hook, and filament, and evolved through exaptation.

Question 14

A bacterial cell is found to contain an F plasmid. Which of the following statements is correct regarding its ability to transfer genetic material?

Accepted Answer

It can function as a DNA donor during conjugation.

Question 15

Which of the following is an example of mutualism involving prokaryotes in the human body?

Accepted Answer

Bacteroides thetaiotaomicron synthesizing vitamins in the human intestine

Question 16

Which of the following best explains why antibiotics that target peptidoglycan synthesis are generally safe for human use?

Accepted Answer

Human cells lack peptidoglycan, so antibiotics do not harm them.

Question 17

A soil bacterium is found to produce a polymer called PHA. What is a practical application of this bacterial product?

Accepted Answer

Production of biodegradable plastics

Question 18

Which of the following scenarios illustrates the process of transduction in bacteria?

Accepted Answer

A bacteriophage transfers DNA from one bacterial cell to another during infection.

Question 19

Which of the following is a distinguishing feature of archaeal cell walls compared to bacterial cell walls?

Accepted Answer

Archaeal cell walls lack peptidoglycan and may contain polysaccharides and proteins.

Question 20

A patient is infected with a bacterium that causes disease only when the bacteria die and their cell walls break down, releasing toxins. Which type of toxin is responsible?

Accepted Answer

Endotoxin

Prokaryotes: Structure, Function, Diversity, and Impact

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