microbiology basic and clinical principles test bank -Nurselytic

Correct Answer: B

Rationale: The correct answer is B: non-spore forming encapsulated gram-negative bacterium. Francisella tularensis is a non-spore forming bacterium, which rules out choices A and D. It is encapsulated, which eliminates choice C. The encapsulation of the bacterium helps it evade the host immune system, leading to its pathogenicity. This encapsulated bacterium is responsible for causing the zoonotic disease tularemia in humans.

Correct Answer: A

Rationale: The correct answer is A: Clostridium tetani. This bacterium is known for causing tetanus due to its ability to produce tetanospasmin, a neurotoxin that leads to the characteristic muscle stiffness and spasms seen in tetanus. Clostridium perfringens (
Choice
B) is associated with gas gangrene, Streptococcus pyogenes (
Choice
C) causes streptococcal infections, and Escherichia coli (
Choice
D) is known for causing various gastrointestinal infections.
Therefore,

Choices B, C, and D are incorrect as they are not the causative agents of tetanus.

Correct Answer: D

Rationale: The correct answer is D (All of the above) because all three bacteria listed produce exotoxins that cause severe gastrointestinal illness. Clostridium botulinum produces botulinum toxin causing botulism. Vibrio cholerae produces cholera toxin leading to cholera. Escherichia coli can produce various exotoxins causing different types of severe gastrointestinal illnesses like E. coli O157:H7 causing bloody diarrhea.
Therefore, all choices A, B, and C are correct in this case as they all produce exotoxins causing severe gastrointestinal illness.

Correct Answer: B

Rationale: The correct answer is B: protein filaments made of flagellin. Bacterial flagella are composed of flagellin proteins arranged in helical filaments. This structure allows for movement and propulsion of bacteria.

A: 9+2 microtubule arrangement is incorrect because this structure is typically found in eukaryotic flagella, not bacterial flagella.
C: Lipid bilayer is incorrect as it is a structural component of cell membranes, not bacterial flagella.
D: Peptidoglycan layer is incorrect as it is a component of bacterial cell walls, not flagella.

Correct Answer: B

Rationale: The correct answer is B: Clostridium botulinum. This bacterium belongs to the Clostridium genus, known for its ability to produce endospores. Endospores are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (
A), Escherichia coli (
C), and Neisseria gonorrhoeae (
D) do not produce endospores. Staphylococcus aureus is a gram-positive bacterium known for causing various infections, but it does not form endospores. Escherichia coli is a gram-negative bacterium commonly found in the intestines of humans and animals, but it does not produce endospores. Neisseria gonorrhoeae is a gram-negative bacterium that causes the sexually transmitted infection gonorrhea, but it also does not form endospores.