microbiology chapter 12 test bank

Correct Answer: A

Rationale: Step-by-step rationale: 1. Arenaviridae family includes viruses with a segmented genome. 2. Lassa virus has a segmented genome, placing it in the Arenaviridae family. 3. Crimean-Congo hemorrhagic fever virus belongs to the Nairoviridae family, not Arenaviridae. 4. Rabies virus belongs to the Rhabdoviridae family, not Arenaviridae. 5. Epstein-Barr virus belongs to the Herpesviridae family, not Arenaviridae. Summary: A: Lassa virus is correct because it has a segmented genome, characteristic of Arenaviridae. B, C, D: Crimean-Congo hemorrhagic fever virus, Rabies virus, and Epstein-Barr virus belong to different virus families, not Arenaviridae.

Correct Answer: D

Rationale: The correct answer is D: Intestinal trichomonad. This protozoan matches the description provided, with pyriform shape, twin nuclei, four pairs of flagella, supporting filaments, and a suctorial disc. Lamblia (A) lacks flagella and supporting filaments. Toxoplasma (B) is an intracellular parasite with different morphology. Leishmania (C) belongs to a different class with no flagella or supporting filaments. In summary, the unique combination of features described in the question points to an intestinal trichomonad, making it the correct answer.

Correct Answer: A

Rationale: Step 1: Small, curved Gram-negative bacilli with a monotrichous flagellum point towards a motile bacterium. Step 2: The absence of spores or capsules and preference for alkaline conditions further narrows down the possibilities. Step 3: Vibrio cholerae fits all criteria as it is a curved, motile, Gram-negative bacillus that thrives in alkaline environments. Summary: Escherichia coli is a facultative anaerobe, Salmonella and Shigella are non-flagellated, and all of them can form capsules or spores, unlike Vibrio cholerae.

Correct Answer: C

Rationale: The correct answer is C: Inhibits protein synthesis. Exotoxin of C. Diphtheriae acts by inhibiting protein synthesis in host cells. This disrupts cellular functions and leads to tissue damage. Choice A is incorrect because acetylcholine release is not affected. Choice B is incorrect as it does not involve neurotransmitters. Choice D is incorrect as the exotoxin does have a specific mechanism.

Correct Answer: A

Rationale: The correct answer is A: Borrelia burgdorferi. This bacterium is known for causing Lyme disease, which is transmitted through tick bites. Borrelia burgdorferi is specifically associated with Lyme disease due to its ability to infect and spread within the body, leading to a range of symptoms if left untreated. Summary of incorrect choices: B: Clostridium difficile - Known for causing gastrointestinal infections, not Lyme disease. C: Streptococcus pneumoniae - Commonly causes pneumonia and other respiratory infections, not Lyme disease. D: Mycobacterium tuberculosis - Causes tuberculosis, a respiratory disease, not Lyme disease.