foundations in microbiology test bank

Correct Answer: A

Rationale: The correct answer is A: They are enveloped viruses. Rhabdoviridae family consists of enveloped viruses, which means they have a lipid envelope surrounding their protein coat. This envelope helps the virus in infecting host cells and evading the immune system. The other choices are incorrect because B: They cause plague is not true as Rhabdoviridae family typically causes diseases like rabies in mammals. C: They have spherical shape is incorrect as rhabdoviruses have a bullet-shaped structure. D: They infect only humans is also incorrect as Rhabdoviridae viruses can infect a wide range of hosts beyond just humans.

Correct Answer: D

Rationale: The correct answer is D: Sporozoites. Sporozoites are the infective stage of Plasmodium for the female Anopheles mosquito. Here's the rationale: After being transmitted to a human host through a mosquito bite, the sporozoites travel to the liver where they mature and reproduce asexually as merozoites (not the infective stage for mosquitoes). The merozoites then infect red blood cells, leading to symptoms like fever, headache, and shivering. During the blood stage, some merozoites develop into male and female gametocytes, which are not infective to mosquitoes. When a mosquito bites an infected person, it ingests gametocytes, which then develop into male and female gametes and fuse to form ookinetes. Ookinetes develop into oocysts in the mosquito's gut, releasing sporozoites that migrate to the salivary glands, ready to infect a new human host when the mosquito bites

Correct Answer: C

Rationale: Step-by-step rationale: 1. Aspergillus flavus is a fungus known to produce aflatoxin. 2. Aflatoxin is a potent carcinogen found in contaminated food. 3. Candida albicans is a yeast species not associated with aflatoxin production. 4. Claviceps purpurea is a fungus that produces ergot alkaloids, not aflatoxin. 5. Staphylococcus aureus is a bacterium known for causing food poisoning, not aflatoxin production. Summary: Aspergillus flavus is the correct answer as it is the organism known to produce aflatoxin, a carcinogenic substance. Other choices are incorrect as they are not associated with aflatoxin production.

Correct Answer: C

Rationale: The correct answer is C: IFA - Immunofluorescence assay. Toxoplasmosis and chronic gonorrhea can be detected using serological tests like IFA. IFA detects specific antibodies in the patient's serum by using fluorescently labeled antibodies. This method is highly sensitive and specific for detecting both acute and latent infections. Explanation of Incorrect Choices: A: RIHA - Reverse indirect hemagglutination assay - This test is not commonly used for detecting toxoplasmosis or chronic gonorrhea. B: RDHA - Reverse direct hemagglutination assay - This test is not typically used for these specific infections. D: Immunoblot analysis - While Immunoblot analysis is a useful confirmatory test for certain infections, it is not the primary method for detecting toxoplasmosis or chronic gonorrhea.

Correct Answer: A

Rationale: The correct answer is A: Treponema. The characteristics described match Treponema pallidum, the causative agent of syphilis. Treponema has long, spiral shape with 8-12 regular coils. Leptospira (B) is a spirochete but has fewer coils and causes leptospirosis. Borrelia (C) is another spirochete but typically has irregular coils and causes Lyme disease. Vibrios (D) are curved rods and not spirochetes.