mastering microbiology test bank

Correct Answer: B

Rationale: The Gram stain differentiates bacteria based on cell wall structure. It classifies bacteria into Gram-positive (purple) and Gram-negative (pink) based on the presence of peptidoglycan in the cell wall. This method helps in identifying the bacterial species and determining appropriate treatment. Option A (Cell shape) is incorrect because the Gram stain focuses on cell wall composition, not cell shape. Option C (Flagella composition) is incorrect as the Gram stain does not assess flagella. Option D (Nutrient requirements) is incorrect as it does not relate to the purpose of the Gram stain.

Correct Answer: B

Rationale: The correct answer is B: Rhodophyta. Rhodophyta is the phylum of red algae, which are known to contain agar in their cell walls. Agar is a gelatinous substance derived from these algae. Chrysophyta (A), Chlorophyta (C), and Phaeophyta (D) do not typically contain agar in their cell walls. Chrysophyta includes diatoms, Chlorophyta includes green algae, and Phaeophyta includes brown algae, none of which are known for agar production. Therefore, Rhodophyta is the correct choice based on the presence of agar in their cell walls.

Correct Answer: C

Rationale: The Baltimore classification system categorizes viruses based on their genome type and replication strategy. It divides viruses into seven groups: Group I (dsDNA), Group II (ssDNA), Group III (dsRNA), Group IV (ssRNA(+)), Group V (ssRNA(-)), Group VI (ssRNA-RT), and Group VII (dsDNA-RT). Each group represents a distinct viral genome and replication method. Therefore, the correct answer is C. The other choices are incorrect because the Baltimore classification system specifically identifies viruses into seven groups, not four, five, or nine.

Correct Answer: B

Rationale: The correct answer is B: Peptic ulcer. Peptic ulcers are commonly caused by Helicobacter pylori bacteria, which can be transmitted through the fecal-oral route. This means that the bacteria from infected feces can be ingested through contaminated food or water, leading to the development of peptic ulcers in the gastrointestinal tract. Incorrect choices: A: Ehrlichiosis - Ehrlichiosis is a tick-borne disease transmitted through the bite of an infected tick, not through the fecal-oral route. C: Lyme disease - Lyme disease is also transmitted through the bite of an infected tick, specifically the black-legged tick. D: Tularemia - Tularemia is a bacterial disease typically transmitted through insect bites, handling of infected animals, or ingestion of contaminated water, not through the fecal-oral route.

Correct Answer: A

Rationale: Rationale for Correct Answer (A: Fluconazole): Fluconazole is an antifungal medication used to treat yeast infections caused by Candida albicans. It targets the fungal cell membrane, disrupting its structure and function. This makes it an effective treatment for oral thrush, which is caused by Candida overgrowth in the oral mucosa. The continuous use of antibiotics can disrupt the normal balance of microorganisms in the body, leading to fungal overgrowth. Fluconazole specifically targets the yeast fungi without affecting bacteria, making it the appropriate choice for this complication. Summary of Incorrect Choices: B: Biseptol - Biseptol is an antibiotic that targets bacteria, not fungi like Candida albicans. C: Tetracycline - Tetracycline is also an antibiotic that targets bacteria, not fungi. D: Furazolidone - Furazolidone is an antibiotic primarily used for treating bacterial infections, not fungal infections like oral thrush caused by Candida