openstax microbiology test bank

Correct Answer: B

Rationale: The correct answer is B because collecting specimens from the surface of a wound does not provide adequate samples for anaerobic agent detection. Anaerobic agents thrive in deep tissue environments with low oxygen levels, making surface specimens unreliable. Tissue samples and aspirations (choice A) are superior for diagnosing skin infections. Excessive production of toxins, not skin rash (choice C), causes symptoms in some infections. While healthy skin provides some protection, it is not completely impenetrable to microorganisms (choice D).

Correct Answer: A

Rationale: The correct answer is A: Helicobacter pylori. Rationale: 1. Gram-negative spiral-shaped microorganisms match the morphology of Helicobacter pylori. 2. Positive urease activity is a characteristic feature of Helicjsonacter pylori. 3. Helicobacter pylori is specifically associated with gastric ulcers and is a common pathogen in the gastrointestinal tract. Summary: Choice B, Campilobacter jejuni, is a gram-negative curved bacterium but is not typically associated with gastric ulcers or urease activity. Choice C, Treponema pallidum, is a spirochete bacterium causing syphilis, which is not related to gastric ulcers. Choice D, Spirilla minor, is a generic term for spiral-shaped bacteria and is not a specific pathogen associated with gastric ulcers or urease activity.

Correct Answer: A

Rationale: The correct answer is A: Bacillus anthracis. This bacterium is known to form highly resistant spores that can survive for long periods in soil. Bacillus anthracis causes anthrax, a dangerous disease that can be transmitted to humans and animals. The other choices, Francisella tularensis, Brucella abortus, and Yersinia pestis, do not form spores as resistant as Bacillus anthracis. Therefore, only Bacillus anthracis is likely to have survived in the soil of the old burial ground for animal refuse for over 50 years.

Correct Answer: B

Rationale: The correct answer is B: Ethambutol. Ethambutol is known to cause optic neuritis, affecting the visual nerve. It is a well-documented side effect of this drug. Isoniazid (Choice A) is associated with peripheral neuropathy, not optic neuritis. Kanamycin (Choice C) is known for its side effects on the inner ear, causing hearing loss. Rifampicin (Choice D) is not typically associated with optic neuritis but can cause other adverse effects like hepatitis. By process of elimination and knowledge of drug side effects, Ethambutol is the most likely culprit.

Correct Answer: C

Rationale: The correct answer is C: Thermophiles. Thermophiles are bacteria that thrive in high temperatures typically above 45�C. They have specialized enzymes and cellular structures that allow them to survive and even thrive in extreme heat. Psychrophiles (A) are adapted to cold temperatures, mesophiles (B) thrive at moderate temperatures, and halophiles (D) prefer high salt concentrations, making them unsuitable for extreme heat survival. Therefore, Thermophiles are the only bacteria among the choices that are known for their ability to survive in extreme heat.