microbiology chapter 10 test bank

Correct Answer: B

Rationale: The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic environments. In aerobic conditions, they use oxygen for energy production, while in anaerobic conditions, they can switch to fermentation or anaerobic respiration. A: Obligate aerobes require oxygen to survive and cannot survive in anaerobic environments. C: Obligate anaerobes cannot survive in the presence of oxygen and only thrive in anaerobic conditions. D: Microaerophiles require low levels of oxygen to survive and cannot thrive in fully aerobic or anaerobic conditions.

Correct Answer: C

Rationale: The correct answer is C: Granuloma formation. In response to tuberculosis antigen (tuberculin), the immune system forms a granuloma at the injection site as a defense mechanism. Granulomas are organized collections of immune cells that wall off the antigen and prevent its spread. This process involves macrophages, T cells, and fibroblasts. Choice A (Cells cytotoxity) is incorrect because tuberculin test does not involve direct cell cytotoxicity. Choice B (Reagin type cytotoxity) is incorrect as reagin type hypersensitivity is associated with allergic reactions, not granuloma formation. Choice D (Immunocomplex cytotoxity) is also incorrect as immunocomplex cytotoxicity refers to tissue damage caused by immune complexes, not granuloma formation.

Correct Answer: A

Rationale: Step 1: Ziehl-Neelsen staining is a type of acid-fast staining used to detect acid-resistant bacteria like Mycobacterium species. Step 2: Acid-resistant bacteria have a high lipid content in their cell walls, making them resist decolorization with acid-alcohol. Step 3: Mycobacterium species, such as M. tuberculosis and M. leprae, are examples of acid-resistant bacteria. Step 4: Spores are not typically stained using Ziehl-Neelsen staining, making choice B incorrect. Step 5: Metachromatic bodies are stained using specific techniques like Albert's stain, not Ziehl-Neelsen staining, making choice C incorrect. Summary: Ziehl-Neelsen staining is specifically used for acid-resistant bacteria detection, making choice A the correct answer. Choices B and C are incorrect as they do not align with the purpose of Ziehl-Neelsen staining. Choice D is incorrect as Ziehl

Correct Answer: A

Rationale: Rationale: 1. Gram-positive cocci in clusters point to Staphylococcus or Micrococcus. 2. Catalase-positive eliminates Streptococcus. 3. Coagulase-positive distinguishes Staphylococcus aureus. 4. Thus, the causative agent is Staphylococcus aureus. Summary: - B: Streptococcus pyogenes is catalase-negative. - C: Enterococcus faecalis is catalase-negative. - D: Micrococcus luteus is catalase-positive but coagulase-negative.

Correct Answer: B

Rationale: The correct answer is B: Leptospirosis. Spiral-shaped bacteria with loose coils and pointed ends are characteristic of Leptospira interrogans, the causative agent of Leptospirosis. This bacterium is typically found in contaminated water or soil and can infect humans through contact with infected animals or water. Syphilis (Choice A) is caused by the spirochete Treponema pallidum, which has a more tightly coiled shape and does not typically appear loose or pointed. Relapsing fever (Choice C) is caused by Borrelia species, which are also spirochetes but do not have the loose coils and pointed ends described. Lyme disease (Choice D) is caused by Borrelia burgdorferi, which, like Relapsing fever, does not match the morphology described.