microbiology chapter 13 test bank

Correct Answer: C

Rationale: The correct answer is C: Method of Moller. This method uses malachite green to stain bacterial spores due to their resistance to decolorization. The other choices, A, B, and D, are incorrect because Romanovski-Gymsa is used for staining blood smears, Ziehl-Nielsen is used for acid-fast bacteria, and Neisser is used for staining Neisseria species, not bacterial spores.

Correct Answer: B

Rationale: The correct answer is B: Transformation. Frederick Griffith discovered bacterial transformation, where genetic material can be transferred between bacteria. He observed this phenomenon while studying pneumonia-causing bacteria in 1928. Transformation is the process by which bacteria take up external DNA and incorporate it into their own genome. This discovery was crucial in understanding how genetic information can be transferred between organisms. Rationale for other choices: A: Translation - This term refers to the process of protein synthesis from mRNA, not relevant to Griffith's discovery. C: Transcription - This term refers to the process of synthesizing RNA from DNA, not related to Griffith's discovery. D: Conjugation - This term refers to the direct transfer of genetic material between bacterial cells through cell-to-cell contact, which is different from the phenomenon Griffith observed.

Correct Answer: C

Rationale: Rationale: 1. Vibrio cholerae produces cholera toxin causing severe diarrhea. 2. Clostridium tetani causes tetanus, not diarrhea. 3. Clostridium botulinum causes botulism, not diarrhea. 4. Shigella dysenteriae causes dysentery, not typical diarrhea. Summary: A: Incorrect, causes tetanus. B: Incorrect, causes botulism. C: Correct, produces cholera toxin causing severe diarrhea. D: Incorrect, causes dysentery.

Correct Answer: A

Rationale: The correct answer is A: Hyperresponsiveness reaction type IV. This type of reaction, also known as delayed-type hypersensitivity, is characterized by the activation of T lymphocytes and macrophages, leading to inflammation at the site of antigen exposure. In the case of the Mantoux test, the appearance of a papule 48 hours later indicates a delayed hypersensitivity reaction mediated by T cells. Choice B: Reaction of Arthus phenomenon type is incorrect as this type of reaction involves immune complexes forming in the blood vessels leading to tissue damage, which is not the mechanism seen in the Mantoux test reaction. Choice C: Reaction of serum sickness type is incorrect as this type of reaction involves the formation of immune complexes in the blood leading to systemic symptoms like fever, rash, and joint pain, which is not typically seen in the Mantoux test reaction. Choice D: Atopic reaction is incorrect as atopic reactions involve IgE antibodies and mast cell degranulation, which are not the mechanisms

Correct Answer: A

Rationale: The correct answer is A: Neisser staining method. Neisser staining method is used to stain diphtheria bacilli, which appear as blue rods with thickenings at the poles. The rationale is that Neisser staining specifically targets and highlights the characteristics of the diphtheria bacilli. Incorrect choices: B: Gram staining is not specific for diphtheria bacilli and does not show the characteristic blue rods with thickenings at the poles. C: Ziehl-Neelsen staining is used for acid-fast bacteria like Mycobacterium tuberculosis, not for diphtheria bacilli. D: Loeffler staining is used for diphtheria bacilli but does not produce blue rods with thickenings at the poles as seen in this case.