microbiology chapter 13 test bank

Correct Answer: D

Rationale: The correct answer is D because viruses are sensitive to interferon, a natural defense mechanism of the body against viral infections. Interferon helps to inhibit viral replication. A: Viruses are cell-free infectious particles, not living systems. B: Viruses are obligate intracellular parasites as they require host cells to replicate. C: Viruses can have either DNA or RNA as genetic material, which is a characteristic feature.

Correct Answer: B

Rationale: The correct answer is B: Contains single-stranded RNA with negative polarity. Measles virus is an enveloped virus with a single-stranded RNA genome that is negative-sense. This means it must first be transcribed into positive-sense RNA before it can be translated. Choice A is incorrect as the measles virus does have an outer envelope. Choice C is incorrect as measles virus belongs to the family Paramyxoviridae, not Togaviridae. Choice D is incorrect as measles virus can be grown on cell cultures, specifically on Vero cells.

Correct Answer: D

Rationale: The correct answer is D: Chocolate agar. Neisseria meningitidis is a fastidious organism that requires enriched media for growth. Chocolate agar contains heat-treated blood that provides essential nutrients for the growth of N. meningitidis. The other choices, A: Levine agar, B: Lowenstein-Jensen agar, and C: TCBS agar, do not provide the specific nutrients required for the growth of N. meningitidis. Therefore, only choice D, Chocolate agar, supports the growth of N. meningitidis due to its enriched composition.

Correct Answer: A

Rationale: The correct answer is A: epidermis. Langerhans cells are a type of immune cell found in the epidermis, the outermost layer of the skin. They play a crucial role in the defense against microbes by capturing and presenting antigens to activate the immune system. The dermis (B), hypodermis (C), and subcutaneous layer (D) are located deeper in the skin and do not contain Langerhans cells. Therefore, the epidermis is the correct location for these immune cells to carry out their defensive functions.

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.