Medical Microbiology Test Bank

Correct Answer: B

Rationale: The correct answer is B: Salmonellosis. The description of microorganisms resembling a tennis racket indicates the presence of Salmonella typhi, which causes salmonellosis. Salmonella bacteria can appear like tennis rackets under a microscope due to their flagella. Botulism (A) is caused by Clostridium botulinum, which does not resemble a tennis racket. Cholera (C) is caused by Vibrio cholerae, which appears as curved rods under the microscope. Dysentery (D) is usually caused by bacteria like Shigella or Entamoeba histolytica, which do not resemble tennis rackets.

Correct Answer: D

Rationale: The correct answer is D because all of the symptoms mentioned (short period of depression, nausea, restlessness) can be early signs of rabies. Rabies typically presents with a variety of non-specific symptoms in the early stages, including behavioral changes such as depression and restlessness, as well as gastrointestinal symptoms like nausea. Therefore, it is important to consider the combination of these symptoms collectively rather than individually when suspecting rabies. Choices A, B, and C alone may not definitively indicate rabies, but when seen together, they should raise suspicion and prompt further evaluation and testing for rabies.

Correct Answer: C

Rationale: To calculate the total magnification, we multiply the magnification of the ocular lens by the magnification of the objective lens. In this case, 10 (ocular) x 40 (objective) = 400. This is why choice C (400) is correct. Choices A, B, and D are incorrect because they do not represent the correct calculation of total magnification based on the given magnification powers of the ocular and objective lenses.

Correct Answer: C

Rationale: The correct answer is C: ensure survival under harsh conditions. Bacterial endospores are dormant, resistant structures that form under adverse conditions to protect the bacterial DNA and allow the bacterium to survive extreme environments. This function is crucial for the bacterium's long-term survival. Choice A is incorrect as endospores do not directly produce exotoxins. Choice B is incorrect as endospores do not store nutrients but rather protect the bacterium's genetic material. Choice D is incorrect as endospores do not enhance motility but rather enable survival during unfavorable conditions.

Correct Answer: A

Rationale: The correct answer is A: Icosahedral structures. Icosahedral symmetry is commonly found in viruses due to its efficient way of packing genetic material. The icosahedron has 20 equilateral triangular faces, making it ideal for viral capsids. The other choices, B: Hexahedral, C: Tetrahedral, and D: Dodecahedral structures, do not accurately describe the cubic type of symmetry seen in viruses. Hexahedral refers to a six-faced polyhedron, tetrahedral to a four-faced polyhedron, and dodecahedral to a twelve-faced polyhedron, none of which align with the structure commonly observed in viruses.