microbiology test bank

Correct Answer: C

Rationale: Step 1: The nucleocapsid is the structure containing the viral genome and the protein capsid. Step 2: The genome carries the genetic material of the virus. Step 3: The capsid is the protein coat that encloses and protects the viral genome. Step 4: Therefore, the correct answer is C: Genome and capsid. Summary: A: Capsid and spikes - Incorrect, spikes are not part of the nucleocapsid. B: Genome and envelop - Incorrect, the envelop is not part of the nucleocapsid. D: Capsid and envelope - Incorrect, the envelope is not part of the nucleocapsid.

Correct Answer: A

Rationale: The correct answer is A: Treponema pallidum. This is because Treponema pallidum is a thin spiral bacteria with 12-14 coils and pointed ends, which matches the description given in the question. Treponema pallidum is the causative agent of syphilis. Choices B, C, and D are incorrect: B: Leptospira - Leptospira is a spiral-shaped bacteria, but it does not have the specific characteristics mentioned in the question. C: Borrelia - Borrelia is another spiral-shaped bacteria, but it does not match the specific features described in the question. D: Spirochaeta - Spirochaeta is a genus of spiral-shaped bacteria, but it does not fit the description of having 12-14 coils and pointed ends as mentioned in the question.

Correct Answer: A

Rationale: The correct answer is A: Candida fungi. Candida fungi are known to cause oral thrush, characterized by whitish spots on the oral mucosa. The presence of gram-positive oval budding cells in the smear preparations is indicative of Candida species. Staphylococci (choice B) are gram-positive cocci, not oval budding cells. Sarcinae (choice C) are gram-positive bacteria that form cuboidal packets, not oval budding cells. Actinomycetes (choice D) are filamentous gram-positive bacteria, not oval budding cells like Candida fungi.

Correct Answer: B

Rationale: The main function of bacterial pili is to facilitate conjugation and adhesion. Pili are hair-like appendages on bacteria that help in cell-to-cell interactions. They play a crucial role in bacterial conjugation by allowing the transfer of genetic material between cells. Additionally, pili help bacteria adhere to surfaces or host cells, aiding in colonization and biofilm formation. Choices A and D are incorrect because protein synthesis and toxin secretion are not the primary functions of pili. Choice C is incorrect as bacterial motility is mainly mediated by flagella, not pili.

Correct Answer: B

Rationale: The correct answer is B: Clostridium tetani. Clostridium tetani produces tetanospasmin, a neurotoxin causing tetanus. It enters the body through wounds and affects the nervous system. A: Clostridium botulinum produces botulinum toxin causing botulism, not tetanus. C: Streptococcus pneumoniae causes pneumonia, not tetanus. D: Mycobacterium tuberculosis causes tuberculosis, not tetanus.