Microbiology Test Bank

Correct Answer: A

Rationale: Step-by-step rationale: 1. Anopheles mosquitoes are the primary vectors for transmitting malaria. 2. They prefer stagnant water for breeding, common in tropical regions. 3. Culex mosquitoes primarily spread diseases like West Nile virus. 4. Aedes mosquitoes transmit diseases like Zika and dengue fever. 5. Mansonia mosquitoes are known for transmitting filarial diseases. Therefore, the correct answer is A (Anopheles), as they are specifically associated with spreading malaria.

Correct Answer: D

Rationale: The correct answer is D: Fifth disease. Rubella virus is associated with Fifth disease, also known as erythema infectiosum. It is caused by parvovirus B19, not rubella virus. Mumps (choice A) is caused by the mumps virus. Roseola (choice B) is caused by human herpesvirus 6 or 7. Rubeola (choice C) is the scientific name for measles, caused by the measles virus. Therefore, the correct answer is Fifth disease as it is the disease associated with rubella virus.

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: D

Rationale: The correct answer is D: Single stranded segmented (-) RNA. Orthomyxoviridae family includes influenza viruses, which have a genome composed of single-stranded segmented negative-sense RNA. This specific structure allows for efficient replication and transcription within host cells. Choice A is incorrect as orthomyxoviruses do not have a double-stranded DNA genome. Choice B is incorrect because orthomyxoviruses have a negative-sense RNA genome, not a positive-sense RNA genome. Choice C is incorrect as orthomyxoviruses do not have a double-stranded RNA genome.

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.