microbiology test bank

Correct Answer: A

Rationale: The correct answer is A: Bacteria. Urinary tract infections (UTIs) are primarily caused by the invasion of bacteria into the urinary tract. Bacteria, especially Escherichia coli (E. coli), are the most common culprits. They enter the urinary tract through the urethra and can multiply in the bladder, leading to infection. Viruses (choice B) and fungi (choice C) are not typical causes of UTIs. "None of the above" (choice D) is incorrect as bacteria are indeed the main cause of UTIs.

Correct Answer: D

Rationale: The correct answer is D, Klebsiella pneumoniae. Klebsiella pneumoniae is a fermentative gram-negative rod, which means it can ferment sugars. In contrast, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia are non-fermentative gram-negative rods. These organisms do not ferment sugars for energy production. Therefore, Klebsiella pneumoniae is the only fermentative organism among the choices, making it the correct answer.

Correct Answer: D

Rationale: The correct answer is D: Oral candidiasis. Soor is a term used to describe oral candidiasis, a fungal infection caused by Candida species. This infection presents as white patches on the tongue, inner cheeks, and roof of the mouth. The other choices (A, B, C) refer to different types of fungal infections affecting various parts of the body, not specifically the oral cavity. Therefore, based on the description of soor and its characteristics, the correct answer is D.

Correct Answer: C

Rationale: The correct answer is C because hemagglutinin of influenza viruses serves as an attachment molecule to the receptor of the target cell, facilitating viral entry. This is crucial for the virus to infect host cells. Choice A is incorrect because hemagglutinin is not part of the viral capsid but rather a surface protein. Choice B is incorrect as hemagglutinin is not directly involved in viral replication, but in host cell attachment. Choice D is incorrect as hemagglutinin is highly antigenic, triggering the host's immune response.

Correct Answer: A

Rationale: The correct answer is A: T-lymphocytes. Cell-mediated immunity involves the activation of T-lymphocytes, which play a crucial role in recognizing and killing infected cells. T-lymphocytes include cytotoxic T cells, helper T cells, and regulatory T cells, all of which are involved in different aspects of cell-mediated immunity. Monocytes (choice B) are a type of white blood cell involved in phagocytosis but are not the main mediators of cell-mediated immunity. B-lymphocytes (choice C) are involved in humoral immunity, producing antibodies, not cell-mediated immunity. Choice D (A+B+C) is incorrect because cell-mediated immunity is mainly mediated by T-lymphocytes.