microbiology test bank

Correct Answer: B

Rationale: The correct answer is B: Motility. The bacterial flagellum is a whip-like appendage that helps bacteria move by rotating like a propeller. This motility allows bacteria to navigate their environment, find nutrients, and avoid harmful conditions. Choices A, C, and D are incorrect because the bacterial flagellum is not involved in protein synthesis, DNA replication, or spore formation. Protein synthesis occurs in ribosomes, DNA replication takes place in the nucleus or nucleoid, and spore formation is a specialized process involving the production of spores for survival in harsh conditions.

Correct Answer: A

Rationale: The correct answer is A: Bacterial vaginosis (gardnerellosis). The presence of clue cells on the Gram-stained smears is characteristic of bacterial vaginosis. Clue cells are vaginal epithelial cells covered with bacteria, specifically Gardnerella vaginalis, which is the causative agent of bacterial vaginosis. The symptoms described by the patient - itching, burning, watery discharge with a fish-like smell - are classic signs of bacterial vaginosis. The absence of alterations in the cervix, uterus, and appendages rules out other sexually transmitted infections like chlamydiosis, gonorrhea, and trichomoniasis. Therefore, the most likely pathology in this case is bacterial vaginosis.

Correct Answer: D

Rationale: The correct answer is D: To determine the children that need to receive BCG vaccination. The Mantoux test is used to identify individuals who have been exposed to Tuberculosis (TB) and need BCG vaccination for protection. Parotitis (choice A) is a viral infection unrelated to TB. Allergization rate toward rickettsia (choice B) and immune stress toward diphtheria (choice C) are not related to the Mantoux test or BCG vaccination. Therefore, choice D is the correct answer as it aligns with the purpose of the Mantoux test.

Correct Answer: A

Rationale: Step-by-step rationale for choice A: 1. Viruses contain genetic material in the form of nucleic acids (DNA or RNA). 2. Proteins are essential for the structure and function of viral particles. 3. Nucleic acids (genetic material) and proteins are the two main components of viruses. 4. Therefore, choice A (nucleic acid and proteins) is correct. Summary: - Choice B (nucleic acids and lipids) is incorrect as lipids are not a main structural component of viruses. - Choice C (lipids and proteins) is incorrect as nucleic acids are essential components of viruses. - Choice D (proteins and glycoproteins) is incorrect as glycoproteins are a type of protein and not a separate component in viruses.

Correct Answer: A

Rationale: The correct choice is A: Binding to IgE fixed to mast cells. The Besredka desensitization method involves injecting small, gradually increasing doses of the allergen to induce tolerance and prevent anaphylactic shock. This process works by binding the allergen to IgE antibodies fixed to mast cells, which prevents the release of histamine and other inflammatory mediators that trigger allergic reactions. This desensitization process helps the immune system become less reactive to the allergen over time. Incorrect choices: B: Inhibited synthesis of mast cells mediators - This choice does not reflect the mechanism of the Besredka desensitization method, which involves binding to IgE on mast cells. C: Stimulation of the immunological antigen tolerance - While this may sound plausible, the Besredka method specifically targets the IgE-mast cell interaction. D: Stimulation of antigen-specific IgG synthesis - While IgG antibodies may play a role in desensitization, the