Which of the following microorganisms are always in a parasitic form of interaction with the individual?

Correct Answer: A

Rationale: The correct answer is A: viruses. Viruses are always in a parasitic form of interaction with the individual because they cannot survive or reproduce outside of a host cell. They rely on host cells to replicate and cause harm. Non-pathogenic bacteria (choice B) do not always cause harm and can coexist with the individual. Facultative pathogenic bacteria (choice C) can switch between being beneficial and harmful. Therefore, the correct answer is A as viruses always rely on a host for survival and reproduction.

Correct Answer: C

Rationale: The correct answer is C: flagella. Flagella are whip-like structures that move fluid, mucus, or cells over the surface of a cell. They are longer and fewer in number compared to cilia, which are shorter and more numerous. Fimbriae are small, bristle-like structures that help bacteria attach to surfaces but do not move fluid. Microvilli are tiny projections that increase the surface area for absorption but do not have a role in moving fluid or cells. Therefore, flagella is the correct answer as it specifically fits the function described in the question.

Correct Answer: B

Rationale: The correct answer is B: Availability of cell-mediated immunity to tuberculosis. A negative Mantoux test indicates the presence of an immune response to the TB bacteria, as the test measures the body's delayed hypersensitivity reaction to TB antigens. This means the child has been exposed to TB in the past or has been vaccinated, resulting in the development of cell-mediated immunity against TB. Incorrect choices: A: No cell-mediated immunity to tuberculosis - This is incorrect as a negative Mantoux test actually indicates the presence of cell-mediated immunity. C: No antibodies to the tuberculosis bacteria - Mantoux test measures cell-mediated immunity, not antibody response. D: No anti-toxic immunity to tuberculosis - Mantoux test does not assess anti-toxic immunity, it specifically measures cell-mediated immunity.

Correct Answer: C

Rationale: The correct answer is C: Intracellular parasitism. Genus Rickettsia representatives are known for their ability to live and replicate inside the host's cells, making them obligate intracellular parasites. This characteristic distinguishes them from other bacteria. A: Gram-positive cell wall is incorrect because Rickettsia have a gram-negative cell wall. B: High resistance to external environment factors is incorrect because Rickettsia are sensitive to environmental conditions and require specific host cells for survival. D: None of the above is incorrect because Rickettsia do exhibit the characteristic of intracellular parasitism.

Correct Answer: B

Rationale: The correct answer is B: Mycobacterium tuberculosis. This bacterium is responsible for causing tuberculosis. Mycobacterium tuberculosis specifically targets the lungs, leading to respiratory symptoms and can spread to other parts of the body. Streptococcus pneumoniae (A) is known for causing pneumonia, Neisseria meningitidis (C) causes meningitis, and Clostridium botulinum (D) causes botulism, not tuberculosis. Mycobacterium tuberculosis is the only bacterium among the choices that is associated with tuberculosis.

Correct Answer: B

Rationale: The correct answer is B: FALSE. Adenoviral infections are not restricted only to the upper respiratory tract; they can also affect the gastrointestinal tract, eyes, and other organs. Adenoviruses are known to cause a wide range of illnesses beyond just respiratory infections. Therefore, option B is correct. Option A is incorrect because it states that adenoviral infections are restricted to the upper respiratory tract, which is not true. Option C is incorrect because there is no circumstance where adenoviral infections are solely limited to the upper respiratory tract. Option D is also incorrect as the correct answer is B.

Correct Answer: B

Rationale: Rationale: 1. The grain-like sediment indicates a precipitation reaction. 2. Precipitins are antibodies that cause precipitation reactions. 3. In serological diagnostics, precipitation reactions are used to detect specific antibodies. 4. Therefore, the reaction revealed in this scenario is due to the presence of precipitins. Summary: A: Bacteriolysins - These antibodies cause bacterial lysis, not precipitation. C: Antitoxins - These antibodies neutralize toxins, not involved in precipitation reactions. D: Opsonins - These antibodies enhance phagocytosis, not related to precipitation reactions.

Correct Answer: A

Rationale: The correct answer is A because Fluconazole, Orungal, and Nizoral are antifungal medications commonly used for prevention of fungal infections. Fluconazole is a systemic antifungal agent, Orungal (Itraconazole) is used for various fungal infections, and Nizoral (Ketoconazole) is effective against a wide range of fungal infections. Choices B, C, and D do not contain antifungal medications and are unrelated to preventing fungal infections.

Correct Answer: A

Rationale: Step 1: A bacterial colony is a visible formation: Correct as colonies are visible to the naked eye. Step 2: Formed by clustering of cells: Correct as colonies are made up of numerous bacterial cells. Step 3: Belonging to different bacterial species: Correct as colonies can consist of one or multiple species. Summary: Choice A is correct as it accurately describes a bacterial colony. Choice B is incorrect as colonies can also form on solid nutrient mediums. Choice C is incorrect as choice A is correct. Choice D is incorrect as there is a correct option provided.