microbiology an introduction tortora test bank

Correct Answer: B

Rationale: The correct answer is B because Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are the most common causative agents of bacterial meningitis. Streptococcus pneumoniae is a leading cause in adults, Neisseria meningitidis is common in adolescents and young adults, and Haemophilus influenzae is more frequent in children. The other choices, Rubella virus (C) and Herpangina (D), are not bacterial agents known to cause meningitis.

Correct Answer: D

Rationale: The correct answer is D, Formation of CD4+ cells. In autoimmune reactions, CD4+ cells are actually involved in the immune response. Here's the rationale: 1. CD4+ cells are helper T cells that play a crucial role in activating other immune cells in autoimmune reactions. 2. Decreased functional activity of T-suppressors (Choice A) is typical in autoimmune reactions as it leads to unchecked immune responses. 3. Loss of tolerance for T-helpers and B-lymphocytes (Choice B) is common in autoimmune reactions, where the immune system mistakenly attacks self-cells. 4. Ag released by normally isolated tissues (Choice C) is a typical mechanism in autoimmune reactions where self-antigens trigger immune responses.

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: The correct answer is B because the complement fixation test is a serological test that detects the presence of specific antibodies or antigens in a patient's serum. It works by measuring the ability of antibodies to fix complement proteins. Choice A is incorrect because the complement fixation test typically involves several steps, not necessarily three. Choice C is incorrect as standardized complement proteins are commonly used in this test. Choice D is incorrect because sheep red blood cells are not essential for performing the complement fixation test.

Correct Answer: A

Rationale: The correct answer is A: virulence. Virulence refers to the degree or extent of disease-evoking power that a microorganism possesses. This term specifically describes the ability of a microorganism to cause disease in a host. It is a crucial factor in understanding the pathogenicity of different microorganisms. Choice B: strength is incorrect because it does not specifically relate to the disease-causing potential of a microorganism. Choice C: resistance refers to the ability of an organism to withstand the effects of a particular agent, such as a drug or environmental factor. Choice D: competence is not directly related to the disease-causing ability of a microorganism, but rather refers to the ability of an organism to perform a specific function effectively.