The human immunodeficiency virus (HIV)

Correct Answer: D

Rationale: Step 1: HIV is a retrovirus because it contains RNA as its genetic material and uses the enzyme reverse transcriptase to convert its RNA into DNA. Step 2: HIV is an RNA virus because its genetic material is RNA. Step 3: HIV is a lentivirus which is a subgroup of retroviruses known for causing slow-progressing diseases. Therefore, the correct answer is D as all statements A, B, and C are true based on the characteristics of HIV.

Correct Answer: C

Rationale: The correct answer is C because adaptive immunity involves T and B lymphocytes that provide specific immune responses tailored to particular pathogens. T and B lymphocytes are key players in adaptive immunity, recognizing and targeting specific antigens. Choice A is incorrect because macrophages are part of innate immunity. Choice B is incorrect because innate immunity is nonspecific and immediate, while adaptive immunity is specific and takes time to develop. Choice D is incorrect because physical barriers are a characteristic of innate immunity, not adaptive immunity.

Correct Answer: C

Rationale: The correct answer is C: Identifying and eliminating abnormal cells. This function is most relevant to cancer because the immune system's ability to recognize and destroy abnormal cells is crucial in preventing the development and spread of cancer. The immune system constantly surveys the body for cells that have mutated or become cancerous, and when identified, it initiates an immune response to eliminate them. This process is essential for maintaining the body's health and preventing cancerous cells from proliferating. Choice A (Suppressing cytokine release) is incorrect because cytokines play a role in regulating the immune response, which can be important in cancer immunity. Choice B (Promoting adaptive immunity only) is incorrect as both innate and adaptive immune responses are involved in combating cancer. Choice D (Limiting the effectiveness of phagocytes) is incorrect as phagocytes are important in recognizing and destroying cancer cells.

Correct Answer: A

Rationale: Step 1: Selective genetic pressure refers to the process where specific genetic traits are favored due to environmental factors. Step 2: Rroma populations and their genetic response to Yersinia pestis demonstrate selective genetic pressure as they have developed genetic adaptations to resist the plague bacterium. Step 3: This adaptation is a result of prolonged exposure to the pathogen, leading to the survival and reproduction of individuals with genetic variations that confer resistance. Step 4: Other choices are incorrect because mutation rates in viruses like the flu (B) do not necessarily involve genetic pressure, increased pathogen diversity in unvaccinated populations (C) is a consequence of lack of immunity, and non-specific activation of innate immunity (D) is not a selective process based on genetic traits.

Correct Answer: B

Rationale: The correct answer is B: Jules Hoffman. He is credited with identifying Toll-like receptors (TLRs) in innate immunity. Hoffman's research provided crucial insights into how the immune system recognizes pathogens and triggers immune responses. Paul Ehrlich is known for his work on antibodies, Edward Jenner for developing the smallpox vaccine, and Louis Pasteur for his contributions to germ theory and vaccination. However, none of them are specifically associated with the discovery of Toll-like receptors in innate immunity.