TLRs contain a cytoplasmic TIR domain also found in the receptor of

Correct Answer: B

Rationale: Step-by-step rationale for Choice B (IL-1β) being correct: 1. The TIR domain is present in Toll-like receptors (TLRs) and IL-1 receptor. 2. TLRs recognize various microbial products, while IL-1 receptor binds IL-1 cytokines. 3. Both TLRs and IL-1 receptor signal through the TIR domain. 4. IL-1β is a cytokine that binds to IL-1 receptor, which contains a TIR domain. Summary of why the other choices are incorrect: A: Type I Interferons - Type I interferons signal through JAK-STAT pathway, not TIR domain. C: TNF-α - TNF receptor family signals through TNF receptor-associated death domain, not TIR domain. D: IL-8 - IL-8 binds to CXCR1 and CXCR2 receptors, which do not contain a TIR domain. In summary, Choice B

Correct Answer: B

Rationale: The correct answer is B: Phagocytosis. Elie Metchnikoff is credited with discovering phagocytosis, the process in which certain cells engulf and digest foreign particles or microorganisms. He observed this phenomenon in starfish larvae, leading to a groundbreaking understanding of how immune cells defend the body against pathogens. Choice A (Antitoxins) is incorrect because although Metchnikoff made contributions to immunology, his notable discovery was phagocytosis, not antitoxins. Choice C (Germ theory of disease) is incorrect as this theory was developed by Louis Pasteur and Robert Koch. Choice D (Smallpox eradication) is incorrect as this achievement is primarily attributed to the efforts of Edward Jenner and the World Health Organization.

Correct Answer: B

Rationale: Interferons are the correct answer as they are a cytokine group primarily associated with antiviral responses. They play a key role in the immune response against viral infections by inhibiting viral replication and spreading to other cells. Interleukins are more diverse and involved in various immune responses, not specifically antiviral. Tumor necrosis factors are more related to inflammation and cell death. Transforming growth factors are involved in cell growth and differentiation, not primarily antiviral responses. Therefore, B: Interferons is the most appropriate choice for cytokine group associated with antiviral responses.

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Innate immunity is the first line of defense and does not have memory. 2. Memory is a characteristic of adaptive immunity, not innate immunity. 3. Adaptive immunity improves responses over time through memory. 4. Innate immunity is always present, functional, non-specific, and responds immediately. Summary: A: Always present and functional - Correct, innate immunity is always ready. B: Has memory to improve responses over time - Incorrect, innate immunity lacks memory. C: Recognizes pathogens in a non-specific manner - Correct, innate immunity is non-specific. D: Can respond immediately - Correct, innate immunity acts rapidly.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.