What is the primary function of cytokines in the immune system?

Correct Answer: B

Rationale: The correct answer is B: To orchestrate and drive immune responses. Cytokines are signaling molecules that coordinate various aspects of the immune response, such as inflammation, cell proliferation, and differentiation. They regulate communication between immune cells to mount an effective defense against pathogens. A: To act as a physical barrier to pathogens - Incorrect. Physical barriers include skin and mucous membranes, not cytokines. C: To destroy red blood cells - Incorrect. Cytokines are not involved in destroying red blood cells. D: To generate antibodies - Incorrect. While cytokines can influence antibody production, their primary role is not in generating antibodies.

Correct Answer: A

Rationale: The correct answer is A: Bone marrow. Secondary lymphoid organs are where immune responses are initiated. Bone marrow is a primary lymphoid organ where immune cells mature, not where immune responses are initiated like in secondary lymphoid organs. The spleen, lymph nodes, and mucosal immune system are all secondary lymphoid organs where immune responses occur.

Correct Answer: B

Rationale: The correct answer is B: 1796. This is because the first vaccine for smallpox was developed by Edward Jenner in 1796. He used cowpox virus to create immunity against smallpox. Choices A, C, and D are incorrect because they do not align with historical records of the development of the smallpox vaccine. Choice A (1726) is too early, choices C (1882) and D (1895) are much later dates and do not correspond to the actual timeline of the smallpox vaccine's discovery.

Correct Answer: B

Rationale: The correct answer is B: Recognition, ingestion, and digestion. Firstly, recognition is essential for phagocytes to identify and bind to the target. Next, ingestion involves engulfing the target into a phagosome. Finally, digestion occurs within the phagolysosome, where enzymes break down the target. Choices A, C, and D are incorrect because they do not accurately represent the sequential key steps of phagocytosis.

Correct Answer: D

Rationale: The correct answer is D. Innate immunity does not involve producing antigen-specific antibodies. This is because innate immunity is the first line of defense against pathogens and does not have the ability to produce antibodies that target specific antigens. Instead, innate immunity works through mechanisms like phagocytosis and killing infected cells to eliminate pathogens. Choices A, B, and C are functions of innate immunity. A - Killing virally infected cells is a common function of innate immunity. B - Phagocytosis is the process by which immune cells engulf and destroy pathogens, a key function of innate immunity. C - Activating adaptive immunity is also a role of innate immunity, as it helps initiate the adaptive immune response for a more targeted defense.