Which immune system function is most relevant to cancer?

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: 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.

Correct Answer: C

Rationale: The correct answer is C. NK cells kill target cells by releasing perforin and granzyme. Perforin creates pores in the target cell's membrane, allowing granzyme to enter and induce apoptosis. Antibodies (choice A) are produced by B cells, not NK cells. Cytokines (choice B) regulate immune responses but do not directly kill cells. Phagocytosis (choice D) involves engulfing and digesting pathogens, which is not how NK cells kill target cells.

Correct Answer: C

Rationale: The correct answer is C: Lymphoid lineage. NK cells are a type of lymphocyte that is part of the innate immune system. They are derived from common lymphoid progenitors in the bone marrow. NK cells play a crucial role in recognizing and killing infected or abnormal cells. Myeloid lineage (A) gives rise to cells like macrophages and granulocytes, not NK cells. Erythroid lineage (B) produces red blood cells, and granulocyte lineage (D) gives rise to neutrophils, basophils, and eosinophils, not NK cells. Therefore, the correct choice is C as NK cells originate from the lymphoid lineage.

Correct Answer: A

Rationale: The correct answer is A: Lysosomes. Lysosomes contain enzymes that break down engulfed pathogens during phagocytosis. First, the pathogen is engulfed by the cell membrane forming a phagosome. Next, the phagosome fuses with a lysosome forming a phagolysosome where digestion occurs. Golgi apparatus (B) is involved in protein processing and packaging. Endoplasmic reticulum (C) is responsible for protein synthesis and lipid metabolism. Mitochondria (D) produce energy in the form of ATP.