What are haematopoietic stem cells responsible for?

Correct Answer: B

Rationale: Haematopoietic stem cells are responsible for producing immune cells. These stem cells differentiate into various types of blood cells, including white blood cells that play a crucial role in the immune system. They do not differentiate into lymph nodes (A), generate cytokines (C), or suppress pathogens directly (D). The correct answer (B) aligns with the primary function of haematopoietic stem cells in the production of immune cells.

Correct Answer: B

Rationale: The correct answer is B because innate immunity instructs and activates adaptive immunity. Innate immunity serves as the first line of defense against pathogens, recognizing and initiating a response to pathogens. It then communicates with adaptive immunity, providing signals and antigens to activate and guide the adaptive immune response. This collaboration is crucial for the effective elimination of pathogens. Choices A, C, and D are incorrect because innate immunity does not suppress, replace, or function independently of adaptive immunity; rather, they work together in a coordinated manner to provide a comprehensive immune response.

Correct Answer: B

Rationale: Rationale: C1q is a component of the classical complement pathway, crucial for immune complex clearance. Its deficiency is associated with SLE due to impaired immune complex removal, leading to autoantibody deposition and inflammation. Cancer, HIV/AIDS, and COPD are not directly linked to C1q deficiency.

Correct Answer: C

Rationale: The correct answer is C: Recruitment and activation of immune cells. C5a is a potent chemoattractant that attracts immune cells to the site of infection or inflammation. It also activates these immune cells, leading to enhanced immune responses. Option A (Opsonization) and B (Cell lysis) are not the main functions of C5a. Option D (Inhibition of inflammation) is incorrect because C5a actually promotes inflammation by recruiting and activating immune cells.

Correct Answer: B

Rationale: The correct answer is B because cytokines act as signaling molecules to coordinate immune responses in innate immunity. They help regulate inflammation, activate immune cells, and promote clearance of pathogens. Option A is incorrect because cytokines do not directly kill pathogens. Option C is incorrect as cytokines play a crucial role in both innate and adaptive immunity. Option D is incorrect because cytokines do not inhibit phagocytosis; instead, they enhance this process to help eliminate pathogens.