What condition is associated with C1q deficiency?

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: 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.

Correct Answer: B

Rationale: The correct answer is B because Toll-like receptors (TLRs) recognize common molecular patterns shared by groups of microbes, allowing for rapid detection of a wide range of pathogens. This recognition triggers immune responses without the need for prior exposure to the specific pathogen. The other choices are incorrect because: A: TLRs are not highly specific to individual pathogens but rather recognize common patterns. C: TLRs do not directly activate B cell antibody production; they initiate immune responses by activating various immune cells. D: TLRs do not require antigen presentation to function; they directly recognize microbial patterns.

Correct Answer: B

Rationale: The three main principles of adaptive immunity are Recognize, Respond, Remember. 1. Recognize: Immune system identifies specific pathogens through antigen recognition. 2. Respond: Immune response is triggered to eliminate the pathogen. 3. Remember: Immune system forms memory cells for faster and stronger response upon re-exposure. Other options are incorrect: A: Respond, Replace, Repair - Incorrect as it does not reflect the key processes of adaptive immunity. C: Resist, Retain, Recruit - Incorrect as these terms do not accurately describe the adaptive immune response. D: React, Replicate, Restore - Incorrect as it does not encompass the essential principles of adaptive immunity.

Correct Answer: B

Rationale: The correct answer is B: Fab region. The Fab region of an antibody contains the antigen-binding site, where specific interactions with antigens occur. This region is formed by the variable regions of both the heavy and light chains. The Fc fragment (choice A) is responsible for effector functions, not antigen specificity. The heavy chain constant region (choice C) and light chain constant region (choice D) are not involved in antigen binding, but rather provide structural support and determine the antibody class. Therefore, the Fab region is crucial for antigen specificity due to its variable regions that directly interact with antigens.