Which of the following is NOT a characteristic of innate immunity?

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: The correct answer is B (C3a, C4a, and C5a) because these complement components are known as anaphylatoxins that mediate inflammation by inducing vasodilation, increasing vascular permeability, and recruiting immune cells. C3b (choice A) is involved in opsonization, not inflammation. C5b (choice C) is part of the membrane attack complex for cell lysis. C1q (choice D) initiates the classical complement pathway, but it does not directly mediate inflammation.

Correct Answer: C

Rationale: Step 1: Innate immunity is the body's first line of defense against pathogens. Step 2: Physical defenses include barriers like skin and mucous membranes. Step 3: Cellular defenses include immune cells like macrophages and natural killer cells. Step 4: These defenses are present from birth and do not require prior exposure to pathogens. Step 5: Choice C is true as innate immunity encompasses both physical and cellular defenses, making it the correct answer. Other choices are incorrect: A: Innate immunity does play a role in stimulating adaptive immunity through antigen presentation. B: It does not require prior exposure to function, as it is a rapid and non-specific response. D: Innate immunity is not antigen-specific; adaptive immunity is responsible for antigen-specific responses.

Correct Answer: B

Rationale: Granzyme entering a target cell activates apoptosis pathways by inducing cell death. Firstly, granzyme activates caspases leading to cell death. Secondly, it triggers DNA fragmentation and cell shrinkage. Lastly, it enhances membrane blebbing and apoptotic body formation. The other choices are incorrect because granzyme does not neutralize toxins, inhibit cytokine secretion, or promote antigen presentation within a target cell.

Correct Answer: A

Rationale: The correct answer is A because memory function in adaptive immunity allows for rapid and stronger responses to previously encountered antigens. This is achieved through the presence of memory cells, such as memory B and T cells, which can quickly recognize and respond to specific pathogens upon re-exposure. This leads to a faster and more efficient immune response, providing better protection against future infections. Choice B is incorrect because direct killing of pathogens without prior activation is a function of innate immunity, not adaptive immunity. Choice C is incorrect as enhanced cytokine secretion is not the primary advantage of memory function. Choice D is incorrect because while memory function provides protection against previously encountered antigens, it does not confer resistance to all infections without exposure.