Home / IB DP Biology- C3.2 Defense against disease- IB Style Questions For HL Paper 1A

IB DP Biology- C3.2 Defense against disease- IB Style Questions For HL Paper 1A -New Syllabus

IBDP Biology HL Paper 1 - All Chapters

Question

Which type of cell belongs to the innate (non-specific) immune system?

A. Phagocytes
B. B-lymphocytes
C. T-lymphocytes
D. Helper T-cells

▶️ Answer/Explanation
The innate immune system gives a rapid, non-specific response. Phagocytes (such as macrophages and neutrophils) engulf and digest pathogens immediately, so they are part of innate immunity. B-lymphocytes, T-lymphocytes, and helper T-cells are part of the adaptive immune system.
✅ Answer: (A) Phagocytes

Question

Which function is primarily associated with helper T-cells in the immune system?

(A) Phagocytosis of pathogens
(B) Activation of other cells in the immune system
(C) Antibody production
(D) Retention as memory cells
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathbf{B}} \)

Helper T-cells coordinate the immune response by releasing cytokines that activate B-cells, cytotoxic T-cells, and phagocytes. Their main role is to regulate and stimulate other immune cells rather than directly producing antibodies or engulfing pathogens.

Question

Which of the following will cause the production of antibodies during an infection?

(A) Conversion of fibrinogen to fibrin by thrombin.
(B) B-cell activation by helper T-cells and antigens.
(C) Plasma cell activation by platelets.
(D) Activation of phagocytes by infected body cells.
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathbf{B}} \)

B lymphocytes recognize a specific antigen and are activated by helper T-cells. They then differentiate into plasma cells, which produce large quantities of antibodies specific to that antigen.

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