Question

Read the passage and answer the following question.

The graph illustrates the data from an experiment in which antibody levels for two different antigens, A and B were measured following exposure to these antigens. Antibodies play a crucial role in the human body's defense against disease.

Which of the following causes the large peak upon secondary stimulation?

• A. Proliferation and differentiation of memory cells to secrete antibody
• B. More antigen in the organism
• C. T cell activation
• D. Passive immunity
• E. None of these

Answer 1

The correct option is A Proliferation and differentiation of memory cells to secrete antibody

The primary immune response is observed when the person is vaccinated. There is the production of the antibodies by the plasma cells which are activated by the T-cells on recognising the antigen. When the body encounters the same antigen for the second time, there is secondary response generated. The B-cells and T-cells are already present against the antigen and the other immune cells are rapidly activated. The memory cells remember the same antigen. The memory cells proliferate and produce a number of specific antibodies which can fight against the same antigen.

Thus, the correct answer is option A.