Question

Consider the sequence of activities given below:

i. Lymphocytes produce antibodies

ii. Phagocytes engulf the antigen that have been "marked" by the antibodies

iii. Antigen enters the body

iv. Lymphocytes recognise antigen

v. Antibodies render the antigen harmless

Which of these is the correct order in which the above occur?

• A. i, iii, iv, ii, v
• B. iii, iv, i, v, ii
• C. iii, i, v, ii, iv
• D. i, iv, v, iii, ii

Answer 1

The correct option is B

iii, iv, i, v, ii

Once an antigen enters the body, the lymphocytes first recognise it. Then, they produce antibodies to render it harmless. This happens if it is the first time the person has been "infected" by the antigen. Once the antibodies render the antigens harmless, the phagocytes engulf them.