Answer: passive.
- A passive
- B active
- C innate
- D purely cellular
Correct answer: A. passive
Explanation: Ready-made maternal antibodies give the foetus passive immunity.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.