Answer: The body produces its own antibodies after exposure to antigen.
- A Receiving ready-made antibodies transferred from another source or organism
- B The body produces its own antibodies after exposure to antigen
- C Immunity that is already present in an individual from the moment of birth
- D Antibodies passed from mother to fetus across the placental barrier
Correct answer: B. The body produces its own antibodies after exposure to antigen
Explanation: Active immunity: the body's own immune system makes antibodies in response to antigen exposure. This can be natural (infection) or artificial (vaccination). Active immunity is long-lasting because memory cells are formed.
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.