Assertion: The principle of immunisation or vaccination is not based on the property of ‘memory’ of the immune system.
Reason: In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Assertion is false but Reason is true.
Acquired immunity has memory. The first meeting with a pathogen gives a weak primary response; the next meeting with the same pathogen gives a quick and strong secondary response. Vaccination uses this property.
Assertion: The principle of immunisation or vaccination is not based on the property of ‘memory’ of the immune system. — False. The book says vaccination is based on the memory of the immune system. The word “not” makes the statement false.
Reason: In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body. — True. A vaccine carries antigens or a weakened or killed pathogen. The body makes antibodies and also memory B- and T-cells, which recognise the real pathogen quickly later.
NCERT Extract:
Vaccination and Immunisation – “The principle of immunisation or vaccination is based on the property of ‘memory’ of the immune system. In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body. The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection. The vaccines also generate memory – B and T-cells that recognise the pathogen quickly on subsequent exposure and overwhelm the invaders with a massive production of antibodies.”