Vaccination works by producing
A{'text': 'Innate immunity', 'label': 'A'}
B{'text': 'Active immunity through memory B and T cells', 'label': 'B'}
C{'text': 'Non-specific defence', 'label': 'C'}
D{'text': 'Passive immunity via injected antibodies', 'label': 'D'}
Answer & Solution
Correct answer: B. {'text': 'Active immunity through memory B and T cells', 'label': 'B'}
1. Vaccines contain antigens (weakened pathogens, killed pathogens or protein fragments).
2. Exposure primes the immune system, generating memory B and T cells.
3. On re-exposure, memory cells produce a fast, strong secondary response.
4. This constitutes ACTIVE ACQUIRED immunity; passive immunity uses pre-formed antibodies.
_Source: NCERT Class 12 Biology, Ch 7 "Human Health and Disease", §7.2_
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