Answer: Secondary is faster and produces more antibodies due to memory cells; IgG predominates in secondary; IgM predominates in primary.
- A The primary response is generally faster and produces a noticeably greater quantity of antibodies overall in standard practice
- B Secondary is faster and produces more antibodies due to memory cells; IgG predominates in secondary; IgM predominates in primary
- C Both the primary and secondary immune responses are largely similar to one another in most measurable respects under most conditions encountered
- D The primary response involves mainly B lymphocytes, while the secondary response involves mainly T lymphocytes as frequently observed in practice
Correct answer: B. Secondary is faster and produces more antibodies due to memory cells; IgG predominates in secondary; IgM predominates in primary
Explanation: Primary response (first exposure): slow (days), smaller antibody titre, IgM predominates first then IgG. Secondary response (re-exposure): rapid (hours-1-2 days), much higher antibody titre, mainly IgG, persists longer. This is the basis of vaccination booster doses.
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.