Paper II — 2025 March (Supplementary (SAY)) (2019 Scheme) — Qxx
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Paper II
2025 March (Supplementary (SAY)) (2019 Scheme) · 100 marks · 180 min
Question
A: Influenza viruses are responsible for pandemics over the years
R: Antigenic shift is common is these viruses
a) Both A and R are true and R is the correct explanation of A
c) A is true but R is false
b) Both A and R are true and R is not the correct explanation of A
d) A is false but R is true
Qxx1.8 marksMCQs (Multi)
Answer
- [x] a) Both A and R are true and R is the correct explanation of A
Assertion is true: influenza viruses have indeed been responsible for pandemics over the years (e.g., 1918, 1957, 1968, and 2009).
Reason is true and correctly explains the assertion: antigenic shift — a major, abrupt change in surface glycoproteins arising from reassortment of gene segments between two different influenza A strains (possible given the segmented genome), occurring only in influenza A — produces a novel viral subtype to which the population has little/no pre-existing immunity, directly explaining why influenza specifically (rather than most other respiratory viruses) has genuine pandemic potential, distinguishing it from the more limited, seasonal-epidemic-only impact of antigenic drift.
