alleryAneuploidy refers to:
AGain or loss of one or a few chromosomes (e.g., trisomy 21, monosomy X)
BLoss of the Y chromosome only
CThe presence of an extra full set of chromosomes
DSingle-base mutation
Answer & Solution
Correct answer: A. Gain or loss of one or a few chromosomes (e.g., trisomy 21, monosomy X)
**Aneuploidy** = gain or loss of *one or a few* chromosomes due to failed segregation (non-disjunction).
**Examples:** trisomy 21 (Down), monosomy X (Turner), trisomy XXY (Klinefelter).
**Polyploidy** = whole-set increase (more common in plants).
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