Hardy–Weinberg for an X-linked trait
In a population at Hardy–Weinberg equilibrium, 8% of males have red–green color blindness, an X-linked recessive trait. About what percentage of females are color-blind?
Answer A: explanation for every choice
A
Correct. Male frequency equals the allele frequency, q = 0.08. Affected females need two copies: q² = 0.0064, or 0.64%.
B
This halves the male frequency.
C
This assumes females are affected as often as males.
D
This is the carrier frequency, 2pq = 2(0.92)(0.08) ≈ 0.147.
TakeawayX-linked recessive: male frequency = q. Female frequency = q².
Equation usedHardy–Weinberg
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