A woman who is a carrier of red-green colour blindness (X-linked recessive) has children with a man of normal vision. What is the chance that a son is colour blind?
Answer and explanation
Correct answer: B. 50%
A son receives his X from his mother, who passes on the colour-blind allele half of the time.
Answer: 50%.
Why not the others: 0%: she can pass on the affected X to her sons. 25%: that is the chance for any child. 100%: only half of her X chromosomes carry the allele.
Answer: 50%.
Why not the others: 0%: she can pass on the affected X to her sons. 25%: that is the chance for any child. 100%: only half of her X chromosomes carry the allele.
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