A Recessive Allele on the X Chromosome Is Responsible for Red-Green

question 55

Multiple Choice

A recessive allele on the X chromosome is responsible for red-green colour blindness in humans. A woman with normal vision whose father is colour blind marries a colour-blind male. What is the probability that this couple's first son will be colour blind?

• A) 1/4
• B) 1/2
• C) 2/3
• D) 3/4

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