Arecessive gene for red-green color blindness is located on the x chromosome in humans. assume that a woman with normal vision (her father is color-blind) marries a color-blind male. what is the likelihood (give a percentage) that this couple's first son will be color-blind?

a. 0%
b. 25%
c. 50%
d.75%
e. 100%

A=0%

The mother allele is Xx and the XY.

The mother and father are heterozygous for the traits.

Explanation:

This is because the mother (Xx) carries a trait for color blindness. Which she inherited from her father who is color blinded that is XY.

The x -chromosomes carries the color blinded trait.

When she is crossed with her color blinded male, the first boy XY will not be color blinded :

Because the boy will pick Nomal X chromosomes from the mother, and and Y chromosomes from the father to form XY. The male sex chromosomes.

Since this is a monohybrid cross,

4 offspring are produced 2 girls and 2 boys .

Genotypes-XY(first boy), Yx Xx, xx .

This a factor of 4 so the first child probability is ZERO. Since 0 divided by 4 = 0

Since no allele with color blinded gene is inherited.

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