One type of colorblindness is a recessive, sex-linked trait that is carried on the X chromosome. If a colorblind woman and a man who is not colorblind had children, what chance would there be that their son would be colorblind?

Question

mattyboyy · Answer

@Abhisar I'll post the options

mattyboyy · Answer

A) 25%

B) 0%

C) 100%

D) 50%

abhisar · Answer

Let's say that the genotype of the woman is $\sf X^cX^c$ and that of man is XY. Now draw a punnet square for a cross between them

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abhisar · Answer

Now what do you think should be the chances?

abhisar · Answer

There is one more thing, you can tell the answer without drawing the above square. To be  color blind the genotype should always be $\sf X^cX^c$ because it is a recessive disease and is carried on X chromosome. Now the question asks % for male child. A male child will always have a genotype of $\sf X^cY~or~XY$ in both the cases there would be one Y chromosome which would prevent the individual from being color blind.

mattyboyy · Answer

Ok I understnd @Abhisar

mattyboyy · Answer

So it would be 50% then

abhisar · Answer

How 50%?
No male child will have color blindness. This equals to what % ?

mattyboyy · Answer

Sorry lol I read it wrong @Abhisar