Consider the following chromosomes and if they are affected by hernophilia.
X = unaffected X chromosome, x = X chromosome affected by hemophilia, and Y = Y chromosome.
If an Xx female and XY male have children, what fraction of their offspring will have an affected chromosome, and what fraction is likely to be affected by hemophilia?
(1 point)
1/2 and 1/4
1/2 and 1/3
1/3 and 1/4
1/4 and 1/2
Hemophilia is a sex-linked recessive trait that is carried on the X chromosome.
The possible genotypes for the female parent (Xx) are X^X and X^x, where X^X represents the unaffected X chromosome and X^x represents the X chromosome affected by hemophilia.
The possible genotypes for the male parent (XY) are X^Y and Y, where X^Y represents the unaffected X chromosome and Y represents the Y chromosome.
When the X^x chromosome from the female parent combines with the X^Y chromosome from the male parent, the resulting offspring could be XX^x, X^XX, XY, or X^Y.
Out of these possible genotypes, only XX^x and XY would have an affected chromosome (X^x affected by hemophilia). Therefore, the fraction of offspring that will have an affected chromosome is 2 out of 4 (or 1/2).
Now, out of these affected offspring, only XX^x would be affected by hemophilia. Therefore, the fraction of offspring likely to be affected by hemophilia is 1 out of 4 (or 1/4).
So the correct answer is: 1/2 and 1/4.