consider the followin chromosomes and if they are affected by hemophila.

Question

X=unaffected X chromosomes, x=X chromosomes affected by hemophili, and Y=Y chromosme.
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.
a. 1/4 and 1/4
b. 1/4 and 1/2
c. 1/2 and 1/3
d. 1/2 and 1/4

Answer 1

To determine the fraction of their offspring that will have an affected chromosome, we need to consider the genotype of each parent.

The female is Xx, which means she carries one unaffected X chromosome (X) and one affected X chromosome (x).

The male is XY, which means he carries one unaffected X chromosome (X) and one Y chromosome (Y).

When they have children, each parent randomly contributes one of their sex chromosomes to the offspring.

Possible combinations are:

- Female contributes X chromosome, Male contributes X chromosome: result is XX (unaffected female)
- Female contributes X chromosome, Male contributes Y chromosome: result is XY (unaffected male)
- Female contributes X chromosome affected by hemophilia (x), Male contributes X chromosome: result is Xx (female affected by hemophilia)
- Female contributes X chromosome affected by hemophilia (x), Male contributes Y chromosome: result is XY (unaffected male)

So, 1/4 of their offspring will have an affected chromosome (Xx or XY), and 1/4 of their offspring will actually be affected by hemophilia (Xx).

Therefore, the correct answer is d. 1/2 and 1/4.