Abigayle is a carrier for hemophilia. her husband, claude, does not have the disorder. if abigayle and claude have children, which of the following statements will be true? none of the children will have hemophilia. there is a 100 percent chance that a boy will have hemophilia. there is a 50 percent chance that a girl will be a carrier. there is a 25 percent chance that a girl will have hemophilia.

Hemophilia is a recessive sex-linked disorder present only in the x-chromosome.

Hence in females, it takes two faulty genes to develop the disease.  If one of the two X-chromosomes (out of XX) is normal, the female is a carrier.

In males, if the X-chromosome (out of XY) is defective, he will develop hemophilia.  In other words, there are no male carriers.

In the given case, father does not have hemophilia, so he has a normal X-chromosome. (XY)

The mother is a carrier, so she has one faulty gene out of two (Xx) where x is the hemophilia related gene.

A punnett square will explain all possible outcomes:

     X   YX   XX  XY   (healthy)x   Xx  xY     (carrier or has hemophilia)
    (F)  (M)
Where 
x=gene-carrying hemophiliaXX=healthy female (25% out of 50% females)XY=healthy male (25% out of 50% males)Xx=female carrier (25% out of 50% females)xY=male with hemophilia (25% out of 50% males)
Now examine the given statements:
None of the children will have hemophilia.
     (false because a son could develop hemophilia)
There is a 100 percent chance that a boy will have hemophilia.
    (false because given a boy,  25% out of 50%=50% chance he will develop hemophilia)
There is a 50 percent chance that a girl will be a carrier.
    (given a girl, 25% out of 50%=50% she will be a carrier, so TRUE)
There is a 25 percent chance that a girl will have hemophilia.
    (given a girl, she will be either a carrier (50%) or healthy, so 0% that she develops hemophilia)

Dna strands are split apart to allow an opening for replication. the opening has two replication forks so synthesis goes toward them in 5' to 3' direction.