Question

Complete the punnett square below of a cross between a carrier mother (a female who carries one copy of the recessive allele and so appears normal herself) and a non-hemophiliac father.

Answer 1

Hemophilia is a genetic disorder that inherited by X-linked recessive pattern. A daughter needs 2 genes to have the disease(or 1 gene to become carrier) but a son only needs to get 1 defect genes from his mother(X  gene in male must come from mother). If Xh defected gene and X normal genes, the punnett square would be:

                       Father(XY)
                        X         Y
Mother   Xh    XhX      XhY    ------>XhX= carrier , XhY= sick
 (Xh X)     X     XX        XY      ------>healthy