Question

Three generations of a family afflicted with hemophilia are illustrated in the pedigree chart. Family members used the pedigree chart and the laws of genetics to predict the occurrence of the disease. From the information in the chart, one can determine that hemophilia is
A) sex-linked and occurs more in males than females.
B) autosomal and occurs equally in males and females.
C) sex-linked and no pattern of inheritance can be predicted.
D)autosomal and occurs more frequently in males than females.

Answer 1

The answer is A. Sex-linked traits are more often expressed in males because they are typically carried by the X chromosome and they are also typically recessive. Males only inherit one X chromosome, so if the one they inherit is linked to the disease, they will express it no matter what. Females, on the other hand, can be carriers if they inherit one X chromosome with the disease. This is because their other X chromosome can be normal, which would dominate the expression of the disease on their other X chromosome. 

Answer 2

The answer is A for this question.