pedigree diagrams

Question 1

Give evidence from the diagram which suggests that muscular dystrophy is sex-linked

Answer 1

• if its sex linked , it predominately affects males
  -daughters inherit fathers X chromosome
  -males inherit y

So, if the diagram shows more shaded squares (representing males) than shaded circles (representing females), that suggests the disorder is sex-linked.

The affected male should not have affected sons, because they inherit the Y chromosome, not the X.