Question

Which symbol is used to label a male that expresses a sex-linked disorder on a pedigree

Answer 1

Filled in square is the answer.

Answer 2

Circle is for female & square is used for male

If its white means the disease hasn't shown
If its black means the person is sick

And if its half black and half white means that person is carrier ( you will see this only in autosomal / sex linked diseases that are RECESSIVE )

In autosomal male and female catch tye disease at equal rates

But in sex linked only a gender is getting it more ..

In y-linked a father that is sick will pass tye disease for all of his sons ( they are all black squares )

Hope i helped ..