A normal woman whose father was colourblind marries a normal man. What kinds of children would be expected and in what proportion

Which one of the following symbols and its representation, used in human pedigree analysis is correct?

Pick out the correct statements.

$I.$ Haemophilia is a sex-linked recessive disease

$II.$ Down's syndrome is due to aneuploidy

$III.$ Phenylketonuria is an autosomal dominant gene disorder

$IV.$ Phenylketonuria is an autosomal recessive gene disorder

$V.$ Sickle cell anaemia is an $X$-linked recessive gene disorder

Sickle -cell anaemia has not been eliminated from the African population because it

A normal woman whose father was colourblind. marries a normal man. What kinds of children can be expected and in what proportion?

If a colour­blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour­blind is