$A$ normal-sighted man, whose father was color-blind, marries a woman whose father was also color-blind. They have their first child as a daughter. What is the probability that this child will be color-blind (in $\%$)?

Study the given pedigree chart and select the correct option for the given questions.
$(1)$ Is the trait recessive or dominant?
$(2)$ Is the trait sex-linked or autosomal?

Study the given pedigree chart.

$A$ woman carrying two genes for haemophilia and one gene for colour blindness on one of her $X$ chromosomes marries a normal man. What will be the phenotype of the progeny?

Pick out the correct statements.
$(1)$ Haemophilia is a sex-linked recessive disease.
$(2)$ Down's syndrome is due to aneuploidy.
$(3)$ Phenylketonuria is an autosomal recessive gene disorder.
$(4)$ Sickle cell anaemia is an $X$-linked recessive gene disorder.

With respect to phenylketonuria,identify which statement is not correct.