In humans, albinism is controlled by a recessive gene '$a$'. If both parents are known to be carriers $(Aa)$ for albinism, what is the probability of having $1$ normal and $3$ albino children in a family of $4$ (in $/256$)?

In a certain plant species,red flower colour is incompletely dominant to white flower colour (the heterozygote is pink) and tall stems are completely dominant to dwarf stems. If a tall pink plant $(TtRr)$ is crossed with a tall white plant $(TTrr)$,which one of the following types of plants would be produced in the offspring?

$A$ gene which suppresses the activity of another gene but does not lie on the same locus is called:

Which of the following is a sex-influenced character?

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

Select the incorrect statement from the following.