Meiosis in $AaBb$ will produce gametes:

$A$ couple has sons who are colourblind with $AB$ blood group. Identify the parents from the following.

In which plant was the lethal gene first observed?

Traits controlled by genes located on autosomes are said to be

Select the wrong pair from the following:

Which of the following statements are correct?
$i$. $X$ chromosome has a large amount of euchromatin.
$ii$. Heterochromatin is genetically inert.
$iii$. Both $X$ and $Y$ chromosomes are homologous.
$iv$. Crossing over does not take place in sex chromosomes in females.
Choose the correct option.