In humans, there are two pairs of sex chromosomes.

Mendel observed a contrasting trait in relation to the position of flowers. Mention that trait.

$A$ pea plant with blue colour flower denoted by $BB$ is cross-bred with a pea plant with white flower denoted by $ww$.
$(a)$ What is the expected colour of the flowers in their $F_{1}$ progeny?
$(b)$ What will be the percentage of plants bearing white flower in $F_{2}$ generation,when the flowers of $F_{1}$ plants were selfed?
$(c)$ State the expected ratio of the genotypes $BB$ and $Bw$ in the $F_{2}$ progeny.

In pea plants, which trait is dominant between height and dwarfness?

Humans have a genetic basis for sex determination.
$(a)$ Besides humans,which organisms have a genetic basis for sex determination?
$(b)$ Which chromosomes are similar in human males and females?
$(c)$ What is the function of these types of chromosomes?

Give reasons for the following:
$(a)$ Traits acquired during the lifetime of an individual are not inherited.
$(b)$ All human beings belong to a single species.
$(c)$ Variations keep on accumulating during reproduction and do not disappear in the next generation.