The number of pair$(s)$ of sex chromosomes in the zygote of humans is

The genotype of a green-stemmed tomato plant is denoted as $GG$ and that of a purple-stemmed tomato plant as $gg$. When these two are crossed:
$(i)$ What colour of stem would you expect in their $F_1$ progeny?
$(ii)$ Give the percentage of purple-stemmed plants if $F_1$ plants are self-pollinated.
$(iii)$ In what ratio would you find the genotypes $GG$ and $Gg$ in the $F_2$ progeny?

Why do all the gametes formed in human females have an $X$ chromosome?

$A$ very small population of a species faces a greater threat of extinction than a larger population. Provide a suitable genetic explanation.

Two pink coloured flowers on crossing resulted in $1$ red,$2$ pink and $1$ white flower progeny. The nature of the cross will be

How can the chromosomes be identified?