Question

Birds, unlike mammals, have a sex determination system in which females have Z and a W chromosome (ZW), while males have two copies of Z (ZZ). Another fun fact: most bird species, including chickens, do not have penises. This makes it hard to determine the sex of baby chicks! There’s a gene required for pigmentation located on Z. The “barred” allele (b) of this gene is recessive to the black allele (B). If you would like to easily determine the sex of your chicks based on their color, what cross might you make?

Answer 1

in chicken females are ZW and males are ZZ.

Zb-barred, ZB-black

it is possible to determine the sex of the progeny just by looking at the phenotype the cross between a black female and a barred male.

if the mother is ZBW and the father is ZbZb

then ZBW * ZbZb

	ZB	W
Zb	ZBZb (black male)	ZbW ( barred female)
Zb	ZBZb (black male)	ZbW( barred female)

here the female progenies will all be barred and the male progenies will all be black.

so by looking at the phenotype we can determine whether the progenies are male or female.