Question

When chickens with splashed white feathers are crossed with black-feathered birds, their offspring are all slate blue (Blue Andalusian). When Blue Andalusians are crossed with themselves, they produce splashed white, blue and black offspring in the ratio 1:2:1 respectively. Show the results of the crosses below, phenotypically and genotypically.

Answer 1

I did this question before

Answer 2

The given cross is an example of incomplete dominance. It is a type of genetic interaction in which dominant allele is mot able express itself completely over the recessive allele.

For instance, let us take W and w be the alleles of the gene responsible for feather colors.

W is not completely dominant over w due to which the gene produces three phenotypes.

WW- homozygous dominant produces white feather.

Ww- heterzygous produces slate blue feathers.

ww- homozygous recessive produces black feathers.

So, the genotypes of parents are WW (splashed white) and ww (black). They cross to produce all slate blue offspring, that is, Ww.

On self-crossing Ww, three types of genotypes will be produced in the ratio 1 (WW): 2 (Ww): 1 (ww). Thus, the cross will produce phenotype in the same ratio, that is, 1 (white): 2 (slate blue): 1 (black).