Question

a cross is performed between a bird that is homozygous for red feathers and a bird that is homozygous for blue feathers. purple offspring result due to incomplete dominance. then, two of the purple offspring are crossed. what proportion of the offspring from the second cross will be purple? 1 in 4 2 in 4 3 in 4 4 in 4

Explanation:

Step1: Determine the genotypes of the parents

Let \(R\) represent the allele for red feathers and \(B\) represent the allele for blue feathers. The first - cross parents are \(RR\) (homozygous red) and \(BB\) (homozygous blue). The offspring of the first cross (due to incomplete dominance) will have the genotype \(RB\) (purple feathers).

Step2: Perform the second - cross ( \(RB\times RB\) )

Using the Punnett square method:

Gametes of Parent 1	Gametes of Parent 2
\(R\)	\(RR\) (red)	\(RB\) (purple)
\(B\)	\(RB\) (purple)	\(BB\) (blue)

The genotypes of the offspring are \(RR:RB:BB = 1:2:1\)

Answer:

2 in 4