Question

If a polygenic trait is controlled by three gene pairs then how many offspring in f2 generation will show parental phenotype

Answer 1

Answer:

Explanation:

100%

Answer 2

Answer:

20 offsprings in F2 generation will show parental phenotype.

Explanation:

What is a polygenic inheritance:

• Polygenic inheritance is a sort of divergence from Mendelian inheritance in which more than two genes control a character.
• The genes involved are larger in number or quantity, but they are still modest in size.

Result:

The trait is controlled by three genes. The genes are named A, B and C for dominant and a,b and c for recessive.

The parent generation (P1) → AABBCC X aabbcc

Gametes → ABC, abc

F1 generation →AaBbCc

Now there is selfing of F1 progeny,

P2 generation →AaBbCc X AaBbCc

We use a formula to calculate the number of offsprings where n is the number of genes.

Here the number of genes is three. So, 4³ = 64

The phenotypic ratio from the above cross is 1:6:15:20:15:6:1

There are three dominant alleles in the F1 phenotype. In the F2 generation, 20 of the total (sixty four) individuals have the same phenotypic as the F1 generation.