Question

Tommorow is My Exam HELP

In a cross between plants with purple flowers and plants with white flowers the off springs

of F1 generation all had white flowers. When the F1 generation was self – crossed, it was

observed in the F2 generation that out of 100, 75 flowers were white. Make a cross and

answer the following :-

(a) what are the genotypes of the F2 progeny?

(b) What is the ratio of White : Purple flowers in the F2 generation ?

Answer 1

Let the plants with genotype Wp (white flower variety obtained in F1 generation) where white is dominant are self crossed.

The cross is given below:

	W	p
W	WW	Wp
p	Wp	pp

As W is dominant white, the ratio of white and purple in F2 generation will be 3:1. This means among 100, 75 flowers are white and 25 are purple.

1. The genotypes of plants in F2 generation are WW (homozygous white), Wp (heterozygous white) and pp (purple).
2. The ratio of white and purple flowers in F2 generation is 3:1.