Question

In pea plant, spherical seeds (S) is dominant to dented seeds(s). In a genetic cross of two plants that are heterozygous for seed shape trait, what fraction of the offspring should have spherical seeds ?

Answer 1

Here two plants that are heterozygous for the seed shape trait are crossed. We can make the punnett square for the self cross of heterozygous plant having spherical seed (S) as the dominant trait and dented seed (s) as the recessive trait.

Parents: Ss x Ss

Gametes: S and s (for both the parents)

The punnett square is as follows

	S	s
S	SS	Ss
s	Ss	ss

Phenotypic ratio obtained was 3:1:: spherical seeds : dented seeds

Thus, 3/4 of the offspring will have spherical seeds.