In a cross between two tall pea plants some of the offsprings produced were dwarf. Show with the help of Punett square how this is possible.

Explanation

Dwarfness (recessive trait) has appeared in the progeny, the tall pea plant must be heterozygous for tallness, i.e., its genotype is Tt.

The phenotypic ratio is 3 tall : 1 dwarf since tallness is dominant over dwarfness, the homozygotes (Tt) as well as the heterozygotes (Tt) are tall. The recossive trait is expressed only under homozygous conditon (tt) and hence appears only in one-founth of the progeny.