Ans.
Heterozygous plants are those plants that have two different alleles for a particular gene or trait. The garden pea plant shows two alternative seed shape, round and wrinkled. The allele for round shape is denoted by 'R", which is dominant trait over recessive allele for wrinkled shape ('r').
When plants heterozygous for round seeds (Rr) are self-crossed, two types of gametes are formed, R and r. The resulting offspring show both round (75%) and wrinkled (25%) seeds.
Thus, 25% offspring will show wrinkled seeds as there is one wrinkled plant out of four offspring plants as shown in Punnett square below:
