Question

True-breeding pea plants with smooth peas are crossed with true-breeding pea plants with wrinkled peas. All individuals of the first-generation have smooth peas.
Using S and s, what is the genotype of each parent?

If the first-generation offspring are crossed with each other, what will the second-generation phenotype be?

Answer 1

Mendel crossed the dominant smooth seeded pea plant (SS) with the recessive wrinkled seeded pea plant (ss). The F 1 generation produced the heterozygous smooth seeded plants with a genotype Ss. When two heterozygous pea plants (Ss) are crossed in the F2 generation represented by Ss x Ss, the gametes formed are S and s. In the second generation, out of the total offspring produced, 3 have the smooth seeded phenotype and 1 has wrinkled seed phenotype. Thus the phenotypic ratio is 3: 1 with one out of four plants being a wrinkled seeded pea plant.