Question

Mendel crossed true-breeding tall pea plants
having purple flowers with short pea plants
having white flowers. Derive the genotype
and phenotype of the progeny.​

Answer 1

Explanation:

According to the law of dominance, a dihybrid cross between two pure-breeding varieties yields uniforms F

1

generation of all dominant offspring. Since here F

1

generation consists of short plants with violet flowers and tall plants with violet flowers in a 1:1 ratio; the dominant parent is not purebred. The absence of a dominant allele for flower color (violet) would make the phenotype of dominant parent tall with white flowers. The appearance of the recessive trait in F

1

generation (dwarfism) confirms the presence of one recessive allele in the dominant parent and makes it heterozygous for plant height (Tt). Since all F

1

generation has a violet flower, the dominant parent is homozygous for flower color. If the dominant parent was double heterozygous (TtWw), the F

1

generation would exhibit recessive traits of both plant height and flower color. But all F

1

generation exhibits violet flowers which confirm that the dominant parent is homozygous for flower color. Thus the correct answer is option C.