Question

The pure tall plant is crossed to dwarf plant. $F_1$ generation consists of only tall plants while $F_2$ generation has both tall and dwarf in the ratio of 3: 1. The phenomenon is due to

• A. Dominance
• B. Codominance
• C. Incomplete dominance
• D. Heredity.

Answer 1

Answer: (A)

Dominance

Height in pea plant is determined by two alleles, T and t. Pure tall plants have genotype TT while pure dwarf has genotype tt.

Here the F${}_1$ generation has a genotype of Tt ( heterozygous ). Allele T is dominant over t and result in all the 'Tt' offspring as tall. Dominance is the condition in which the effect on the phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive.

F${}_2$ generation has offspring as TT, Tt and tt in the ration of 1:3:1. As we can see again, allele 'T' is dominant in case of the heterozygous condition.

So, the correct option is 'Dominance'.