Question

A homozygous tall plant (TT) bearing red coloured(RR) flowers is crossed with a homozygous dwarf plant(tt) bearing white flowers(rr):

(a) Give the genotype and phenotype of the F1 generation.

(b) Give the possible combination of the gametes that can be obtained from the F1hybrid.

(c) Give the dihybrid ratio and the phenotype of the offsprings of F2 generation when two plants of the F1 generation above are crossed.

Answer 1

Genotype

1. Genetic constitution of an organism with regard to a character.
2. All genotypes are not phenotype.

Phenotype

1. The external appearance of an character is called its phenotype.
2. All phenotypes are genotype.

(a) Genotype of F1 generation plants: TtRr

Phenotype of F1 generation plants: Tall and red-coloured flowers.

(b) The possible combinations are shown below with the help of a punett square

Phenotypes of offspring obtained in the F2 generation:

1. Tall plants with red flowers
2. Tall plants with white flowers
3. Dwarf plants with red flowers
4. Dwarf plant with white flowers

Dihybrid ratio

1. It is a ratio which is obtained in F2 generation.

(c) The phenotypic ratio of F1 and F2 generation is given below:

F1 generation=3:1

F2 generation= 9:3:3:1