Question

What is the ratio of dihybrid test cross?

Answer 1

Dihybrid test cross:

1. A test cross is done to determine the genotype of the heterozygous dominant or homozygous parent.
2. In a test cross the dominant parent (heterozygous or homozygous) is crossed with the homozygous recessive parent.
3. Dihybrid cross is the cross between two different genes that differ in two observed traits.

The ratio of dihybrid test cross:

1. Consider “Y” for yellow seed colour and “y” for green seed colour, “R” for round shaped seeds and “r” for wrinkled seed shape.
2. Thus, the parental genotype will be “YYRR” (yellow-round seeds) and “yyrr” (green-wrinkled seeds)
3. In a dihybrid test cross, when the dominant parent of F1 generation is crossed, it gives 1:1:1:1 ratio.
4. Further, on self pollination of two heterozygous genotype gives 9:3:3:1 ratio in F2 generation.