Q.What is back cross ?

A back cross is a cross between an F1 hybrid and one of its two parents, used in genetics to test genotype and in breeding to transfer desirable genes.

Working

A back cross is defined as a cross between an F1 hybrid individual and either of its two parents (or an individual with a genotype identical/similar to one of the parents). It serves two major purposes:

1. Genetic analysis -- A particular form of back cross called the test cross involves crossing the F1 hybrid specifically with the homozygous recessive parent. Because the recessive parent contributes only recessive alleles, the phenotypic ratio of the offspring directly reveals the genotype (and the types/ratio of gametes) of the F1 individual -- this is the classic method used to determine whether an organism showing a dominant phenotype is homozygous dominant or heterozygous. …