Question

Define and design a test - cross.

Answer 1

Test cross means crossing of F1 generation with resistive parent.

It is a type of back cross.

There is further division of test cross:-

[1] Monohybrid test cross :- The progeny obtained from the Monohybrid test cross are in equal proportion,means 50% is dominant phenotype and 50% is recessive phenotype.

[2] Dihybrid test cross:- The progeny is obtained from Dihybrid test cross are of 4 types and each of them is 25%

Answer 2

Answer:

• Test cross is a cross between an organism with unknown genotype and a recessive parent. It is used to determine whether the individual is homozygous or heterozygous for a trait.  

• If the progenies produced by a test cross show 50% dominant trait and 50% recessive trait, then the unknown individual is heterozygous for a trait. On the other hand, if the progeny produced shows dominant trait, then the unknown individual is homozygous for a trait.