Question

Define the term Test cross.

Answer 1

In genetics, a test cross, first introduced by Gregor Mendel, is used to determine if a group exhibiting a dominant trait is homozygous or heterozygous for that trait. More simply put, test crosses determine the genotype of an individual with a dominant phenotype.

Answer 2

Dear Student,

◆ Test cross -

• Test cross is cross between individual with unknown genotype and an individual with a phenotypically recessive individual.
• It helps ti determine zygosity (homozygous/heterozygous) of individuals showing dominant traits.

# Designing a test cross -

Let's take a cross between F1 hybrid of round and wrinkled seeds with homozygous plant with wrinkled seeds.

• Parents : F1 hybrid (Rr) × Homozygous recessive (rr)
• Gametes : R & r × r
• Progeny : Round seeds (Rr), Wrinkled seeds (rr)

Here, ratio of round seeds : wrinkled seeds is 1 : 1.

Hope this helps you...