What is back cross? Explain with example

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Detailed Solution

A back cross is a type of genetic cross used to identify or confirm the genotype of a hybrid organism.

Definition:

A back cross is the mating of an F1 hybrid (heterozygote) with one of its parents or an individual genetically similar to one of its parents. Its purpose is to determine the genotype of the hybrid organism.

Example: Consider two parent plants:

Parent 1 (P1): Homozygous dominant (TT) – Tall

Parent 2 (P2): Homozygous recessive (tt) – Dwarf

When crossed:

F1 generation (Tt) – All tall plants.

Now performing the back cross:

F1 (Tt) × Parent 1 (TT): Offspring: TT, Tt → All Tall

F1 (Tt) × Parent 2 (tt): Offspring: Tt (Tall) and tt (Dwarf) → 1:1 ratio

The back cross helps determine whether the F1 hybrid is heterozygous by analyzing the traits of its offspring. It is often used in genetics to confirm parental genotypes and in breeding programs for desired traits.

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