All test crosses are considered as backcrosses, but all backcrosses are not the test crosses.• During backcross, F1 hybrid is crossed back with any of the parents, eit her homozygous or heterozygous. However, during test cross, F 1 hybrid is always crossed back with the recessive parent.

Difference between Test Cross and Back Cross

Test Cross:
Test cross is a breeding technique used to determine the genotype of an individual showing a dominant phenotype. It involves crossing the individual with a homozygous recessive individual to reveal the genotype of the dominant individual. This technique is commonly used in genetics to determine whether an organism with a dominant phenotype is homozygous or heterozygous for a particular trait.

Key Points:
- Test cross is used to determine the genotype of an individual showing a dominant phenotype.
- It involves crossing the individual with a homozygous recessive individual.
- The purpose is to reveal the genotype of the dominant individual.

Back Cross:
Back cross is a breeding technique used to transfer a desirable trait from a hybrid organism back into one of its parent lines or a parental strain. It involves crossing the hybrid with one of its parent organisms, which can be either homozygous or heterozygous for the desired trait. The aim of back cross is to create offspring that retain the desired trait while having a genetic background similar to the parent line.

Key Points:
- Back cross is used to transfer a desirable trait from a hybrid organism back into its parent line.
- It involves crossing the hybrid with one of its parent organisms.
- The purpose is to create offspring that retain the desired trait while having a genetic background similar to the parent line.

Differences:

1. Purpose:
- Test cross is used to determine the genotype of an individual showing a dominant phenotype.
- Back cross is used to transfer a desirable trait from a hybrid organism back into its parent line.

2. Cross Type:
- Test cross involves crossing the individual with a homozygous recessive individual.
- Back cross involves crossing the hybrid with one of its parent organisms.

3. Trait Expression:
- Test cross reveals the genotype of the dominant individual.
- Back cross aims to create offspring that retain the desired trait.

4. Genetic Background:
- In test cross, the genetic background is not a primary concern, as the main focus is on determining the genotype of the individual.
- In back cross, the genetic background is important to ensure that the offspring have a similar genetic background to the parent line.

Conclusion:
In summary, test cross and back cross are both breeding techniques used in genetics. Test cross is used to determine the genotype of an individual showing a dominant phenotype, while back cross is used to transfer a desirable trait from a hybrid organism back into its parent line. The cross types, purpose, trait expression, and genetic background differ between the two techniques.