The Difference Between Back Cross And Test Cross
When breeding plants or animals, there are different ways to determine the genotype of the offspring. Two of these methods are backcross and testcross. While both methods are similar, they differ in the way they are conducted and the information they provide.
Backcross
A backcross is a breeding method where an organism is crossed with one of its parents or an organism that is genetically similar. This method is used to introduce or reinforce a specific gene or trait in the offspring. The offspring will inherit half of their genetic material from the parent and half from the organism that is being introduced.
Backcrossing is used to create hybrid plants or animals that have the desired traits of the parent and the introduced organism. It is important to use an organism that is genetically similar to ensure that the offspring have the desired traits.
Test Cross
A test cross is a breeding method where an organism that is homozygous recessive is crossed with an organism with an unknown genotype. The goal of a test cross is to determine the genotype of the unknown organism.
If the organism is homozygous dominant, all of the offspring will show the dominant trait. If the organism is heterozygous, half of the offspring will show the dominant trait and half will show the recessive trait.
Testcrossing is a way to determine the genetic makeup of an organism that has an unknown genotype. It is useful in determining whether a dominant trait is homozygous or heterozygous.
Conclusion
While backcrossing and testcrossing are similar, they are used for different purposes. Backcrossing is used to introduce or reinforce specific traits in offspring, while a test cross is used to determine the genotype of an unknown organism.
Understanding the differences and benefits of each breeding method can be helpful in creating hybrid plants or animals with desired traits and determining the genotype of organisms in genetic research.
Table difference between back cross and test cross
| Back cross | Test cross |
|---|---|
| It involves crossing a hybrid organism with one of its parent organisms. | It involves crossing an organism with a homozygous recessive organism to determine the genotype of the first organism. |
| It is used to increase the frequency of a desired trait in a population. | It is used to determine the genotype of an organism with a dominant phenotype. |
| The phenotype ratio of the offspring is predictable. | The phenotype ratio of the offspring is used to determine the genotype of the first organism. |
| It is denoted as BB x Bb or AA x Aa. | It is denoted as AA x aa or Aa x aa. |