In which cross an organism showing a dominant phenotype( genotype unknown) is crossed with the recessive parent?

Test cross

The correct answer is Option (1) -Test cross

In Test cross an organism showing a dominant phenotype (genotype unknown) is crossed with the recessive parent. In the case of dominant phenotype, by just looking at the morphology, it is difficult to find out whether the given plant is heterozygous or homozygous for dominance. In order to find the unknown genotype of the dominant character, a cross breeding is performed which is called test crossing. Here the unknown dominant character is crossed with the known recessive character, for example, tall plant (its genotype is not known) is crossed to dwarf (its genotype is known). In the cross, if the offsprings produced are of both dominant and recessive in equal ratio, the given plant is heterozygous for the said character. On the other hand, if the offsprings produced are all tall, then the tall plant is dominant homozygous. This type of crossing is employed to determine the heterozygosity or homozygosity of a suspected character.

If the dominant phenotype organism is homozygous dominant (e.g., AA), all offspring will show the dominant phenotype.

If the dominant phenotype organism is heterozygous (e.g., Aa), the offspring will exhibit a 1:1 ratio of dominant to recessive phenotypes.

This type of cross helps to reveal whether the dominant phenotype is due to a homozygous dominant or heterozygous genotype.

Out-crossing: This is the practice of mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4-6 generations.

Back cross: A genetic cross between a hybrid organism and one of the original parental types is called a back cross.