A pea plant with red flowers is test crossed; half of the resulting progeny have red flowers, whereas the other half have white flowers. The genotype of the test-crossed parent was Rr.
Test cross is used to ascertain whether for a specific trait an individual is either homozygous or heterozygous.
In a typical test cross an organism (pea plants in this case) displaying a dominant phenotype (and whose genotype is to be ascertained) is crossed with the recessive parent in place of self-crossing.
The progenies of such a cross can easily be analyzed to predict the genotype of the test organism.
Here, a pea plant with red flowers (R) is test-crossed with a homozygous recessive parent (rr) and half of the resulting progeny possess red flowers while the other half contain white flowers (r).
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