Question

A test cross was performed on a pea plant to determine its genotype. The offspring from the test cross were 50 percent green, round seeds and 50 percent green, wrinkled seeds, What is the genotype of the pea plant in question?​

Answer 1

Answer: The pea plant is heterozygous.

Explanation:

Since a test cross is performed on a subject that's displaying a dominant trait, you must cross it with a subject that has two recessive alleles. If all of the offspring are the same, then the genotype of the parent is two dominant alleles, because when doing a test cross, you'd have one dominant and one recessive allele for each offspring.

When you have a parent that is heterozygous, their dominant allele will pair with each recessive allele of the homozygous recessive plant and then the recessive allele of the parent will pair with each recessive allele of the homozygous recessive plant, thus giving you a 50/50 or 1:1 ratio. So if the genotype was signified as G, the pea plant would have the genotype Gg.