The genotype of an organism that expresses a dominant trait can be determined by
A) crossing the organism with a homozygous recessive organism.
B) crossing the organism with a heterozygous dominant organism.
C) crossing the organism with a homozygous dominant organism.
D) observing the phenotype of the progeny from any cross.
E) observing the genotype of the progeny from any cross.

Question

Quizplus · Accepted Answer

Crossing an organism that expresses a dominant trait with a homozygous recessive organism (a test cross) can reveal whether the dominant trait organism is homozygous or heterozygous based on the phenotypes of the offspring. If any offspring express the recessive trait, the parent must be heterozygous.

The Genotype of an Organism That Expresses a Dominant Trait