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

Question

Quizplus · Accepted Answer

Crossing the organism with a homozygous recessive organism will allow for determination of the genotype of the organism expressing the dominant trait. If the progeny all exhibit the dominant trait, then the organism being tested must be heterozygous (since one parent was homozygous recessive). If some progeny exhibit the recessive trait, then the organism being tested must be homozygous dominant.

The Genotype of an Organism That Expresses a Dominant Trait