Question

A test cross is used to determine if the genotype of a plant with the dominant phenotype is homozygous or heterozygous. If the unknown is homozygous, all of the offspring of the test cross have the __________ phenotype. If the unknown is heterozygous, half of the offspring will have the __________ phenotype.

• A. Dominant, incompletely dominant
• B. Recessive, dominant
• C. Codominant, complimentary
• D. Dominant, recessive

Answer 1

The correct option is D Dominant, recessive

In a test cross:
1. The organism with the dominant trait is always crossed with an organism with the recessive trait.
2. If any offspring show the recessive trait, the unknown genotype is heterozygous.
3. If all the offspring have the dominant trait, the unknown genotype is homozygous dominant.