Monohybrid Cross Problem Set

Problem 7: The test cross

To identify the genotype of yellow-seeded pea plants as either homozygous dominant (YY) or heterozygous (Yy), you could do a test cross with plants of genotype _______.


Test cross with yy
Although the unknown genotype could also be determined by a cross with a known heterozygote, test crosses are done with homozygous recessive individuals. If the unknown is heterozygous, the recessive trait will be present in half of the offspring.

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