Chapter 12 - Patterns of Inheritance - 12.5 The Testcross: Revealing Unknown Genotypes - Data Analysis - Page 232: 1

Possible Genotype Trait A Trait B AABB 100%dominant 100%dominant AaBB 50%dominant 100%dominant AABb 100%dominant 50%dominant AaBb 50%dominant 50%dominant Getting 100% dominant is the same as breeding true.

In a test cross, 50% or 100% of progeny will show the dominant phenotype, depending on whether the unknown parent was heterozygous or homozygous dominant. To create the table in the answer, simply type out all four possible genotypes (homozygous or heterozygous for each of the two traits) and fill in the possible outcome for a testcross.