Chapter 11, Introduction to Genetics - Assessment - 11.1 The Work of Gregor Mendel - Understand Key Concepts/Think Critically - Page 332: 5

To find out the genotype of the white ram, we would cross it with a black ram ($aa$). If the white ram were homozygous dominant, all the offspring would be heterozygous and would be white. If the white ram were heterozygous, the offspring could either be white or black (genotype $Aa$ or $aa$). The offspring could not be homozygous dominant ($AA$).

To find out the genotype of the white ram, we would cross it with a black ram ($aa$). If the white ram were homozygous dominant, all the offspring would be heterozygous and would be white. If the white ram were heterozygous, the offspring could either be white or black (genotype $Aa$ or $aa$). The offspring could not be homozygous dominant ($AA$).