1. The agouti locus in mice has three alleles: a is recessive and confers a black coat, A is dominant to a and confers an agouti coat, and A^Y is dominant to both and confers a yellow coat. A^Y is also a recessive lethal.  In addition, the independently assorting c allele is recessive (to C) and prevents the mice from making any fur pigments at all, resulting in albinos.  Two mice are crossed, and produce offspring in a ratio of 3 albino : 2 yellow : 1 black. What are the genotypes and phenotypes of the parent mice?    

2.  In cats, the X-linked allele O converts the black pigment found in the fur into an orange pigment. Heterozygous females are mosaics of orange and black pigmented fur.  The autosomal dominant allele Wprevents the deposition of any pigment at all in the fur.  A white female cat is mated to a male of unknown phenotype, and the progeny consist of 3/8 white females, 1/16 mosaic females, 1/16 orange females, 3/8 white males, 1/16 orange males, and 1/16 black males.  What are the genotypes of the parents?

3. In sweet peas the synthesis of purple anthocyanin pigment in the petals is controlled by two genes, B andD. The pathway is:

                  white intermediate —-(gene B enzyme)—>     blue intermediate —-(gene D enzyme)—>   anthocyanin (purple)           

Two plants are crossed: One is genotype BB dd, the other is bb DD (think about their phenotypes).

a) what color(s) are the F1 plants, and in what ratios?

c) If the F1 plants are self-crossed, what color(s) do you expect in the F2, and in what ratios?