Dihybrid Cross Problem Set

Problem 12: What is the genotype of the agouti parent?

Two unlinked loci effect mouse hair color. CC or Cc mice are agouti. Mice with genotype cc are albino because all pigment production and deposition of pigment in hair is blocked. At the second locus, the B allele (black agouti coat) is dominant to the b allele (brown agouti coat). A mouse with a black agouti coat is mated with an albino mouse of genotype bbcc. Half of the offspring are albino, one quarter are black agouti, and one quarter are brown agouti. What is the genotype of the black agouti parent?

B. BbCc
This is the only possibility for this combination of offspring.
C. bbCC
E. BBcc

The Biology Project
University of Arizona
September 9, 1998
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