Question

If a litter from a test cross (a crossing with a homozygous recessive, in this case, a fawn pug), produced a litter of 12 fawn puglets and 13 black puglets; what is Bobo Fett's (a black pug) genotype?

Answer 1

If Bobo Fett were a homozygous dominant (GG), crossing him with a homozygous recessive (gg) would have produced only heterozygous offspring (Gg), making all the puglets black.

On the other hand, if Bobo Fett is heterozygous (Gg), then the crossing with a homozygous recessive (gg) can produce black heterozygous puglets (Gg), and fawn puglets, that are homozygous recessive.

Given that the litter has both colors of puglets, Bobo Fett is heterozygous.