Solutions For An Introduction to Genetic Analysis Chapter 3 Problem 6P

The origin of the chromosomes colored dark blue is the B allele of the parent. This parent has homozygous dominant genotype. The origin of the chromosomes colored light blue is the b allele of the other parent. This parent is homozygous recessive for the alleles it carries.

The very light blue color does not come from either parent but comes from the test cross done. This testcross was done by crossing a fully recessive organism with the F1 progeny.