Extra Credit: Doggies Genotype

Genetics of the colors of the labs:

(B is black, bb is brown)

(ee is yellow)

Yellow= eebb and eeB_

Brown= E_bb

Black= E_B_

Mother= Yellow

Puppies the mother had:

5/12 brown

7/12 black

Mother must be: Bbee

She is yellow so she has ee, and she had black puppies so she must have one B and she had brown puppies so she must have one b.

Father must be: EEbb

If he had Ee or ee, then one of their puppies would have been yellow. Because the puppies are brown and black he must be EE. 

In order to have a brown puppy, he would need a bb. He has a bb because the mother could give a big B and have a puppy that is black. Big B is dominant over little b.