Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies.

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. 


These results indicate which of the following? 

A) Brown is dominant to black.
B) Black is dominant to brown and to yellow.
C) Yellow is dominant to black.
D) There is incomplete dominance.
E) Epistasis is involved.


Answer: E


How many genes must be responsible for these coat colors in Labrador retrievers? A) 1 

B) 2
C) 3
D) 4
E) 5


Answer: B

In one type cross of black × black, the results were as follows:
9/16 black
4/16 yellow
3/16 brown 

The genotype aabb must result in which of the following?
A) black
B) brown
C) yellow
D) a lethal result
E) white

Answer: C


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