Suppose a male mouse is Bb and a female is bb. What percent of the mice offspring from these two mice would you expect to have black fur?

1 Answer | Add Yours

sciftw's profile pic

sciftw | High School Teacher | (Level 1) Educator Emeritus

Posted on


The question does not state which gene is dominant, so I do not know if B is black or b is black.  That does not matter though based on the parental genotypes that the question uses.  I will assume that BB and Bb are phenotypically black, and bb is phenotypically white.  

The initial cross is between a black (Bb) mouse and a white (bb) mouse.    

The genes will sort independently, so the black individual can donate B or b. The white individual can only donate b. 

Two potential offspring will be genotypically Bb.  Two potential offspring will be bb.  50% show the dominant trait, and 50% show the recessive trait.  That is why it does not matter if black is dominant or recessive.  Half of the F1 generation could be black, and half could be white. 


We’ve answered 319,642 questions. We can answer yours, too.

Ask a question