Question

1. Your black labrador has a genotype of BbEe. Which of the following is correct? Select all that apply.

   		your labrador could have had one yellow parent
   		if he mates with a brown labrador, and ANY of pups are yellow, it means the brown labrador genotype has to be bbEe.
   		if he mates with a yellow labrador it would be impossible to have any brown pups
   		when he mates with a bbee labrador, the pups will be 1/4 black, 1/4 brown and 1/2 yellow
   		the only way for him to father black, brown and yellow pups all in the same litter is if he mates with another BbEe  labrador .

Answer 1

Given the genotype of Black labrador is BbEe.

This genotypye is only possible if its parent had BBEE and bbee genetype or BbEe and Bbee.

We know that yellow color comes from presence of ee genes, which switch offs the B gene. Black color arises due to presence of either Bb or BB genes. bb genes gives rise to brown color.

So,

Statement 1 is correct.

Statement 2 is also correct. Because only possible genotype for brown labrador is bbEe. If we take bbee is for yellow color. The ee genes will silence the b genes giving yellow color.

Statement 3 is not correct. There are 2 possiblities of yellow labrador, Bbee or BBee. By breeding it with BbEe, we will have bbEe in progeny. So it is incorrect to say that we won't have brown pup.

Statement 4, BbEe X bbee will give BbEe, Bbee, bbEe, bbee pups

The ee will always produce yellow color. So it is correct that 1/4 will be black, 1/4 will be brown, and 1/2 will be yellow.

Statement 5, if he mates with BbEe, the pups produced will be

9 black, 4 yellow and 3 brown pups. These color pups can also be produced when he breeds with bbee labrador as discussed in statement 4. So it is incorrect.