In dogs brown fur color B is dominant to white b A cross is

In dogs, brown fur color (B) is dominant to white (b). A cross is made between two heterozygotes. If a litter contains six pups, what is the probability that half of them will be white? Show your calculations.

Solution

If a cross is made between two heterozygotes i.e Bb X Bb the resultant punnet square should be

B

b

B

BB

Bb

b

Bb

bb

Where BB; Bb will result in puppy with brown fur and thus have probability 3/4 where as bb will result in white puppy with probability of 1/4.

In this case, the probability of passing each gene from parents is 25%, hence the probability of getting three brown and three white puppies should be 50%.