Solution:

The colour of a dog’s coat is determined by a set of genes. There are at least eleven known sequence series that determine a dog’s colour (A, B, C, D, E, F, G, M, P, S, T). Each of a dog’s parents gives it one copy. A dog in the B series, for example, is genetically black or brown. Assume one parent is homozygous black (BB) while the other is homozygous brown (BB) (bb).

All of the progeny will be heterozygous in this situation (Bb).

Because black (B) is the prevailing colour, all of the progeny will be black. They will, however, carry both B and b alleles. If these heterozygous pups are crossed, 25 homozygous blacks (BB), 15 heterozygous blacks (Bb), and 25 homozygous browns (bb) will result.