: In some breeds of dogs, black (B) is the result of the production of black eumelanin ( a fur pigment protein) and it is dominant over brown (b) or the production of brown eumelanin. If we cross a true breeding male black dog with a female brown dog, what are the phenotypes and genotypes of the F1 and F2? In order to solve the problem, follow the steps below while answering the questions.

Gentoype of F1: all Bb

Phenotype of F1: black

Genotypes and phenotypes of F2:

1/4 BB - black fur

1/2 Bb - black fur

1/4 bb - brown fur

Explanation:

Black fur (B) is dominant over brown fur (b).

A true breeding black dog will have the genotype BB.

A true breeding brown dog will have the genotype bb.

If both of them are crossed:

BB   x   bb

F1 progeny: All Bb with Black fur.

At F2:

Bb   x   Bb

Progeny:

1 BB - black fur

2 Bb - black fur

1 bb - brown fur

Hence:

Gentoype of F1 = all Bb

Phenotype of F1 = black

Genotypes and phenotypes of F2:

1 BB - black fur

2 Bb - black fur

1 bb - brown fur

answer: dna

because all cells have genes