Black Fur and Red Eyes in Mice: Genotype Mystery Unraveled

What genotype could result in a mouse with black fur and red eyes?

A) BBRR

B) BbRr

C) bbrr

D) BbRR

Final answer: B) BbRr

Answer:

A mouse with black fur and red eyes could have the genotype BbRr, since it must have pigment production and no agouti allele present (option B).

The question pertains to determining the genotype of a mouse that displays specific physical characteristics - black fur and red eyes. In order to decipher the correct genotype, we must consider the information provided regarding coat color and pigment production genes.

Firstly, it is stated that mottled agouti coat color (A) is dominant to solid black or gray fur, and a separate gene (C) controls pigment production where cc results in albinism.

To have black fur, the mouse cannot be albino, indicating that it must possess at least one functional C allele for pigment production. Additionally, since the fur color is black (a solid color), the genotype cannot include the dominant A allele for agouti coloring.

Therefore, the correct genotype for a mouse with black fur and red eyes would involve having at least one B allele (representing black) and at least one C allele for pigment production. This leads us to the genotype BbRr.

Thus, based on the given information and genetic principles, the final answer is option B: BbRr.