Answer to Question #286818 in Genetics for bella

Question

Two black guinea pigs were mated and over several

years produced 29 black and 9 white offspring.Explain these results, giving the genotypes of parents

and progeny.

Answer 1

That’s not possible. Female Guinea Pigs can’t breed and safely give birth past about age 2.

Are you asking about genetics in general?

If the creatures were black and produced 25% white offspring, you can assume the parents carry the same genotype: Bb ww. Using a grid to make all the possible matches, you would have 25% of the black ones breed true to black (BB) and 25% breed white (ww). The other 50% will be black because Black is a dominant gene for the phenotype, but those offspring will carry a white recessive genotype, like the parents.

Parents that are BB bb cannot produce white offspring. Parents that are Bb ww can have offspring with Bb ww, BB bb, ww ww. The black phenotype could conceal a ww white recessive that would show up in about a quarter of the progeny.