Question

a black guinea pig crossed with an albino guinea pig produces 12 black offspring. when the albino is crossed with a second black one,7 blacks and 5albino are obtained. what is the best explanation for this genetic situation? write genotypes for the parents, gametes, and offspring.

Answer 1

Look at the first mating - one black parent and one white parent.

Because both of these parents will pass some of their genes on their offspring, the offspring will get one allele (copy of the colour gene) from each parent. So by looking at the appearance of the offspring, you can tell what the relationship is between the two different colour alleles? Is black dominant to white? Or is white dominant to black?

Because all the offspring are black - even though they have a white allele from the white parent - you know that the black allele must be dominant to the white allele.

Which is a good start on the problem..