You have just graduated from college as a business major, but have a special interest in genetics, ever since taking introductory biology with the new Life curriculum. Therefore, you decide to manage a pet store where you can dabble in animal breeding experiments. Your first investigation is with one of your childhood favorites, the guinea pig. When you cross a black guinea pig with a white

Question

guinea pig, three of the offspring are black and three are white. When you cross two of the black offspring you get six black and two white offspring. Which phenotype is most likely dominant? How do you know? What are the genotypes of the original parental guinea pigs?

What will be an ideal response?

Answer 1

Black is dominant because when two black guinea pigs were crossed both white and black offspring were born. Therefore black is dominant and white is recessive. The phenotypes of the original parents: Black = Bb White = bb. The original parents had equal white and black offspring therefore black = Bb and white is bb.