In a species of guinea pig sold as pets in some countries, there
is a common fur color known as bronze, in which the hair is
brown. A breeder has four animals: a bronze male, a bronze
female, a white male, and a white female. (The sex of the
animals is not relevant to the solution.) The breeder made
the following crosses with the outcomes shown.
Cross:
Outcome:
bronze female X bronze male
all bronze
bronze female X white
male
all white
white female X bronze
male
4 white and 5 bronze
Which phenotype is dominant?
What are the genotypes of each of the 4 parents?
If the white female and the white male were mated to each
other, what fraction of the offspring is expected to have white
hair?
Even for experts, the sex of guinea pigs is very difficult to
determine, but the breeder wants to keep the males and females
separate as much as possible. When the mating in part c. is
performed, a litter of five animals is born. What is the
probability that at least one of the five is a female? (hint:
calculating all the ways there could be 1, 2, or more females is
much harder than calculating the probability of the only situation
that would be ok for the breeder).