A zebra population has a mutant allele for spots. The spot trait (T) is dominant to the striped allele. A spotted male mates with a striped female. Assuming he is homozygous, what is the probability that they will have striped offspring?

Answer: The probability of having striped offspring is zero.

Explanation: From the information provided, spotted allele (T) is dominant to striped allele (t). A homozygous spotted male will have a genotype TT, while a striped female will have a genotype tt. A cross between the two of them will produce offsprings with Tt genotype. This means that all the offsprings will be heterozygous with Tt genotype. Because T is dominant t, Tt genotype will manifest outwardly as spotted. Therefore the probability of having a striped offspring is zero.

A cross of TT x tt is shown below:

_ T T

t Tt Tt

t Tt Tt

Zero

Explanation:

The probability that they will produce a striped offspring is zero. Since being a striped organism has to be inherited in the homozygous recessive form, and with the father been homozygous for the spot trait, the mother is striped, thus she has to have the homozygous received form, putting this together can only give rise to the offspring with spot but is heterozygous for the trait.