Suppose that, in humans, ability to roll the tongue (R) is dominant to being unable to roll (r), and having freckles (F) is dominant to having no freckles (f). If a woman heterozygous for both traits married a man with no freckles who couldn't roll his tongue, what is the probability that they would have a freckled, tongue-rolling child?
A)9/16
B)3/16
C)1/16
D)3/4
E)1/4

Question

Quizplus · Accepted Answer

The woman's genotype is RrFf, and the man's genotype is rrff. To have a child with both freckles and the ability to roll their tongue (R_F_), the child must inherit an R from the mother (a 1/2 chance) and an F from the mother (also a 1/2 chance), while the alleles from the father (r and f) are given. Multiplying these probabilities gives 1/2 * 1/2 = 1/4.

Suppose That, in Humans, Ability to Roll the Tongue (R)