Question

the ability to roll the tongue in humans is coded by the dominant allele r. the inability to roll the tongue is coded by the recessive allele r. a man with an rr allele combination for the trait produces a zygote with a woman with an rr allele combination for the trait. which allele combination could occur in the zygote?
rr
rr
rr
rrr

Explanation:

The man has \( RR \) alleles. He can only pass on \( R \) alleles. The woman has \( rr \) alleles. She can only pass on \( r \) alleles. When they combine, the zygote will have one \( R \) from the man and one \( r \) from the woman.

Answer:

A. \( Rr \)