Question

analyze the table below and answer the question that follows.
r
r
r
rr
rr
r
rr
rr
if the ability to roll ones tongue is dominant (r) and the inability to roll ones tongue is recessive (r), what would the genotype be for someone who can not roll their tongue?
a. rr and rr
b. rr
c. rr and rr
d. rr

Explanation:

In genetics, a recessive trait (like inability to roll tongue) is only expressed when an individual has two recessive alleles. The dominant allele (R) masks the recessive allele (r). So, for the inability to roll the tongue (recessive trait), the genotype must be 'rr' as having even one 'R' (like in 'Rr' or 'RR') would result in the dominant trait (ability to roll tongue) being expressed.

Answer:

D. rr