Suppose that in humans the ability to roll the tongue (R) is dominant to being unable to roll it (r). Having freckles (F) is dominant to having no freckles (f). A freckled tongue-roller could have which genotypes? (select all that apply)
A. RrFf
B. rrff
C. rrFF
D. rrFf
E. Rrff

A. RrFf

Explanation:

Given,

Ability to roll the tongue (R) is dominant over inability to roll it (r)

Freckles (F) is dominant to no freckles (f)

A freckled tongue-roller has dominant version of both the traits. So the traits will be visible even in the presence of only one dominant allele.

Thus, possible genotypes for a freckled tongue-roller will be :

RRFF

RRFf

RrFF

RrFf

Out of the give options only option A is the answer.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

answer: dna

because all cells have genes