Question

In humans, the allele for attached ear lobes (e) is recessive to the allele for free ear lobes (E).

If both of Lisa's parents have attached ear lobes, then
A.
Lisa must have free ear lobes.
B.
Lisa must have her ears pierced.
C.
Lisa may have either attached ear lobes or free ear lobes.
D.
Lisa must have attached ear lobes.

Answer 1

Lisa must have attached earlobes!

Step-by-step explanation:

I did it on test

Answer 2

Attached ear lobes are recessive to free ear lobes, so an individual must be homozygous recessive (ee) in order to have attached ear lobes. Therefore, we can conclude that since both of Lisa's parents have attached ear lobes, they are both homozygous recessive (ee). In a cross between two homozygous recessive parents, all offspring will be homozygous recessive, as shown in the Punnett Square below:

e e

e ee ee

e ee ee

Since Lisa must be homozygous recessive, she must have attached ear lobes.