Answer:
E. Two heterozygous, one homozygous recessive and one homozygous dominant is a likely outcome, but all heterozygous, or two, three or all four homozygous are also possible.
Explanation:
The question is incomplete. It is a multiple choice question that is missing the answers:
Unattached earlobes (EE or Ee) are described in the textbook as dominant over attached earlobes (ee). A couple both have unattached earlobes. Both notice that one of their parents on both sides has attached earlobes (ee). Therefore, they correctly assume that they are carriers for attached earlobes (Ee). The couple proceeds to have four children.
A. They can be certain that three will be heterozygous and one homozygous recessive.
B. If the first three are heterozygous, the fourth must be homozygous recessive.
C. The children must repeat the grandparents' genotype (Ee).
D. All children must have unattached earlobes since both parents possess the dominant gene for it.
E. Two heterozygous, one homozygous recessive and one homozygous dominant is a likely outcome, but all heterozygous, or two, three or all four homozygous are also possible.
Solution:
Parents Ee Ee
Offspring EE Ee Ee ee
These are all possible genotypes of the offspring. Since each child has an equal change of carrying any of this genotypes, the best we can say that each of the four children or any number of children they have could carry any one of these four allele pairs
