Unattached earlobes (EE or Ee)are dominant over attached earlobes (ee).A couple both have unattached earlobes.Both notice that one of their parents on both sides have attached earlobes (ee).Therefore,they correctly assume that they are carriers for attached earlobes (Ee).If the couple proceeds to have four children,then
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 dominant, and one homozygous recessive is a likely outcome, but all heterozygous, or two, three or all four homozygous is also possible.

Question

Quizplus · Accepted Answer

The chance of any one child possessing a particular phenotype does not depend on the genotype of any sibling. The parents still have the same genotype and the eggs and sperm are created from germ cells which contain both allele choices that the parents have. Therefore, the probablitiy is the same for each child to have any one particular genotype. In this case the probabilities would be 75% chance of unattached earlobes and a 25% chance of attached earlobes.Bloom's

Unattached Earlobes (EE or Ee)are Dominant Over Attached Earlobes (Ee)