Question

Suppose that prior to implantation, Janetha's fertilized egg divides into two cells, and these cells then split entirely. If Janetha's pregnancy results in a healthy birth, you would know that she would have:

a) twins with identical genetic characteristics
b) a girl and a boy
c) a girl
d) a boy

Answer 1

Janetha would have twins with identical genetic characteristics, known as monozygotic or identical twins, resulting from a single zygote that has split.

Step-by-step explanation:

If Janetha's fertilized egg divides into two cells and these cells then split entirely, leading to a healthy birth, it is most likely that Janetha would have twins with identical genetic characteristics. This scenario describes the formation of monozygotic or identical twins. Unlike dizygotic or fraternal twins, which are the result of two separate eggs being fertilized by two separate sperm, monozygotic twins come from a single zygote that has split. Therefore, since they originate from the same sperm and egg combination, the twins will share the exact same genetic material. Moreover, depending on when the split occurs, they may either have individual placentas or share a placenta and a chorionic cavity, but their genetic makeup will be identical either way.