Which of the following is a function of the placenta? Check all that apply.
A. Allows the building blocks of proteins to diffuse from maternal to fetal blood
B. To prevent gestational diabetes, the placenta blocks glucose from passing from the fetus to the mother
C. Helps the fetus dispose of metabolic waste that would normally be excreted by its own kidneys
D. Allows for gas exchange
E. Transfers stem cells from the mother's bone marrow to the fetal tissue