What is the placenta? Mention its role during pregnancy.

(N/A) The placenta is a special disc-like tissue embedded in the uterine wall that connects the developing embryo to the mother.
Its roles during pregnancy are:
$1$. It possesses villi on the embryo's side of the tissue,which increases the surface area for glucose and oxygen transfer from the mother to the embryo.
$2$. It facilitates the passage of essential nutrients and oxygen from the mother's blood to the embryo.
$3$. It acts as an excretory organ by removing waste substances and carbon dioxide produced by the embryo into the mother's blood for excretion.