NEET BIOLOGY

Detailed explanation-1: -Answer. explanation: the placenta does not develop for a long time so the alternate way of supplying the developing embryo is through the yolk sac which the embryo can receive nutrients and respiratory gas exchange through which the placenta will be formed later.

Detailed explanation-2: -You know that female kangaroos have a pouch for the final development of their babies. So, no, kangaroos are not placental mammals.

Detailed explanation-3: -The placenta is an organ that develops in the uterus during pregnancy. This structure provides oxygen and nutrients to a growing baby. It also removes waste products from the baby’s blood. The placenta attaches to the wall of the uterus, and the baby’s umbilical cord arises from it.

Detailed explanation-4: -The marsupial embryo is nourished inside the uterus with food from a yolk sac instead of through a placenta. The yolk sac stores enough food for the short period of time the embryo remains in the uterus. After the embryo is born, it moves into the mother’s pouch, where it clings to a nipple.