Nutrients and oxygen are transferred from a mother to her developing fetus through what?

Placenta

Explanation:

Placenta is the connection between the mother and developing foetus. It secretes hCG hormone. The developing foetus gets nourishment from the mother's body by placenta.

It is a temporary endocrine gland and cut after the child birth. This supplies blood, oxygen to the embryo by the process of diffusion. Placenta also acts as the excretory organ for the developing foetus.

Placenta are formed from the finger like projection of blastocyst called trophoblast.  The one trophoblast forms placenta while others helps in holing the foetus in the mother's womb.

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion