Question

A human embryo doesn't need the kind of yolk that is present in a chick embryo. Explain.

Answer 1

The yolk of an egg is the food and nutrient source for the chick as it grows, humans do not need this because they get all of the nutrients they need for development from the mother through the umbilical cord. 

Answer 2

Answer:

The egg yolk of a chicken corresponds to the female's oocyte II, which would become a chick if fertilized by a male gamete. The yolk have the nutrients that provide the energy for embryo development. In the case of humans and other animals called eutheries or placentals, embryos are fed through an organ called placenta, which connects the embryonic organism with mother's organism. Thus, there is no need for a type of "yolk" to provide the embryo with energy, as is the case with chickens and other animal species in which embryonic development occurs without direct attachment to the maternal organism.