Explain why an egg is so much larger than a sperm cell.

Egg is larger as it must carry not just the genetic material but also immediate nutrients for development of the new developing organism.

Explanation:

immediate first few divisions must be supported by the cell itself.the nutrients can be drawn from external sources after a few cell divisions . what I mean is that proteins, carbohydrates, enzymes, all must be duplicated with the process of cell division and the cell needs resources for easy and handy replication and they must be found easily and handy and this is the function of the mother cell, here the egg pr ovum and hence bigger in size.