Describe how a one-celled zygote develops into a baby with 5 trillion specialized cells via the processes of duplication, division, and differentiation.

Cell is the structural and functional unit of life. According to the cell theory, all cells come from existing cells. In case of humans, the fusion between a sperm cell and an egg cell form an embryo that is single celled structure. The embryo then duplicates, divides and differentiate to form a baby. Thus is the characteristic feature of an embryonic cell. An embryonic stem cell is a totipotent cell, a cell that can give rise to almost all types of cells.

An embryonic cell divides to form two cells and redivides to form four cells and continue to divide and form a spherical ball like structure known as morula. Then a cavity is formed within this structure and now known as blastocyst. It contains embryonic stem cells that differentiate to form different types of cells. After differentiation of cells, different types of cells are produce that redivide and form specific tissues and organs. In this way a baby is formed that contains 5 trillion specialized cells. 

Ihaven't done that yet, so no idea,but this is not the right place to ask