Cell theory is the scientific theory that shows us the properties of cells. Many different people contributed to cell theory. First, Hooke called the boxes he saw under magnification, "cells". Then, Schleiden concluded that plants have cells, and Schwann concluded that animals have cells. Finally, Virchow hypothesized that cells form into new cells.
Unicellular and Multicellular Organisms
In a unicellular organism, it only has one cell that carries out all the life processes. In a multicellular organism, it has numerous cells that are all different and do different functions for the organism.