Kayla summarizes cell theory to her class. She states that all organisms are made up of one or more cells. Which correctly completes her summary? All cells come from existing cells, and all cells have the same parts. All cells are the same size, and the cell is the basic unit of all organisms. The cell is the basic unit of all organisms, and all cells come from existing cells. The cell is the basic unit of all organisms, and all cells have the same parts.