cells
Cells are the building blocks of life. This is clear from the photo in Figure below . It shows stacks upon stacks of cells in an onion plant. Cells are also the basic functional units of living things. They are the smallest units that can carry out the biochemical reactions of life. No matter how different organisms may be from one another, they all consist of cells. Moreover, all cells have the same basic parts and processes. Knowing about cells and how they function is necessary to understanding life itself.