Cells are the basic structural and functional unit of life.
Cells differ in shape and size. These differences may be with in an organism and also from organism to organism.
Size and shape of a cell is determined by the specialized function it performs.
The number of cells in an organism decides its size. Greater the number, larger will be the size of the organism.
Basically, a cell has three major parts - Cell membrane, Nucleus and Cytoplasm.
Plant cells differ from animal cells in having plastids, cell wall, larger vacuoles and in not having centrioles.