1. The cell
Unicellular & Multicellular Organism
All living organisms are made up of one or more cells. On the basis of cell number, organism are grouped into 2 categories -
Unicellular organisms :
Organism in which a single cell make the whole body. For example, Amoeba, Paramecium, bacteria & Chlamydomonas.
Multicellular organism :
Organism in which body contains more than one cell. For example - Plante, animals & fungi.