<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> In biology, an organism (from Greek: ὀργανισμός, organismos) is any individual entity that exhibits the properties of life . It is a synonym for "life form". </P> <P> Organisms are classified by taxonomy into specified groups such as the multicellular animals, plants, and fungi; or unicellular microorganisms such as a protists, bacteria, and archaea . All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli . Humans are multicellular animals composed of many trillions of cells which differentiate during development into specialized tissues and organs . </P> <P> An organism may be either a prokaryote or a eukaryote . Prokaryotes are represented by two separate domains--bacteria and archaea . Eukaryotic organisms are characterized by the presence of a membrane - bound cell nucleus and contain additional membrane - bound compartments called organelles (such as mitochondria in animals and plants and plastids in plants and algae, all generally considered to be derived from endosymbiotic bacteria). Fungi, animals and plants are examples of kingdoms of organisms within the eukaryotes . </P>

What is the main function of an organism