Organism Organism 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". 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. An organism may be either a prokaryote or a eukaryote.
Anaerobic organism using hydrogenosomes. Some organisms metabolise primarily using glycogen, for example the Nereid (worm)s and some polychaetes, or the juvenile form of the pork parasite "Trichinella spiralis" which causes trichinosis. Anaerobic organism An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if free oxygen is present. (In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment.) An anaerobic organism may be unicellular (e.g. protozoans, bacteria) or multicellular. For practical purposes, there are three categories of anaerobe: obligate anaerobes, which are harmed by the presence