Organism

In biology, an organism is an individual living system (such as animal, plant, fungus or micro-organism). In at least some form, all organisms are capable of reacting to stimuli, reproduction, growth and maintenance as a stable whole (after FA An organism may be unicellular or made up, as in humans, of many billions of cells grouped into specialized tissues and organs. The phrase complex organism describes any organism with more than one cell.
The term "organism" first appeared in the English language in 1701 and took on its current definition by 1834 (Oxford English Dictionary).
Based on cell type, organisms may be divided into the prokaryotic and eukaryotic groups. The prokaryotes are generally considered to represent two separate domains, called the Bacteria and Archaea, which are not closer to one another than to the eukaryotes. Eukaryotic organisms, with a membrane-bounded cell nucleus, also contain organelles, namely mitochondria and (in plants) plastids, generally considered to be derived from endosymbiotic bacteria.A similar symbiogenesis hypothesis has been proposed involving the origins of the cell nucleus, it is described as viral eukaryogenesis. Fungi, animals and plants are examples of species that are eukaryotes.