Organism

In biology, an organism (from Greek: ὀργανισμός, organismos) is any individual entity that embodies the properties of life.

Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms, development and evolution.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

Multicellular organisms are organisms that consist of more than one cell, in contrast to unicellular organisms.

In biology, an organism (from Greek: ὀργανισμός, organismos) is any individual entity that embodies the properties of life.

One popular definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

In biology, taxonomy is the science of naming, defining (circumscribing) and classifying groups of biological organisms on the basis of shared characteristics.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells.

All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction, growth or metabolism.

Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parents".

All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli.

In biology, homeostasis is the state of steady internal physical and chemical conditions maintained by living systems.

All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli.

The ability of an organism or organ to respond to external stimuli is called sensitivity.

Humans, squids, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development.

Organs exist in most multicellular organisms.

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).

Algae (singular alga ) is an informal term for a large, diverse group of photosynthetic eukaryotic organisms that are not necessarily closely related, and is thus polyphyletic.

More than 99% of all species, amounting to over five billion species, that ever lived are estimated to be extinct.

In biology, extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species.

Estimates on the number of Earth's current species range from 2 million to 1 trillion, of which over 1.7 million have been documented.

In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.

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).

The number of mitochondria in a cell can vary widely by organism, tissue, and cell type.

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).

In biology organs are defined as confined functional units within an organism.

Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the biochemical machinery of a host cell for reproduction. Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction, growth or metabolism.

A virus is a small infectious agent that replicates only inside the living cells of an organism.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

Like all other organisms, bacteria contain ribosomes for the production of proteins, but the structure of the bacterial ribosome is different from that of eukaryotes and Archaea.

Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction, growth or metabolism.

Metabolism (, from μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.

Naturally, this rules out autonomous reproduction: they can only be passively replicated by the machinery of the host cell.

The cell (from Latin cella, meaning "small room" ) is the basic structural, functional, and biological unit of all known organisms.

The same laws that govern non-living chemistry govern the chemical processes of life.

Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms.

It is generally the phenomena of entire organisms that determine their fitness to an environment and therefore the survivability of their DNA-based genes.

Deoxyribonucleic acid (DNA) is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.

While viruses sustain no independent metabolism and thus are usually not classified as organisms, they do have their own genes, and they do evolve by mechanisms similar to the evolutionary mechanisms of organisms.

It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules.

Humans, squids, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development.

Humans are able to create new and complex ideas, and to develop technology, which is unprecedented among other organisms on Earth.

Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the biochemical machinery of a host cell for reproduction.

Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms.

Autotrophs produce usable energy (in the form of organic compounds) using light from the sun or inorganic compounds while heterotrophs take in organic compounds from the environment.

A heterotroph (Ancient Greek ἕτερος héteros = "other" plus trophe = "nutrition") is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter.