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Encyclopedia > Life
For different meanings of related words, see Lives, Live, Live!, Living, Alive.
Life

Life on a rocky peak
Scientific classification
(unranked) Life (Biota)
Domains and Kingdoms
Look up life, living in Wiktionary, the free dictionary.
Wikispecies has information related to:

Life is a condition that distinguishes organisms from inorganic objects, i.e. non-life, and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally. A physical characteristic of life is that it feeds on negative entropy.[1][2] In more detail, according to physicists such as John Bernal, Erwin Schrödinger, Wigner, and John Avery, life is a member of the class of phenomena which are open or continuous systems able to decrease their internal entropy at the expense of substances or free energy taken in from the environment and subsequently rejected in a degraded form (see: entropy and life).[3][4] Life on Earth redirects here. ... Look up Life in Wiktionary, the free dictionary. ... LiVES (LiVES is a Video Editing System) is a video editing program and VJ tool, released under GNU General Public License. ... Look up live in Wiktionary, the free dictionary. ... Live! is the name of several albums: Live! (April Wine album) Live! (Bob Marley and the Wailers album) Live! (Cherish the Ladies album) Live! (Habib Koité & Bamada album) Live! (Status Quo album) Live! (The Police album) Live! (Yoshiaki Miyanoue album) Live! (Jonathan Edwards) Live! (Voltaire album) Live! (film), 2005 Dutch... Look up living in Wiktionary, the free dictionary. ... Look up alive in Wiktionary, the free dictionary. ... Image File history File links Download high-resolution version (993x660, 365 KB) Summary Lion Rock at Piha, Waitakere Ranges (10 January 2005. ... For other uses, see Scientific classification (disambiguation). ... Empires Biota is the superdomain that categorizes life. ... Look up domain in Wiktionary, the free dictionary. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... This article is about the tv programme Life on Earth. ... A nanobe Nanobes are tiny filamental structures first found in some rocks and sediments. ... In the physical sciences, non-life is an umbrella term set to distinguish or characterize those inanimate chemical precursors found in the primeval soup of the early years of planetary evolution from which life, theoretically, evolved or came into existence. ... Non-cellular life is life that exists without cells. ... In phylogenetics, a grouping of organisms is said to be paraphyletic (Greek para = near and phyle = race) if all the members of the group have a common ancestor, but the group does not include all the descendants of the most recent common ancestor of all group members. ... In phylogenetics, a taxon is polyphyletic (Greek for of many races) if the trait its members have in common evolved separately in different places in the phylogenetic tree. ... In the physical sciences, non-life is an umbrella term set to distinguish or characterize those inanimate chemical precursors found in the primeval soup of the early years of planetary evolution from which life, theoretically, evolved or came into existence. ... Cellular life is life with cells. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... In phylogenetics, a grouping of organisms is said to be paraphyletic (Greek para = near and phyle = race) if all the members of the group have a common ancestor, but the group does not include all the descendants of the most recent common ancestor of all group members. ... Domains Domain Archaea Domain Eukaryota Neomura is the hypothetical ancestor of the two domains of Archaea and Eukaryota. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Supergroups Apusozoa Cabozoa    Rhizaria    Excavata Corticata    Archaeplastida    Chromalveolata A Bikont is a eukaryotic cell with two flagella, developed by a unique pathway. ... Orders Apusomonadida Ancyromonadida Hemimastigida The Apusozoa comprise several genera of flagellate protozoa. ... A Bikont is a eukaryotic cell with two flagella. ... Phyla Cercozoa Foraminifera Radiolaria The Rhizaria are a major line of protists. ... This article is about the protist group called excavates. ... Supergroups Archaeplastida Chromalveolata Corticata is a clade suggested by Cavalier-Smith to encompass the eukaryote supergroups of Archaeplastida and Chromalveolata. ... The Archaeplastida are a major line of eukaryotes, comprising the land plants, green and red algae, and a small group called the glaucophytes. ... Red algae Classes Florideophyceae Bangiophyceae Cyanidiophyceae The red algae are a large group of mostly multicellular, marine algae, including many notable seaweeds. ... Possible classes Glaucocystis Cyanophora Gloeochaete The glaucophytes (Glaucophyta Skuja), also referred to as glaucocystophytes or glaucocystids, are a tiny group of freshwater algae. ... Divisions Green algae land plants (embryophytes) non-vascular embryophytes Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses vascular plants (tracheophytes) seedless vascular plants Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongue ferns seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta... The chromalveolates (Chromalveolata) are a hypothetical grouping of eukaryotes, comprising the Chromista and alveolates, as suggested by Tom Cavalier-Smith. ... Typical classes Colored groups Chrysophyceae (golden algae) Synurophyceae Actinochrysophyceae (axodines) Pelagophyceae Phaeothamniophyceae Bacillariophyceae (diatoms) Raphidophyceae Eustigmatophyceae Xanthophyceae (yellow-green algae) Phaeophyceae (brown algae) Colorless groups Oomycetes (water moulds) Hypochytridiomycetes Bicosoecea Labyrinthulomycetes (slime nets) Opalinea Proteromonadea The heterokonts or stramenopiles are a major line of eukaryotes. ... Orders Class Pavlovophyceae    Pavlovales Class Prymnesiophyceae    Prymnesiales    Phaeocystales    Isochrysidales    Coccolithales The haptophytes, classed either as the Prymnesiophyta or Haptophyta, are a group of algae. ... Typical genera Campylomonas Chilomonas Chroomonas Cryptomonas Falcomonas Geminigera Goniomonas Guillardia Hemiselmis Plagioselmis Proteomonas Storeatula Rhodomonas Teleaulax The cryptomonads are a small group of flagellates, most of which have chloroplasts. ... The alveolates are a major line of protists. ... Supergroups Opisthokonta Amoebozoa Unikont is a eukaryotic cell with a single flagellum, at least ancestrally. ... Subgroups Mycetozoa(slime moulds) Archamoebae    Pelobiontida    Entamoebida Gymnamoebia Various others The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means of internal cytoplasmic flow. ... Subgroups Kingdom Animalia Kingdom Fungi Choanozoa Choanoflagellates Corallochytrids Mesomycetozoea Nucleariids The opisthokonts (Greek: (opisthō-) = rear, posterior + (kontos) = pole i. ... The opisthokonts are a broad group of eukaryotes, including both the animals and fungi, together with a few sorts of protists. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Phyla Subkingdom Parazoa Porifera (sponges) Subkingdom Agnotozoa Placozoa Orthonectida Rhombozoa Subkingdom Metazoa Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented... Green people redirects here. ... Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Image File history File links Wikispecies-logo. ... Wikispecies is a wiki-based online project supported by the Wikimedia Foundation that aims to create a comprehensive free content catalogue of all species (including animalia, plantae, fungi, bacteria, archaea, and protista). ... In biology and ecology, an organism (in Greek organon = instrument) is a living being. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... In the physical sciences, non-life is an umbrella term set to distinguish or characterize those inanimate chemical precursors found in the primeval soup of the early years of planetary evolution from which life, theoretically, evolved or came into existence. ... For other uses, see Death (disambiguation), Dead (disambiguation), or Death (band). ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... For other uses, see Reproduction (disambiguation) Reproduction is the biological process by which new individual organisms are produced. ... For other uses, see Adaptation (disambiguation). ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... Wikipedia does not have an article with this exact name. ... John Desmond Bernal (May 10, 1901—September 15, 1971) was an Irish-born scientist (from Nenagh, County Tipperary), known for pioneering X-ray crystallography. ... Schrödinger in 1933, when he was awarded the Nobel Prize in Physics Bust of Schrödinger, in the courtyard arcade of the main building, University of Vienna, Austria. ... See e. ... John Scales Avery, born in 1933 in Lebanon to American parents, is a theoretical chemist noted for his research publications in bioenergetics, thermodynamics, and quantum chemistry. ... For other uses, see: information entropy (in information theory) and entropy (disambiguation). ... The thermodynamic free energy is a measure of the amount of mechanical (or other) work that can be extracted from a system, and is helpful in engineering applications. ... Over the last century, much writing and research has been devoted to the relationship between the thermodynamic quantity entropy and the evolution of life. ...


A diverse array of living organisms can be found in the biosphere on Earth. Properties common to these organisms—plants, animals, fungi, protists, archaea and bacteria—are a carbon- and water-based cellular form with complex organization and heritable genetic information. They undergo metabolism, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. For other uses, see Biosphere (disambiguation). ... For other uses, see Plant (disambiguation). ... For other uses, see Animal (disambiguation). ... For the fictional character, see Fungus the Bogeyman. ... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Carbon forms the backbone of biology for all life on Earth. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... For other uses, see Organization (disambiguation). ... For other uses, see Gene (disambiguation). ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... A stimulus is the following: In physiology, a stimulus (physiology) is something external that elicits or influences a physiological or psychological activity or response. ... Reproduction is the creation of one thing as a copy of, product of, or replacement for a similar thing, e. ... For other uses, see Natural selection (disambiguation). ...


An entity with the above properties is considered to be a living organism, that is an organism that is alive hence can be called a life form. However, not every definition of life considers all of these properties to be essential. For example, the capacity for descent with modification is often taken as the only essential property of life. This definition notably includes viruses, which do not qualify under narrower definitions as they are acellular and do not metabolise. Broader definitions of life may also include theoretical non-carbon-based life and other alternative biology. Some forms of artificial life, however, especially wet artificial life, might alternatively be classified as real life. Life on Earth redirects here. ... This article is about biological infectious particles. ... Non-cellular life is life that exists without cells. ... Alternative biochemistry is the speculative biochemistry of alien life forms that differ radically from those on Earth. ... Alternative biology refers to the study of theoretical or non-traditional life forms such as acellular life, non-carbon-based life, extraterrestrial life, cyborg life or artificial life. ... This article is about a field of research. ... Wet artificial life or wet alife refers to research efforts to safely synthesize self-sustaining new cellular life forms from abiotic components such as pure chemical substances. ...

Contents

Definitions

There is no universal definition of life; there are a variety of definitions proposed by different scientists. To define life in unequivocal terms is still a challenge for scientists[5][6].


Conventional definition: Often scientists say that life is a characteristic of organisms that exhibit the following phenomena:

  1. Homeostasis: Regulation of the internal environment to maintain a constant state; for example, sweating to reduce temperature.
  2. Organization: Being composed of one or more cells, which are the basic units of life.
  3. Metabolism: Consumption of energy by converting nonliving material into cellular components (anabolism) and decomposing organic matter (catabolism). Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life.
  4. Growth: Maintenance of a higher rate of synthesis than catalysis. A growing organism increases in size in all of its parts, rather than simply accumulating matter. The particular species begins to multiply and expand as the evolution continues to flourish.
  5. Adaptation: The ability to change over a period of time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism's heredity as well as the composition of metabolized substances, and external factors present.
  6. Response to stimuli: A response can take many forms, from the contraction of a unicellular organism when touched to complex reactions involving all the senses of higher animals. A response is often expressed by motion, for example, the leaves of a plant turning toward the sun or an animal chasing its prey.
  7. Reproduction: The ability to produce new organisms. Reproduction can be the division of one cell to form two new cells. Usually the term is applied to the production of a new individual (either asexually, from a single parent organism, or sexually, from at least two differing parent organisms), although strictly speaking it also describes the production of new cells in the process of growth.
  8. Controversial: The unknowing state on weither or not a being "lives" depending on it's mental, and physical state. More so in nature, the physical presence of a thing is enough to classify life; a plant has no mental abilities (no brain, or soul), which sparks conversation on its actual state of life. A human being- one named Shannon Dillon, for instance- is alive and is an example of life for her mental, and physical capabilities.
Plant life.
Plant life.
Herds of zebra and impala gathering on the Masai Mara plain
Herds of zebra and impala gathering on the Masai Mara plain
Marine life around a coral reef.

However, others cite several limitations of this definition[7]. Thus, many members of several species do not reproduce, possibly because they belong to specialized sterile castes (such as ant workers), these are still considered forms of life. One could say that the property of life is inherited; hence, sterile or hybrid organisms such as mules, ligers, and eunuchs are alive although they are not capable of self-reproduction. However, (a) The species as a whole does reproduce, (b) There are no cases of species where 100% of the individuals reproduce, and (c) specialized non-reproducing individuals of the species may still partially propagate their DNA or other master pattern through mechanisms such as kin selection. Homeostasis is the property of either an open system or a closed system, especially a living organism, which regulates its internal environment so as to maintain a stable, constant condition. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Anabolism is the metabolic process that builds larger molecules from smaller ones. ... Anabolism is the aspect of metabolism that contributes to growth. ... The term cell growth is used in two different ways in biology. ... This article is about evolution in biology. ... See Heredity (disambiguation) for other meanings. ... It has been suggested that Parthenogenesis be merged into this article or section. ... Sexual reproduction is a union that results in increasing genetic diversity of the offspring. ... A controversy is a contentious dispute, a disagreement over which parties are actively arguing. ... Image File history File linksMetadata Download high-resolution version (1424x1072, 672 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Life Hoh Rain Forest User:Goldom/gallery Metadata This file contains additional information, probably added from the digital... Image File history File linksMetadata Download high-resolution version (1424x1072, 672 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Life Hoh Rain Forest User:Goldom/gallery Metadata This file contains additional information, probably added from the digital... For other uses, see Plant (disambiguation). ... Image File history File links Size of this preview: 800 × 518 pixelsFull resolution‎ (966 × 626 pixels, file size: 184 KB, MIME type: image/jpeg) Cropped and straighten version of http://commons. ... Image File history File links Size of this preview: 800 × 518 pixelsFull resolution‎ (966 × 626 pixels, file size: 184 KB, MIME type: image/jpeg) Cropped and straighten version of http://commons. ... This article does not cite any references or sources. ... Image File history File linksMetadata Download high resolution version (3000x2001, 4710 KB) Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high resolution version (3000x2001, 4710 KB) Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Some of the biodiversity of a coral reef, in this case the Great Barrier Reef, Australia. ... For other uses, see Mule (disambiguation). ... For other uses, see Liger (disambiguation). ... European illustration of a Eunuch (1749) Chief Eunuch of Ottoman Sultan Abdul Hamid II at the Imperial Palace, 1912. ... In evolutionary biology, kin selection refers to changes in gene frequency across generations that are driven at least in part by interactions between related individuals, and this forms much of the conceptual basis of the theory of social evolution. ...


Viruses and aberrant prion proteins are often considered replicators rather than forms of life, a distinction warranted because they cannot reproduce without very specialized substrates such as host cells or proteins, respectively. Also, the Rickettsia and Chlamydia are examples of bacteria that cannot independently fulfill many vital biochemical processes, and depend on entry, growth, and replication within the cytoplasm of eukaryotic host cells. However, most forms of life rely on foods produced by other species, or at least the specific chemistry of Earth's environment. A prion (IPA: [1] ) — short for proteinaceous infectious particle (-on by analogy to virion) — is a type of infectious agent composed only of protein. ... Species Rickettsia felis Rickettsia prowazekii Rickettsia rickettsii Rickettsia typhi Rickettsia conorii Rickettsia africae etc. ... Chlamydia is a common term for Chlamydiae. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Cross section of cell with cytoplasm labeled at center right. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ...


Still others contest such definitions of life on philosophical grounds. They offer the following as examples of life: viruses which reproduce; storms or flames which "burn"; certain computer software programs which are programmed to mutate and evolve; future software programs which may evince (even high-order) behavior; machines which can move; and some forms of proto-life consisting of metabolizing cells without the ability to reproduce.[citation needed] Still, most scientists would not call such phenomena expressive of life. Generally all seven characteristics are required for a population to be considered a life form.


The systemic definition of life is that living things are self-organizing and autopoietic (self-producing). These objects are not to be confused with dissipative structures (e.g. fire). Systems theory is an interdisciplinary field of science. ... Look up Autopoiesis in Wiktionary, the free dictionary. ... A dissipative system (or dissipative structure) is an open system which is operating far from thermodynamic equilibrium within an environment that exchanges energy, matter or entropy. ...


Variations of this definition include Stuart Kauffman's definition of life as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle. Stuart Alan Kauffman (born September 28, 1939) is a theoretical biologist and complex systems researcher, who has given much thought to the origin of life on Earth. ... An autonomous agent is a system situated in, and part of, an environment, which senses that environment, and acts on it, over time, in pursuit of its own agenda. ... A multi-agent system (MAS) is a system composed of several software agents, collectively capable of reaching goals that are difficult to achieve by an individual agent or monolithic system. ... A thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. ...


Proposed definitions of life include:

  1. Living things are systems that tend to respond to changes in their environment, and inside themselves, in such a way as to promote their own continuation.[citation needed]
  2. Life is a characteristic of self-organizing, self-recycling systems consisting of populations of replicators that are capable of mutation, around most of which homeostatic, metabolizing organisms evolve.

The above definition includes worker caste ants, viruses and mules while precluding flames. It also explains why bees can be alive and yet commit suicide in defending their hive. They are only individual instances of the living system that comprises all life forms on planet Earth (which is the only living system known to mankind). Look up Characteristic in Wiktionary, the free dictionary. ... Self-organization refers to a process in which the internal organization of a system, normally an open system, increases automatically without being guided or managed by an outside source. ... For other uses, see System (disambiguation). ... In a generic sense, a replicator can be anything capable of self-replication. ... For linguistic mutation, see Apophony. ... Homeostasis or homoeostasis is the property of an open system, especially living organisms, to regulate its internal environment so as to maintain a stable condition, by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... Meat Eater ant colony swarming Fire ants Eusociality is the phenomenon of reproductive specialization found in some animals. ... Wikipedia does not yet have an article with this exact name. ... Stop editing pages god ... In its common modern meaning, a mule is the offspring of a male donkey and a female horse. ... Flame generated by the burning of a candle. ... For other uses, see Western honey bee and Bee (disambiguation). ... Hive may refer to: Hive mind, one of several forms of collective consciousness The Hives, a rock band Hive (record producer), a producer in the drum and bass music genre Hive (game) is an abstract-strategy board game published in 2001 Hive Records, a record label HIVE (ISP), the smallest... This article is about Earth as a planet. ... Look up Mankind in Wiktionary, the free dictionary. ...

  1. Type of organization of matter producing various interacting forms of variable complexity, whose main property is to replicate almost perfectly by using matter and energy available in their environment to which they may adapt. In this definition "almost perfectly" relates to mutations happening during replication of organisms that may have adaptive benefits.
  2. Life is a potentially self-perpetuating open system of linked organic reactions, catalyzed simultaneously and almost isothermally by complex chemicals (enzymes) that are themselves produced by the open system.

Origin of life

Main article: Origin of life

Although it cannot be pinpointed exactly, evidence suggests that life on Earth has existed for about 3.7 billion years [8]. For the definition, see Life. ... Image File history File links Aerial view of Grand Prismatic Spring, Yellowstone National Park Image by NPS Photo - http://www. ... Image File history File links Aerial view of Grand Prismatic Spring, Yellowstone National Park Image by NPS Photo - http://www. ... Grand Prismatic Spring. ... Yellowstone redirects here. ... This article is about the tv programme Life on Earth. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ...


There is no truly "standard" model for the origin of life, but most currently accepted scientific models build in one way or another on the following discoveries, which are listed roughly in order of postulated emergence:

  1. Plausible pre-biotic conditions result in the creation of the basic small molecules of life. This was demonstrated in the Miller-Urey experiment, and in the work of Sidney Fox.
  2. Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane.
  3. Procedures for producing random RNA molecules can produce ribozymes, which are able to produce more of themselves under very specific conditions.

There are many different hypotheses regarding the path that might have been taken from simple organic molecules to protocells and metabolism. Many models fall into the "genes-first" category or the "metabolism-first" category, but a recent trend is the emergence of hybrid models that do not fit into either of these categories.[9] The experiment The Miller-Urey experiment (or Urey-Miller experiment) was an experiment that simulated hypothetical conditions present on the early Earth and tested for the occurrence of chemical evolution. ... Sidney W. Fox (24 March 1912 - 10 August 1998) was a Los Angeles-born biochemist. ... Phospholipid Two schematic representations of a phospholipid. ... This fluid lipid bilayer cross section is made up entirely of phosphatidylcholine. ... Look up cell membrane in Wiktionary, the free dictionary. ... Left: An RNA strand, with its nitrogenous bases. ... // A ribozyme (from ribonucleic acid enzyme, also called RNA enzyme or catalytic RNA) is an RNA molecule that catalyzes a chemical reaction. ... An organic compound is any of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... For other uses, see Gene (disambiguation). ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ...


Extraterrestrial life

Main articles: Extraterrestrial life, Astrobiology

Earth is the only planet in the universe known to harbour life. The Drake equation has been used to estimate the probability of life elsewhere, but scientists disagree on many of the values of variables in this equation (although strictly speaking Drake equation estimates relate the number of extraterrestrial civilizations in our galaxy with which we might come in contact - not probability of life elsewhere). Depending on those values, the equation may either suggest that life arises frequently or infrequently. Drake himself estimated the number of civilizations in our galaxy with which we might expect to be able to communicate at any given time as equal to one. Green people redirects here. ... The DNA structure might not be the only nucleic acid in the universe capable of supporting life[1] Astrobiology (from Greek: ἀστρο, astro, constellation; βίος, bios, life; and λόγος, logos, knowledge) is the interdisciplinary study of life in space, combining aspects of astronomy, biology and geology. ... This article is about Earth as a planet. ... For other uses, see Universe (disambiguation). ... The Drake equation (rarely also called the Green Bank equation or the Sagan equation) is a famous result in the speculative fields of exobiology, astrosociobiology and the search for extraterrestrial intelligence. ...


Relating to the origin of life on Earth, panspermia and exogenesis are theories proposing that life originated elsewhere in the universe and was subsequently transferred to Earth perhaps via meteorites, comets or cosmic dust. However those theories do not help explain the origin of this extraterrestrial life. Panspermia is a proven process (based on the principles of Biology, Microbiology, Physics, Chemistry, Astronomy, and assumption that life existed already in the universe) that explains how all life in the universe and/or solar system comes from a seed of life. ... Willamette Meteorite A meteorite is a natural object originating in outer space that survives an impact with the Earths surface without being destroyed. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... “Space dust” redirects here. ...


Classification of life

Species Genus Family Order Class Phylum Kingdom Domain Life
The hierarchy of biological classification's major eight levels. Life is divided into domains, which are subdivided into further groups. Intermediate minor rankings are not shown.

Traditionally, people have divided organisms into the classes of plants and animals, based mainly on their ability of movement. The first known attempt to classify organisms, as per personal observations, was conducted by the Greek philosopher Aristotle. For other uses, see Scientific classification (disambiguation). ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... u fuck in ua ... The word Animals when used alone has several possible meanings in the English language. ... For other uses, see Aristotle (disambiguation). ...


He classified all living organisms known at that time as either a plant or an animal. Aristotle distinguished animals with blood from animals without blood (or at least without red blood), which can be compared with the concepts of vertebrates and invertebrates respectively. He divided the blooded animals into five groups: viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes and whales. The bloodless animals were also divided into five groups: cephalopods, crustaceans, insects (which also included the spiders, scorpions, and centipedes, in addition to what we now define as insects), shelled animals (such as most molluscs and echinoderms) and "zoophytes". Though Aristotle's work in zoology was not without errors, it was the grandest biological synthesis of the time, and remained the ultimate authority for many centuries after his death. His observations on the anatomy of octopus, cuttlefish, crustaceans, and many other marine invertebrates are remarkably accurate, and could only have been made from first-hand experience with dissection. [10] This article does not cite any references or sources. ... Invertebrate is an English word that describes any animal without a spinal column. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... For other uses, see Bird (disambiguation). ... Reptilia redirects here. ... For other uses, see Amphibian (disambiguation). ... For other uses, see Fish (disambiguation). ... Suborders Mysticeti Odontoceti Archaeoceti (extinct) (see text for families) The order Cetacea (IPA: , L. cetus, whale) includes whales, dolphins and porpoises. ... Orders Subclass Nautiloidea †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida †Orthocerida †Ascocerida †Bactritida Subclass †Ammonoidea †Goniatitida †Ceratitida †Ammonitida Subclass Coleoidea †Belemnoidea †Aulacocerida †Belemnitida †Hematitida †Phragmoteuthida Neocoleoidea (most living cephalopods) ?†Boletzkyida Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida The cephalopods (Greek plural (kephalópoda); head-foot) are the mollusc class... For the Dutch band, see Crustacean (band). ... For other uses, see Spider (disambiguation). ... Superfamilies Pseudochactoidea Buthoidea Chaeriloidea Chactoidea Iuroidea Scorpionoidea See classification for families. ... For other uses, see Centipede (disambiguation). ... Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Classes Subphylum Homalozoa Gill & Caster, 1960 Class Homostelea Class Homoiostelea Class Stylophora Gill & Caster, 1960 Class Ctenocystoidea Robison & Sprinkle, 1969 Subphylum Crinozoa Class Eocrinoidea Jaekel, 1899 Class Paracrinoidea Regnéll, 1945 Class Cystoidea von Buch, 1846 Class Blastoidea Class Crinoidea Subphylum Asterozoa Class Ophiuroidea Class Asteroidea Subphylum Echinozoa Helicoplacoidea †  ?Arkarua... Zoophyte - mistake of nature. ...


The exploration of parts of the New World produced large numbers of new plants and animals that needed descriptions and classification. The old systems made it difficult to study and locate all these new specimens within a collection and often the same plants or animals were given different names because the number of specimens were too large to memorize. A system was needed that could group these specimens together so they could be found, the binomial system was developed based on morphology with groups having similar appearances. In the latter part of the 16th century and the beginning of the 17th, careful study of animals commenced, which, directed first to familiar kinds, was gradually extended until it formed a sufficient body of knowledge to serve as an anatomical basis for classification. Frontispiece of Peter Martyr dAnghieras De orbe novo (On the New World). Carte dAmérique, Guillaume Delisle, 1722. ... The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ...


Carolus Linnaeus is best known for his introduction of the method still used to formulate the scientific name of every species. Before Linnaeus, long many-worded names (composed of a generic name and a differentia specifica) had been used, but as these names gave a description of the species, they were not fixed. In his Philosophia Botanica (1751) Linnaeus took every effort to improve the composition and reduce the length of the many-worded names by abolishing unnecessary rhetorics, introducing new descriptive terms and defining their meaning with an unprecedented precision. In the late 1740s Linnaeus began to use a parallel system of naming species with nomina trivialia. Nomen triviale, a trivial name, was a single- or two-word epithet placed on the margin of the page next to the many-worded "scientific" name. The only rules Linnaeus applied to them was that the trivial names should be short, unique within a given genus, and that they should not be changed. Linnaeus consistently applied nomina trivialia to the species of plants in Species Plantarum (1st edn. 1753) and to the species of animals in the 10th edition of Systema Naturae (1758). By consistently using these specific epithets, Linnaeus separated nomenclature from taxonomy. Even though the parallel use of nomina trivialia and many-worded descriptive names continued until late in the eighteenth century, it was gradually replaced by the practice of using shorter proper names combined of the generic name and the trivial name of the species. In the nineteenth century, this new practice was codified in the first Rules and Laws of Nomenclature, and the 1st edn. of Species Plantarum and the 10th edn. of Systema Naturae were chosen as starting points for the Botanical and Zoological Nomenclature respectively. This convention for naming species is referred to as binomial nomenclature. Today, nomenclature is regulated by Nomenclature Codes, which allows names divided into ranks; separately for botany and for zoology. Whereas Linnaeus classified for ease of identification, it is now generally accepted that classification should reflect the Darwinian principle of common descent. Carl Linnaeus, Latinized as Carolus Linnaeus, also known after his ennoblement as  , (May 13, 1707[1] – January 10, 1778), was a Swedish botanist, physician and zoologist[2] who laid the foundations for the modern scheme of nomenclature. ... In biology, binomial nomenclature is a standard convention used for naming species. ... Writing the Species Plantarum was one of Carolus Linnaeus two great contributions to the Scientific community. ... Cover of the tenth edition of Linnaeuss Systema Naturae (1758). ... Nomenclature refers to a method of assigning (unique) names. ... For the science of classifying living things, see alpha taxonomy. ... Writing the Species Plantarum was one of Carolus Linnaeus two great contributions to the Scientific community. ... Cover of the tenth edition of Linnaeuss Systema Naturae (1758). ... The International Code of Botanical Nomenclature (ICBN) is the set of rules that governs plant nomenclature, i. ... The International Code of Zoological Nomenclature (ICZN) is a set of rules in zoology that have one fundamental aim: to provide the maximum universality and continuity in classifying all animals according to taxonomic judgment. ... This article does not cite any references or sources. ... The Nomenclature Codes (or the Codes of nomenclature) are the rulebooks that govern biological nomenclature. ... In botanical nomenclature, a taxon is usually assigned to a rank in a hierarchy. ... In zoology, a taxon is usually assigned to a rank in a hierarchy. ... A group of organisms is said to have common descent if they have a common ancestor. ...


The Fungi have long been a problematic group in the biological classification: Originally, they were treated as plants. For a short period Linnaeus had placed them in the taxon Vermes in Animalia because he was misinformed: the hyphae were said to have been worms. He later placed them back in Plantae. Copeland classified the Fungi in his Protoctista, thus partially avoiding the problem but acknowledging their special status. The problem was eventually solved by Whittaker, when he gave them their own kingdom in his five-kingdom system. As it turned out, the fungi are more closely related to animals than to plants. Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Vermes (worms) is an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals. ... Hyphae of Penicillium A hypha (plural hyphae) is a long, branching filamentous cell of a fungus, and also of unrelated Actinobacteria. ... For other uses, see Worm (disambiguation). ... Herbert Faulkner Copeland (1902-1968) was an American biologist who contributed to the theory of biological kingdoms. ... Robert Whittaker (1920-1980) was an American vegetation ecologist, active in the 1950s through the 1970s. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ...


As new discoveries enabled us to study cells and microorganisms, new groups of life where revealed, and the fields of cell biology and microbiology were created. These new organisms were originally described separately in Protozoa as animals and Protophyta/Thallophyta as plants, but were united by Haeckel in his kingdom Protista, later the group of prokaryotes were split of in the kingdom Monera, eventually this kingdom would be divided in two separate groups, the Bacteria and the Archaea, leading to the six-kingdom system and eventually to the three-domain system. The 'remaining' protists would later be divided into smaller groups in clades in relation to more complex organisms. Thomas Cavalier-Smith, who has published extensively on the classification of protists, has recently proposed that the Neomura, the clade which groups together the Archaea and Eukarya, would have evolved from Bacteria, more precisely from Actinobacteria. Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... A cluster of Escherichia coli bacteria magnified 10,000 times. ... Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, container) is an academic discipline that studies cells. ... An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... Leishmania donovani, (a species of protozoan) in a bone marrow cell (in Greek proto = first and zoa = animals) are one-celled eukaryotes (that is, unicellular microbes whose cells have membrane-bound nuclei) that commonly show characteristics usually associated with animals, mobility and heterotrophy. ... Plants that do not have well-differenciatedbody desighn fall in this group. ... Ernst Haeckel. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... Prokaryotic bacteria cell structure Prokaryotes (IPA: //) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles. ... Figure 1. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... The three-domain system is a biological classification introduced by Carl Woese in 1990 that emphasizes his separation of prokaryotes into two groups, originally called Eubacteria and Archaebacteria. ... Thomas Cavalier-Smith is a professor of evolutionary biology at the University of Oxford, and is winner of the International Prize for Biology 2004 and one of the most notable researchers concerning the relationships, development, and classification of living things. ... Domains Domain Archaea Domain Eukaryota Neomura is the hypothetical ancestor of the two domains of Archaea and Eukaryota. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Subclasses Acidimicrobidae Actinobacteridae Coriobacteridae Rubrobacteridae Sphaerobacteridae The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria. ...


As microbiology, molecular biology and virology developed, non-cellular reproducing agents were discovered, sometimes these are considered to be alive and are treated in the domain of non-cellular life named Acytota or Aphanobionta. An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... Molecular biology is the study of biology at a molecular level. ... Virology, often considered a part of microbiology or of pathology, is the study of organic viruses: their structure and classification, their ways to infect and exploit cells to reproduce and cause disease, the techniques to isolate and culture them, and their potential uses in research and therapy. ... Non-cellular life is life that exists without cells. ...


And thus all the primary taxonomical ranks were established: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species For the science of classifying living things, see alpha taxonomy. ... Look up rank in Wiktionary, the free dictionary. ... In biology, a domain (also superregnum, superkingdom, or empire) is the top-level grouping of organisms in scientific classification, higher than a kingdom. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... In biological taxonomy, a phylum (Greek plural: phyla) is a taxon in the rank below kingdom and above class. ... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ... In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... The hierarchy of scientific classification In biological classification, family (Latin: familia, plural familiae) is a rank, or a taxon in that rank. ... For other uses, see Genus (disambiguation). ... For other uses, see Species (disambiguation). ...


Since the 1960s a trend called cladistics has emerged, arranging taxa in an evolutionary or phylogenetic tree. If a taxon includes all the descendants of some ancestral form, it is called monophyletic, as opposed to paraphyletic, groups based on traits which have evolved separately and where the most recent common ancestor is not included are called polyphyletic. It has been suggested that Clade be merged into this article or section. ... Fig. ... A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ... In phylogenetics, a group is monophyletic (Greek: of one race) if it consists of an inferred common ancestor and all its descendants. ... In phylogenetics, a grouping of organisms is said to be paraphyletic (Greek para = near and phyle = race) if all the members of the group have a common ancestor, but the group does not include all the descendants of the most recent common ancestor of all group members. ... The most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. ... In phylogenetics, a taxon is polyphyletic (Greek for of many races) if the trait its members have in common evolved separately in different places in the phylogenetic tree. ...


A new formal code of nomenclature, the PhyloCode, to be renamed "International Code of Phylogenetic Nomenclature" (ICPN), is currently under development, intended to deal with clades, which do not have set ranks, unlike conventional Linnaean taxonomy. It is unclear, should this be implemented, how the different codes will coexist. Types of Clade (Note: Stem-based is now branch-based, to avoid confusion with the term stem group which means total clade minus crown clade.) The PhyloCode is a developing draft for a formal set of rules governing phylogenetic nomenclature. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... Title page of Systema Naturae, 10th edition, 1758. ...

Linnaeus
1735
2 kingdoms
Haeckel
1866[11]
3 kingdoms
Chatton
1937[12]
2 empires
Copeland
1956[13]
4 kingdoms
Whittaker
1969[14]
5 kingdoms
Woese et al.
1977[15]
6 kingdoms
Woese et al.
1990[16]
3 domains
(not treated) Protista Prokaryota Monera Monera Eubacteria Bacteria
Archaebacteria Archaea
Eukaryota Protista Protista Protista Eukarya
Vegetabilia Plantae Fungi Fungi
Plantae Plantae Plantae
Animalia Animalia Animalia Animalia Animalia

Carl Linnaeus, Latinized as Carolus Linnaeus, also known after his ennoblement as  , (May 13, 1707[1] – January 10, 1778), was a Swedish botanist, physician and zoologist[2] who laid the foundations for the modern scheme of nomenclature. ... Ernst Haeckel. ... The two-empire system is the top-level biologicial classification system in general use before the establishment of the three-domain system. ... Herbert Faulkner Copeland (1902-1968) was an American biologist who contributed to the theory of biological kingdoms. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... Robert Whittaker (1920-1980) was an American vegetation ecologist, active in the 1950s through the 1970s. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... Carl Richard Woese (born July 15, 1928, Syracuse, New York) is an American microbiologist famous for defining the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese and which is now standard practice. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... The three-domain system is a biological classification introduced by Carl Woese in 1990 that emphasizes his separation of prokaryotes into two groups, originally called Eubacteria and Archaebacteria. ... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... Prokaryotes are unicellular (in rare cases, multicellular) organisms without a nucleus. ... Figure 1. ... Figure 1. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Divisions Green algae land plants (embryophytes) non-vascular embryophytes Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses vascular plants (tracheophytes) seedless vascular plants Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongue ferns seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta... For other uses, see Plant (disambiguation). ... For the fictional character, see Fungus the Bogeyman. ... For the fictional character, see Fungus the Bogeyman. ... For other uses, see Plant (disambiguation). ... For other uses, see Plant (disambiguation). ... For other uses, see Plant (disambiguation). ... For other uses, see Animal (disambiguation). ... For other uses, see Animal (disambiguation). ... For other uses, see Animal (disambiguation). ... For other uses, see Animal (disambiguation). ... For other uses, see Animal (disambiguation). ...

See also

For the song by Girls Aloud see Biology (song) Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, speech lit. ... Over the last century, much writing and research has been devoted to the relationship between the thermodynamic quantity entropy and the evolution of life. ... This article is about a field of research. ... Synthetic life and artificial life (not to be confused with the field of Artificial Life) are terms used to refer to manufactured, synthesized or created life forms. ... Green people redirects here. ... Cellular life is life with cells. ... Non-cellular life is life that exists without cells. ... Organic life Organic life is life which is cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, reproduce and—through natural selection—adapt. ... Carbon forms the backbone of biology for all life on Earth. ... A cellular automaton (plural: cellular automata) is a discrete model studied in computability theory, mathematics, and theoretical biology. ... Life on Earth redirects here. ... An extremophile is an organism, usually unicellular, which thrives in or requires extreme conditions that would exceed optimal conditions for growth and reproduction in the majority of mesophilic terrestrial organisms. ... Hydrothermal vents are fissures in a planets surface from which geothermally heated water issues. ... In biological taxonomy, a kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. ... For the definition, see Life. ... Prehistoric life is a term used to refer to diverse organisms that inhabited Earth from the origin of life about 3. ... For other uses, see Death (disambiguation), Dead (disambiguation), or Death (band). ... In the physical sciences, non-life is an umbrella term set to distinguish or characterize those inanimate chemical precursors found in the primeval soup of the early years of planetary evolution from which life, theoretically, evolved or came into existence. ... For other uses, see Gaia. ... Taxonomy, sometimes alpha taxonomy, is the science of finding, describing and naming organisms, thus giving rise to taxa. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... For other uses, see Species (disambiguation). ... Gospers Glider Gun creating gliders. The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. ... This article is about the physical universe. ... Personal life (or everyday life or human existence) is an individual humans personal, private career (including, but not the same as, their employment career), and is a common notion in modern existence -- although more so in more prosperous parts of the world, such as Western Europe and North America... The well-being or quality of life of a population is an important concern in economics and political science. ... Not to be confused with the Ultimate Question or Answer to Life, the Universe, and Everything in The Hitchhikers Guide to the Galaxy. ...

References

  1. ^ Schrödinger, Erwin (1944). What is Life?. Cambridge University Press. ISBN 0-521-42708-8. 
  2. ^ Margulis, Lynn; Sagan, Dorion (1995). What is Life?. University of California Press. ISBN 0-520-22021-8. 
  3. ^ Lovelock, James (2000). Gaia – a New Look at Life on Earth. Oxford University Press. ISBN 0-19-286218-9. 
  4. ^ Avery, John (2003). Information Theory and Evolution. World Scientific. ISBN 9812383999. 
  5. ^ http://www.astrobio.net/news/article226
  6. ^ http://www.nbi.dk/~emmeche/cePubl/97e.defLife.v3f.html
  7. ^ http://forums.hypography.com/biology/6702-what-exactly-constitutes-life.html
  8. ^ http://www.ucmp.berkeley.edu/exhibits/historyoflife.php
  9. ^ http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&id=doi:10.1098/rsif.2005.0045
  10. ^ http://www.ucmp.berkeley.edu/history/aristotle.html, references for this site are located here

Further reading

  • Kauffman, Stuart. The Adjacent Possible: A Talk with Stuart Kauffman. Retrieved Nov. 30, 2003 from [1]
  • Walker, Martin G. LIFE! Why We Exist...And What We Must Do to Survive ([2] Wiki Book Page) ([3] Web Site), Dog Ear Publishing, 2006, ISBN 1-59858-243-7

External links

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COMMENTARY     

Georgi+Gladyshev
1st February 2012
Thermodynamics optimizes the physiology of life
Thermodynamics serves as a basis for optimal solutions of the tasks of physiology, which are solved by organisms in the characteristic process of life: evolution, development, homeostasis, and adaptation. It is stated that the quasiequilibrium thermodynamics of quasiclosed complex systems serves as an impetus of evolution, functions, and activities of all levels of biological systems’ organization. This fact predetermines the use of Gibbs’ methods and leads to a hierarchical thermodynamics in all spheres of physiology. The interaction of structurally related levels and sub-levels of biological systems is determined by the thermodynamic principle of substance stability. Thus, life is accompanied by a thermodynamic optimization of physiological functions of biological systems. Living matter, while functioning and evolving, seeks the minimum of specific Gibbs free energy of structure formation at all levels. The spontaneous search of this minimum takes place with participation of not only spontaneous, but also non-spontaneous processes, initiated by the surrounding environment. The hormone optimization of the treatment of various pathologies, presented by Dr. Sergey A. Dzugan et al. demonstrates the effectiveness of their innovative medical approach.
“Hierarchical thermodynamics in accordance with the laws of nature creates and optimizes forms and functions of living systems in their habitat. This optimization is connected with the search of minimums of specific Gibbs free energy formation of dynamic structures of all hierarchies.”

In the compressed general formulation, life can be defined as the phenomenon of existence of the energy-dependent dynamic hierarchic structures, as mandated by thermodynamics under certain conditions existing on celestial bodies.
http://knol.google.com/k/georgi-gladyshev/thermodynamics-optimizes-the-physiology/169m15f5ytneq/44

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