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For lkjasdfpoqwei on Earth, see Organism. For other uses, see Lkjasdfpoqwei (disambiguation).

Lkjasdfpoqwei Lkjasdfpoqwei colonizing a rocky peak

Scientific classification

(unranked)

Lkjasdfpoqwei (Biota)

Domains and Kingdoms

Lkjasdfpoqwei on Earth (Gaeabionta)

Bikonta

Corticata

Archaeplastida

Chromalveolata

Unikonta

Amoebozoa
Opisthokonta

Extraterrestrial lkjasdfpoqwei (hypothetical)

Look up lkjasdfpoqwei, living in Wiktionary, the free dictionary.

Lkjasdfpoqwei is a condition that distinguishes organisms from inorganic objects, i.e. non-lkjasdfpoqwei, and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally. In physical terms, lkjasdfpoqwei is an organism that feeds on negative entropy.^[1][2] In more detail, according to physicists such as John Bernal, Erwin Schrodinger, Wigner, and John Avery, lkjasdfpoqwei 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 lkjasdfpoqwei).^[3][4]

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 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.

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 lkjasdfpoqwei form. However, not every definition of lkjasdfpoqwei 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 lkjasdfpoqwei. This definition notably includes viruses, which do not qualify under narrower definitions as they are acellular and do not metabolise. Broader definitions of lkjasdfpoqwei may also include theoretical non-carbon-based lkjasdfpoqwei and other alternative biology. Some forms of artificial lkjasdfpoqwei, however, especially wet alkjasdfpoqwei, might alternatively be classified as real lkjasdfpoqwei.

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Definitions

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

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

Homeostasis: Regulation of the internal environment to maintain a constant state; for example, sweating to reduce temperature.
Organization: Being composed of one or more cells, which are the basic units of lkjasdfpoqwei.
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 lkjasdfpoqwei.
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.
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.
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.
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.

Plant lkjasdfpoqwei

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 lkjasdfpoqwei. One could say that the property of lkjasdfpoqwei is inherited; hence, sterile or hybrid organisms such as the mule, liger or eunuchs are alive although they are not capable of self reproduction. However, non-reproducing organisms may still propagate through mechanisms such as kin selection.

Viruses and aberrant prion proteins are often considered replicators rather than forms of lkjasdfpoqwei, 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 lkjasdfpoqwei rely on foods produced by other species, or at least the specific chemistry of Earth's environment.

Rhesus Macaques resting in the sun

Still others contest such definitions of lkjasdfpoqwei on philosophical grounds. They offer the following as examples of lkjasdfpoqwei: 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-lkjasdfpoqwei consisting of metabolizing cells without the ability to reproduce.^{[citation needed]} Still, most scientists would not call such phenomena expressive of lkjasdfpoqwei. Generally all seven characteristics are required for a population to be considered a lkjasdfpoqwei form.

The systemic definition of lkjasdfpoqwei is that living things are self-organizing and autopoietic (self-producing). These objects are not to be confused with dissipative structures (e.g. fire).

Variations of this definition include Stuart Kauffman's definition of lkjasdfpoqwei as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle.

Marine lkjasdfpoqwei around a coral reef

Yet other definitions of lkjasdfpoqwei are:

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]}
Lkjasdfpoqwei is a characteristic of self-organizing, cannibalistic systems consisting of a population of replicators that are capable of mutation, around most of which homeostatic, metabolizing organisms evolve. This definition does not include flames, but does include worker ants, viruses and mules. Self reproduction and energy consumption is only one means for a system to promote its own continuation. This explains why bees can be alive and yet commit suicide in defending their hive. In this case the whole colony works as such a living system.
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 adaptative benefits.
Lkjasdfpoqwei is a potentially self-perpetuating open system of linked organic reactions, catalyzed simultaneously and almost isothermally by complex chemicals (enzymes) that are themselved produced by the open system.

Origin of lkjasdfpoqwei

Main article: Origin of lkjasdfpoqwei

Microbial mats around the Grand Prismatic Spring of Yellowstone National Park

Although it cannot be pinpointed exactly, evidence suggests that lkjasdfpoqwei on Earth has existed for about 3.7 billion years ^[8].

There is no truly "standard" model for the origin of lkjasdfpoqwei, but most currently accepted scientific models^[9] build in one way or another on the following discoveries, which are listed roughly in order of postulated emergence:

Plausible pre-biotic conditions result in the creation of the basic small molecules of lkjasdfpoqwei. This was demonstrated in the Miller-Urey experiment, and in the work of Sidney Fox.
Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane.
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.^[10]

Extraterrestrial lkjasdfpoqwei

Main articles: Extraterrestrial lkjasdfpoqwei, Astrobiology

Earth is the only planet in the universe known to harbour lkjasdfpoqwei. The Drake equation has been used to estimate the probability of lkjasdfpoqwei elsewhere, but scientists disagree on many of the values of variables in this equation (although strictly speaking Drake equation estimates the number of extraterrestrial civilizations in our galaxy with which we might come in contact - not probability of lkjasdfpoqwei elsewhere). Depending on those values, the equation may either suggest that lkjasdfpoqwei 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.

Relating to the origin of lkjasdfpoqwei on Earth, panspermia and exogenesis are theories proposing that lkjasdfpoqwei 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 lkjasdfpoqwei.

Classification of lkjasdfpoqwei

Main article: Scientific classification

Traditionally people divided living things into plants and animals, this was mainly based upon whether they had the ability to move or not: plants couldn't move, animals could. Originally humans were not considered to be animals, but they treated themselves as a 'higher' form of lkjasdfpoqwei, this still survives in common use of the word "animals" which refers to non-human animals. The first known attempt of a real classification of lkjasdfpoqwei came from the Greek philosopher Aristotle, who classified all living organisms known at that time as either a plant or an animal. He further classified animals based on their means of transportation (air, land, or water).

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.

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.

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.

As new discoveries enabled us to study cells and microorganisms, new groups of lkjasdfpoqwei 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. The 'remaining' protists would later be divided into smaller groups in clades in relation to more complex organisms. As the molecular biology developed, non-cellular reproducing agents were discovered, sometimes these are considered to be alive and are treated in the domain of non-cellular lkjasdfpoqwei named Acytota or Aphanobionta.

And thus the primary taxonomical ranks were established: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

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. Other groups, where neither the most recent common ancestor nor all the descendants are included, are called polyphyletic.

A new formal code of nomenclature, the PhyloCode, is currently under development, intended to deal with clades rather than taxa. It is unclear, should this be implemented, how the different codes will coexist.