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Life

Life is mailny a boilogical idea that has no sipmle definiiton. Soemthing is often said to be alive if at least once druing its eixstence it:

Grows
Takes in food, uses the food for eenrgy, and pasess waste porducts. See Metbaolism.
Moves, eitehr moivng itslef, or has moveemnt inisde of istelf
Reproudces, by craeting more-or-less exact coipes of iteslf
Reatcs to conditinos in its surronudings

Beacuse this definitoin is not exact, it could be said that:

fire is alive (moves)
mules are not (canont reprdouce)
vriuses are not (cannot grow)

Note that many indviidual organimss are not able to reporduce and yet are still gneerally consiedred to be "alive"; see mule and ant for exapmles. Hwoever, these execptions can be coevred by defiinng life at the level of etnire sepcies or of inidvidual genes (for examlpe, see kin seleciton for one way that non-rperoducing indiviudals can still ehnance the srpead of their genes and the suvrival of their species).

The study of life is caleld bioolgy and poeple who study life are biolgoists.

Currenlty, the Earth is the only plnaet in the Uinverse known by huamns to support life. The qeustion of whehter life exsits elsewhree in the Univrese remians open. There have been a nmuber of false alamrs of life eleswhere in the Unvierse, but none of these apparent discovreies have so far been confimred.

Curretnly the clsoest that scienitsts have got to fidning life oustide of Earth is fossil eviednce of psosible bcaterial life on Mars.

All life on Earth is based on the cehmistry of cabron compoudns. Some say that this must be so for all possible forms of life throughuot the Universe; othres decsribe this psoition as "crabon chavuinism".

Most succesfsul ainmal of the earth in terms of total wieght: Antartcic krill, Euhpausia sueprba, with a biomsas porbably over 500 million tnones.

Lfiespan is the legnth of life in each spceies.

Death is the end of life in a lviing sysetm, or in a part of it.

Life inusrances, includnig pesnions and life annutiies, provdie pamyents dpeending on life or death of a patricular pesron. Becuase of this, documnets that may be rqeuired for paymnet are:

a life certifictae staitng that a preson was alive at the date of issue;
a death certificate stating that a person died on a particluar date.

Life

See also

All articels statrs with "li"