what is the definition of life? I am not asking for the meaning, just the definition

[lepidoptera]

Any ideas?

[Ophiolite]

Q: what is the definition of life?

A: Hotly debated.

[Ophiolite]

Since no one seems to want to address your query seriously (probably because people have run out of ways to say 'Have you googled it?') here is a half ways decent one:

“Living organisms are autopoietic systems: self-constructing, self-maintaining, energy-transducing autocatalytic entities” in which information needed to construct the next generation of organisms is stabilized in nucleic acids that replicate within the context of whole cells and work with other developmental resources during the life-cycles of organisms, but they are also “systems capable of evolving by variation and natural selection: self-reproducing entities, whose forms and functions are adapted to their environment and reflect the composition and history of an ecosystem”

from http://plato.stanford.edu/entries/life/

[the tree]

Life generaly covers anything that will do all of the following:

• grow
  
• move
  
• reproduce
  
• consume
  
• die
  

[blike]

True, but fire could be said to do the same. It's hard to find a perfect definition, but the one Ophiolite is really good.

[Dak]

Life generaly covers anything that will do all of the following:

• grow
  
• move
  
• reproduce
  
• consume
  
• die
  

as well as fire, vaccuoles (little sacks of phospholipids) also adsorb new phospholipids (consume), which causes them to grow and, when they reach a certain size, they split in two (ie reproduce). they also float about so i suppose could be said to move.

 

as for die, this cant be used in the definition of life, as for somethin too die it must have been defined as being alive in the first place (otherwize it doesnt die, it ceases operating/breaks etc)

 

opholites answre is good, unless your taliking about the possiblity of life on another planet -- opholites answre would have to be reworded in that case, as it is too terra-centric (eg, replace the reference to nucleic acids with a reference to the need for a way of storing and passing on the hereditary information etc)

[Ollie]

In the UK, the answer to that question, as taught up to A-level (I don't know what they say there, or even if they ask the question, as I didn't take it) is generally something along the lines of the GRIMREF, MR GREEN or MRS GREN acronymns. Using GRIMREF, all living things should:

 

Grow

Reproduce

Irritate (have senses)

Move

Respire

Excrete

Food (eat)

 

That's probably not a conclusive list, but it's a fairly good starting point.

[YT2095]

yeah, the ability to "Sense" is critical to segregate it from such things as fire.

 

although it`s still somewhat debatable as to what constitutes "sensing"

[AtomicMX]

hmmm i would like sayonara to answer this one.

[j_p]

Move?

 

Respire?

 

I'd be startled if my rhubard decided to visit the herb garden.

Or if it started releasing carbon dioxide.

 

I thought both were characteristic of animals?

[Ollie]

Respiration doesnt have to result in oxygen, and in fact many plants reverse photosynthesis and burn oxygen while producing CO2 at night. And plants can move too. The french for sunflower is (I believe) tournasol as they will move their heads to follow the sun through the day.

[j_p]

Respiration doesnt have to result in oxygen, ... they will move their heads to follow the sun through the day.

I thought that in both common and scientific usage respiration is defined as the exchange of carbon dioxide for oxygen, not the exchange of one gas for another.

 

It that movement, or growth? When my plants lean into the sun, it is caused by greater growth on the shaded side; and growth is listed separately from movement.

 

And even if the sunflower has movement other than growth [such as the cells being swollen with water? how does the sunflower work?], my rhubarb does not.

 

But, even if you are correct and "many plants ... burn oxygen while producing CO2" and the sunflower moves it's flower, there are plants that do not.

[Ollie]

I thought that in both common and scientific usage respiration is defined as the exchange of carbon dioxide for oxygen, not the exchange of one gas for another.

 

No, commonly people say "respiration" when they mean "breathing" but respiration is the process by which an organism obtains energy.

 

It that movement, or growth? When my plants lean into the sun, it is caused by greater growth on the shaded side; and growth is listed separately from movement.

 

Sunflowers can't grow that fast, though I'm not sure of the mechanism by which they turn, but there are other example. Venus fly traps snap shut when triggered, some trees will turn leaves to avoid/follow direct sunlight. Some curl up when touched, or even approached.

 

And even if the sunflower has movement other than growth [such as the cells being swollen with water? how does the sunflower work?]' date=' my rhubarb does not.

 

But, even if you are correct and "many plants ... burn oxygen while producing CO2" and the sunflower moves it's flower, there are plants that do not.[/quote']

 

Well, there are people that do not reproduce. Are they any less alive?

[ecoli]

Sunflowers can't grow that fast' date=' though I'm not sure of the mechanism by which they turn, [/quote']

 

Suflowers and all flowers, for that matter, use growth to "turn". Whereever the sun is at certain location, the side that's away from the sun grows more then the side that is away from it. As a result the plant curves towards the sun. So, plants "turning" should be considered more growth then movement.

[j_p]

No' date=' commonly people say "respiration" when they mean "breathing" but respiration is the process by which an organism obtains energy.

 

Sunflowers can't grow that fast, though I'm not sure of the mechanism by which they turn, but there are other example. Venus fly traps snap shut when triggered, some trees will turn leaves to avoid/follow direct sunlight. Some curl up when touched, or even approached.

[/quote']

I am fairly certain the mechanism in Flytraps and those leaves that fold together when they are touched is rapid change in water levels.

 

But that doesn't address my original point; many plants can not move, so how can movement as an activity separate from growth be considered a defining characteristic of life?

Well, there are people that do not reproduce. Are they any less alive?

 

Humans, in general, can reproduce; so the definition would apply to species rather than to individuals?

[Mokele]

I am fairly certain the mechanism in Flytraps and those leaves that fold together when they are touched is rapid change in water levels.

 

Nope, it's actually sudden growth/expansion, which utilizes change in water levels somehow (I dunno, I just grow em, I don't sutdy them). It was actually only just figured out recently. Each time the trap opens and closes, the cells get bigger.

 

Mokele

[j_p]

[Howl of frustration]

 

Can you find a slightly more detailed explanation? I have always been fascinated by this.

[lepidoptera]

Okay. You all have been describing life, not life What I mean is what is the definition of life, not living matter.

[Mokele]

Can you find a slightly more detailed explanation? I have always been fascinated by this.

 

Google it

[j_p]

Google it

Still looking, and I have found no mention of growth in the closure motion.

 

I have found the Nature article which attributes the rapidity to mechanical factors.

 

But I haven't read all 70,000 links yet; I'll keep you informed.

[Ophiolite]

Okay. You all have been describing life, not life[/i'] What I mean is what is the definition of life, not living matter.

Please tell us how life differs from living matter.

[Yumeji]

I'd define life as the time frame for which something is in existance. Assuming you're not looking for the characteristics that describe living organisms.

[abbadon]

Since no one seems to want to address your query seriously (probably because people have run out of ways to say 'Have you googled it?') here is a half ways decent one:

“Living organisms are autopoietic systems: self-constructing' date=' self-maintaining, energy-transducing autocatalytic entities” in which information needed to construct the next generation of organisms is stabilized in nucleic acids that replicate within the context of whole cells and work with other developmental resources during the life-cycles of organisms, but they are also “systems capable of evolving by variation and natural selection: self-reproducing entities, whose forms and functions are adapted to their environment and reflect the composition and history of an ecosystem” [/i']

from http://plato.stanford.edu/entries/life/

 

few words: immanence of being!

[Ophiolite]

A plausible spiritual definition.