Science Help: biotic/abiotic

[Mama_Rana]

I recently downloaded the free life science curriculum from Mr. Q. I'm going to start the first lesson today on biotic and abiotic. But I'm confused. At one point, I swear he says that anything that was EVER alive is considered biotic. But in another place he uses a pencil as an example of an abiotic object. But TO ME, a pencil is made of wood which comes from a tree that was once living, so wouldn't that make it biotic by his first definition?

 

I just want to clarify before I go teaching my son the wrong thing!

 

Thanks!

[flyingiguana]

http://wiki.answers.com/Q/What_are_biotic_and_abiotic_factors

 

From this site:

"A biotic factor is a living thing in an ecosystem. Even if that animal dies it is still a biotic factor because it was once living at some point. "

 

But I don't know that this site is the authority (just the first one google ran into).

 

Still, sometimes these sorts of terms get used a bit loosely.

[Mama_Rana]

Thanks, FlyingIguana.

:bigear:

Anyone else?

[ColoradoMom]

Yes, I can see your confusion. Typically abiotic factors are things like sunlight and temperature. I think it is an error.

[simka2]

But I can also see were a "pen" is abiotic, and so would be a pencil. Plus some pencils are mechanical ;)

[Mrs Mungo]

A tree would be biotic, whether or not it is currently alive. A *pencil* is not a tree, it has been transformed. Only part of the pencil was ever alive, part of it was never alive. The "pencil" in pencil form was never alive.

[Mama_Rana]

A tree would be biotic, whether or not it is currently alive. A *pencil* is not a tree, it has been transformed. Only part of the pencil was ever alive, part of it was never alive. The "pencil" in pencil form was never alive.

 

Ok, that makes sense to me. I guess the question then becomes how much "processing" renders a biotic object into an abiotic one.

For example, coal is made from a natural process that transforms organic matter using high pressure, or something like that, right? But the coal itself was never living though millions of years ago it was once organic matter, no?

 

And how about parts of organisms, like chicken bones? A bone itself is not an organism, and doesn't pass many of the tests for being a biotic object, but it was once PART of a biotic object. And my son asked about the eggs we bought at the grocery store.

 

Ack!! I obviously don't have a grasp on this myself.

[ColoradoMom]

No, I don't think that is the point of differentiating between abiotic and biotic. These terms refer to the ecosystem - specifically the biosphere. The abiotic elements of the bisopshere are mostly climate related - things such as temperature, humidity, sunlight, salinity, water, wind, rocks and soil, and periodic disturbances such as fires, hurricanes, tornadoes, and volcanic eruptions.

 

It also includes the breakdown of organic matter - which is actually a link between the two terms because decomposers break down organic matter - so that matter is food (biotic) but the end result is that the biotic factors such as amino acids and lipids, are reduced down to their individual abiotic components such as carbon, hydrogen, phosphorus, nitrogen etc.

 

I agree that there is a gray area, but pencil? No. That is not part of the ecosystem unless it is lying on the ground being decomposed by bacteria, and then it is biotic until it reaches such a stage as to be in its individual components, and then those elements would be abiotic. Perhaps the graphite inside the pencil is purely abiotic, but why use such a convoluted example?

 

The terms really don't pertain to processing of natural materials into "goods" they are specific for ecology.

 

I can see your confusion with Mr. Q's curriculum - he does state that all living or deceased organisms are biotic. Which is true. But then he goes on to describe abiotic as all non-living objects in the world - which directly contradicts what he just said because he included deceased in his definition.

 

I'd chalk it up as a "lost in translation" misunderstanding and just move on.