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Why is carbon so important?
Carbon is the basis of all organic molecules.
It makes up our genetic material (DNA and RNA) and proteins, which are
essential for life. Carbon is so special because of its ability to
bond to almost any other molecule. The major element within our bodies
is carbon.
What is the carbon cycle?
The carbon cycle is the process through which carbon
is cycled through the air, ground, plants, animals, and fossil fuels.
Large amounts of carbon exist in the atmosphere as carbon dioxide (CO2).
Carbon dioxide is cycled by green plants during the process known as photosynthesis
to make organic molecules (glucose, which is food). This is where
the nourishment of every heterotrophic organism comes from. Animals
do the opposite of plants--they release carbon dioxide back into the air
as a waste product from respiration. (Note: Plants also undergo
respiration to make food, but the majority of the carbon dioxide in the
air comes from heterotrophic respiration). Decomposers, when they
break down dead organic matter, release carbon dioxide into the air also.
Decomposers are essential because without them, all of the carbon on the
planet would eventually become locked up in dead carcasses and other trash.
Decay permits carbon to be released back into the food web. Carbon
is also stored in fossil fuels, such as coal,
petroleum, and natural gas. When these are burned, carbon dioxide
is also released back into the air. Volcanoes and fires also release
large amounts of CO2 into the atmosphere. Carbon dioxide
can dissolve in water, where some of it is later returned back into the
atmosphere. The rest can be taken to form calcium carbonate, which
builds up shells, rocks, and skeletons of protozoans and coral.
How have humans interfered with the carbon cycle?
Mainly, we have drastically altered the carbon cycle
by destroying forests and other forms of vegetation without replanting.
Pop quiz:
How much of the earth's tropical rain forests
have been destroyed by human interference so far (as of 1997)?