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OXYGEN and CARBON
CYCLES
Like most living things, you need oxygen to
survive.
The atmosphere, which is 20 percent oxygen, supplies you and other air-breathing
organisms with this vital gas.
Oxygen from the atmosphere that has dissolved in water is breathed by
fish and other aquatic organisms.
Clearly, living things would have used up the available oxygen supply
in the atmosphere millions of years ago if something did not return the oxygen to the
air.
But what could that something be?
Consider this:
When
you inhale, you take in oxygen.
When you exhale, you release the waste gas carbon
dioxide.
If something used carbon dioxide and released oxygen, it would balance your use of
oxygen.
That something is producers such as green plants and certain
microorganisms.
These producers use carbon dioxide gas, water, and the energy of sunlight to make
carbon containing compounds that are often referred to as
"food."
During the food making process, the producers also produce oxygen, which is released
into the environment.
Through this process, known as the oxygen cycle, there is always a plentiful supply of
oxygen available for air-breathing organisms.
But what happens to the carbon in
food?
How is it transformed back into carbon dioxide?
In order to extract energy from
food, organisms must digest the food, or break it down into simpler
substances.
This process ultimately produces water and carbon dioxide, which are released back
into the environment.
Look at the illustrations below that demonstrates the oxygen and carbon
cycles.
Look at the illustration below and explain what is happening in the Oxygen and
Carbon Dioxide Cycles.
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