|
The
biosphere is the part of the Earth occupied by living organisms. This includes
parts of the atmosphere, the watery part of the earth's surface, called the hydrosphere,
and the rocks and minerals forming the solid part, called the lithosphere.
There are about 40 chemical elements present in organisms. These materials circulate
through the ecosystem. They move through the ecosystem as simple elements and
as more complex chemical compounds. All are important for the maintenance of life.
These materials are cycled repeatedly through the ecosystem. These cycles include
the nitrogen cycle, the water cycle, and the carbon cycle.
|
More about cycles |
 |
|
One
of nature's most critical cycles is the continual exchange of carbon dioxide and
oxygen among plants and animals. This "recycling service" is provided
by nature free of charge. If this capacity to recycle is exceeded, there is no
alternative available.
The
word "cycles" conveys how nature works. Many organisms, for example butterflies,
have life cycles, entering different stages to deal with different conditions.
Other cycles include the monthly and daily cycles.
|
