Earth is the only planet known to show signs of life. Living beings are found on the habitable part of Earth, called the "biosphere." The balance in the biosphere is maintained by constant exchanges of matter and energy between the lithosphere, hydrosphere, and atmosphere.
Phosphorous and Nitrogen Cycles Earth Science, General Science
The Environment Earth Science, General Science
IS IT REAL: LIFE ON MARS General Science
Earth and the Moon Earth Science, General Science
Amazing Planet : Destructive Forces Earth Science, General Science
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