Biogeochemical cycle

Biogeochemical cycle connects with biological, geological, and chemical.

Bio: Living things are involved in the cycle.  The cycle might limit the organisms on earth.
Geo: Rocks, nonliving things, and evironments are part of the cycles.
Chemical:  oxygen, carbon, hydrogen, and nitrogen cannot be used unless the elements are in a chemical form that cells can take up.

http://www.geography4kids.com/files/cycles_intro.html