Biosphere:
According to dictionary.com a biosphere is 1) the part of the earth's crust, waters, and atmosphere that supports life or 2) the ecosystem comprising the entire earth and the living organisms that inhabit it. An example of a biosphere is the dirt we walk on all the way to the atmosphere (hydrosphere and lithosphere). So that includes all living organisms, water, and the air. That is about 3.7 miles (six kilometers) thick.
![Picture](/uploads/1/8/3/5/18354217/750495602.jpg?702)
Shows what a biosphere is, the earth is an example.
Picture from: http://www.amerigas.com/amerigas-propane-blog/wp-content/uploads/2012/03/earth.jpg