NSES Content Standard D  Earth and Space Science: Origin and evolution of the earth system Grades 9-12, page 190 Evidence for one-celled forms of life--the bacteria--extends back more than 3.5 billion years. The evolution of life caused dramatic changes in the composition of the Earth's atmosphere, which did not originally contain oxygen.

 
Benchmark 4C The Physical Setting: Processes that Shape the Earth
Grades 9-12, page 74
Plants alter the earth's atmosphere by removing carbon dioxide from it, using the carbon to make sugars and releasing oxygen. This process is responsible for the oxygen content of the air.

Benchmark 5F The Living Environment: Evolution of Life
Grades 9-12, page 125
Life on earth is thought to have begun as simple, one-celled organisms about 4 billion years ago. During the first 2 billion years, only single-cell microorganisms existed, but once cells with nuclei developed about a billion years ago, increasingly complex multicellular organisms evolved.