Curriculum resources can be expensive—but not this one. An online textbook offers informational text for a complete high school Biology course. Topics include energy flow, body system, genetics, and evolution.

Understand the role that the carbon cycle plays in the ecosystem.

Useful introduction to the carbon cycle with a diagram and a discussion of the effects of carbon dioxide on the greenhouse effect and global warming.

A step-by-step discussion of the stages in the carbon cycle. Each step includes a diagram further explaining the processes involved, as well as pictures depicting combustion, respiration, photosynthesis, and decomposition.