| Term | Definition |
| biogeochemical cycles | a process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another |
| evaporation | the process by which water changes from a liquid into an atmospheric gas |
| transpiration | the loss of water from a plant through its leaves |
| nutrients | chemical substances that an organism needs to sustain life |
| nitrogen fixation | the process of converting nitrogen gas into ammonia |
| dentrification | the conversion of nitrates into nitrogen gas |