| A | B |
|---|
| water cycle | the process of evaporation, condensation, and precipitation |
| evaporation | molecules of liquid water absorb energy and change to the gas state |
| condensation | gas changes into a liquid |
| precipitation | rain, snow, sleet, or hail |
| nitrogen fixation | free nitrogen is changed into a usable form of nitrogen |
| nodules | bumps on the roots of some plants that contain nitorogen-fixing bacteria |
| succession | predictable changes that occur over time in a community |
| primary succession | series of changes that occur in an area where no ecosystem previously existed |
| pioneer species | the first organisms to populate an area |
| secondary succession | series of changes that occur after a disturbance in an existing ecosystem |
