| A | B |
|---|
| Water Cycle | The continous movement of water between the Earth's surface and the air. |
| Evaporation | The changing of a liquid to a gas. |
| Condensation | The changing of a gas into a liquid. |
| Precipitation | Any form of water that falls from the atmosphere and reaches the ground. |
| Watershed | An area from which water is drained. |
| Runoff | Precipitation that flows into rivers, lakes and streams. |
| Groundwater | Runoff water that settles underground. |
| Carbon Cycle | The continous exchange of carbon among living things. |
| Nitrogen Cycle | The trapping of nitrogen gas into compounds in the soil then returned to the air. |
| Compost | A mixture of dead organic material that can be used as fertilizer. |
| Extinct Species | When the last member of a species dies. |
| Endangered Species | When a species is in danger of becoming extinct. |
| Threatened Species | Species with low numbers that could become endangered. |
| Succession | The process of one ecosystem changing into a new one. |
| Pioneer Species | The forst organisms living in a lifeless area. |
| Pioneer Community | The first living community in an otherwise lifeless area. |
| Climax Community | The final stage of succession. |
| Secondary Succession | The begining of a new community where a new one had already existed. |
