| A | B |
|---|
| biotic | features of the environment that are alive or were once alive. |
| abiotic | nonliving, physical features of the environment, including air, water, sunlight, soil, temperature, and climate. |
| atmosphere | air surrounding Earth is made up of gases, including 78 percent nitrogen, 21 percent oxygen, and .03 percent carbon dioxide. |
| soil | mixture of mineral and rock particles, the remains of dead organisms, air, and water that forms the topmost layer of Earth's crust and supports plant growth. |
| climate | average weather cdonditions of an area over time, including wind, temperature, and rainfall or other types of precipitation. |
| evaporation | process that takes place when a liquid changes to a gas.i |
| condensation | process that takes place when a gas changes to a liquid. |
| water cycle | model describing how water moves from Earth's surface to the atmosphere and back to the surface again through evaporation, condensation, and precipitation. |
| nitrogen filxation | process in which some types of bacteria can form the nitrogen compounds that plants need. |
| nitrogen cycle | model describing how nitrogen moves from the atmosphere to the soil, to living organisms, and then back to the atmosphere. |
| chemosynthesis | process in which producers make energy-rich nutrient molecules from chemicals. |
| food web | model that shows the complex feeding relationships among organisms in a community. |
| energy pyramid | model that shows the amount of energy available at each feeding level in an ecosystem. |
