| A | B |
|---|
| Food Chain | path of energy transfer from one organism to another |
| Sun | source of most life-giving energy |
| Plants | often the first link in the food chain |
| First-order consumers | organisms that eat producers |
| Seond order consumers | eat first order consumers |
| decomposers | organisms that get their energy by breaking down dead plant and animal matter |
| food web | formed by overlapping food chains |
| carbon dioxide-oxygen cycle | During cell respiration, living things use oxygen, given off by plants, to break down food and obtain energy. When organisms carry out this process, carbon dioxide is given off into the air and the water. |
| cell respiration | the use of oxygen to break down carbon compounds and release energy |
| photosynthesis | plants use carbon dioxide, water, and energy from the Sun to make food in the form of sugar |
| Water cycle | the constant movement of water |
| evaporation | the process by which liquid water changes to water vapor |
| condensation | the process by which water vapor changes to liquid water |
| transpiration | water vapor is released through leaves |
| proteins | compounds that act as the building blocks of living things |
| nitrogen | needed to make proteins |
| nitrogen cycle | nitrogen gas is converted to a usable form and eventually returned to the atmosphere as nitrogen gas |
