| A | B |
|---|
| carbon dioxide/oxygen cycle | A natural cycle in which plants and other producers use carbon-dioxide and produce oxygen; and liiving things use oxygen and produce carbon-dioxide. |
| cell respiration | The process of using oxygen to break down carbon compounds and release energy. Animals and plants release carbon-dioxide as a waste product of cell respiration. |
| condensation | The process by which water vapor is changed to liquid water. It can occur on a glass containing ice cubes. |
| evaporation | The process by which liquid water changes to water vapor. |
| first-order consumers | Organisms that eat producers. |
| food chain | The flow of energy from one living organism to another in an ecosystem. Energy moves from producers to consumers in a food chain. |
| food web | The overlapping food chains that link producers, consumers, and decomposers in an ecosystem. Some in a food web eat both plants and animals. |
| herbavores | A consumer that eats only plants or other producers. Examples: squirrels, deer, rabbits, mice, and most insects. |
| nitrogen | A gas that makes up about 78% of Earth's atmosphere. It is needed to make proteins. |
| nitrogen cycle | The cycle through which nitrogen gas is changed into compounds that can be used by living things and then is returned to the atmosphere. |
| omnivores | Consumers that eat both plants and animals. Examples: turtles, woodpeckers, and tree creepers. |
| precipitation | Water that falls back to earth after it has condensed in the clouds. |
| proteins | Compounds that act as the building blocks of living things. They provide the body with materials that help cells grow and repair themselves. |
| transpiration | The process by which water is released through leaves in a plant. |
| water cycle | A continuous process in which water moves between the atmosphere and Earth's surface, including its use by living things. |
