| Term | Definition |
| Abiotic | Non-living factors in an ecosystem. |
| Biotic | Living factors in an ecosystem. |
| population | All members of one kind of organism living in the same location. |
| community | Many populations of organisms living together in the same ecosystem. |
| desert | An arid and hot terrestrial ecosystem. |
| forest | A wooded terrestrial ecosystem. |
| ocean | A salt water aquatic ecosystem. |
| stream | A fresh water aquatic ecosystem. |
| estuary | A brackish water aquatic ecosystem. |
| rock and ants | An abiotic biotic interaction. |
| fish and microorganisms | A biotic-biotic interaction. |
| herbivores | Plant eaters. |
| carnivores | Animal eaters. |
| omnivores | Plant and animal eaters. |
| producers | Plants that produce their own food. |
| consumers | Animals that need other plants and animals for food. |