Across
- 3. a science that deals with the relationships between groups of living things and their environments
- 5. waste material; refuse or litter.
- 6. the action of clearing a wide area of trees.
- 7. the place in which a species normally lives
- 8. the planet on which we live
Down
- 1. use again or more than once.
- 2. the introduction of harmful materials into the environment.
- 4. occurs when energy is produced but not used