Across
- 4. A family or species having no living members.
- 7. Related to or determined by the sun.
- 8. To maintain something in its original or current state.
- 11. The gases surround the Earth.
- 13. To protect something, like an environment, from harm or destruction.
- 17. The branch of biology that studies the relations of organisms to one another and to their surroundings.
- 18. A place to dispose of waste materials by burying them in soil.
- 19. To convert waste into a reusable material.
- 20. Decayed organic material to be used as plant fertilizer.
Down
- 1. Trash left in an open or public area.
- 2. Able to be maintained at a certain rate.
- 3. The surroundings where a person, plant, or animal lives or operates.
- 5. Fresh air blowing onto the shore from the sea.
- 6. Something that can be reused
- 9. A biological community of interacting organisms and their environment.
- 10. The production or discharge of something, especially gas or radiation.
- 12. The natural home of a plant, animal, or other organism.
- 14. To reuse something as a product of higher value.
- 15. Something that relates to or is derived from living matter.
- 16. To contaminate water, air, or a place with harmful substances.