Across
- 5. branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
- 7. to or derived from living matter.
- 9. being capable of being renewed
- 13. something in its original or existing state
- 14. production and discharge of something, especially gas or radiation
- 16. organic material used as a plant fertilizer
- 19. natural home or environment of an animal, plant, or other organism
- 20. as paper, cans, and bottles, that is left lying in an open or public place
Down
- 1. (water, air, or a place) with harmful or poisonous substances
- 2. to or determined by the sun
- 3. something, especially an environmentally or culturally important place from harm or destruction
- 4. discarded objects in such a way as to create a product of higher quality or value than the original
- 6. to be maintained at a certain rate or level
- 8. colorless unstable toxic gas
- 10. a species,family, or other group of animals or plants having no living members; no longer in existence
- 11. layer of gases that surround the planet
- 12. surroundings or conditions in which a person, animal, or plant lives or operates
- 15. biological community of interacting organisms and their physical environment
- 17. again
- 18. place to dispose of refuse and other waste material by burying it and covering it over with soil, especially as a method of filling in or extending usable land