Across
- 2. salted water
- 4. smoke mixed with fog
- 6. DNA and RNA are called
- 7. used in nitrification
- 10. compound of hydrogen and carbon
- 11. living organisms on earth from the _ component
- 14. glass building which usually has plants
- 17. process of rotting
Down
- 1. fourth stage in water cycle
- 3. Green plants and animals are also known as
- 5. most important gaseous cycle
- 8. a toxic colorless gas surrounding the earth
- 9. emission of energy as electromagnetic waves
- 10. Water on earth
- 12. a rigid external covering for some animals
- 13. a source
- 15. 21% of atmosphere
- 16. air on the earth's surface