Nutrient cycles

1234567891011121314151617181920
Across
  1. 3. Performed by a living organism
  2. 4. Formation of clouds, lightning, flow of water
  3. 6. Chemical substances an organisms needs to live
  4. 11. Large deposits of CO2 are burned to make these
  5. 13. a type of bacteria that makes it so animals can use nitrogen
  6. 15. An effect caused by too much CO2 in the air
  7. 18. Animals use carbon dioxide in this process
  8. 19. Occurs when acidic water falls to the ground
  9. 20. main deposit of phosphorus
Down
  1. 1. An important chemical that makes up DNA
  2. 2. using fossil fuels, clearing land, fertilizers
  3. 5. Amount of living tissue within a trophic level
  4. 7. Volcanic eruptions, plate tectonics, etc.
  5. 8. basins collect the phosphorus in the soil
  6. 9. The main regulator of carbon dioxide
  7. 10. The percent of nitrogen in the atmosphere
  8. 12. Caused by too much phosphorus in the water
  9. 14. mixture of floating algae
  10. 16. used in the process of photosynthesis
  11. 17. A smaller source of carbon dioxide