Earth Day

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Across
  1. 5. to be maintained
  2. 8. group of babies(cat)
  3. 10. branch of biology studying organisms
  4. 12. layer of gas around the earth's surface
  5. 13. place full of trash
  6. 14. not alive anymore
  7. 16. derived from living matter
  8. 18. to keep something safe
  9. 20. layer above the earth
Down
  1. 1. biological community
  2. 2. to use old things to make new
  3. 3. to make foul or unclean
  4. 4. production of discharge
  5. 6. surrounding conditions in which a person lives
  6. 7. able to use again __ energy
  7. 9. to collect objects that can be used again
  8. 11. place where animals live
  9. 15. to save something
  10. 17. converting organic materials into nutrients
  11. 19. sun