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Across 1. the study of the relationships between organisms and their environment 5. coal, oil, and natural gas are this type of resource 7. eight masses that circle the sun 10. plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water 12. part of the upper atmosphere containing a relatively high concentration of ozone that absorbs solar ultraviolet radiation 15. season 18. not dirty 19. the act of preserving, guarding, and protecting 21. pollution of the atmosphere 22. ____________, reuse, recycle 23. clearing of trees 25. mutually beneficial relationship between different organisms or people 26. a forest with heavy annual rainfall 29. where most garbage eventually ends up 30. gender of mosquitoes that bite people 32. 2/3 of the Earth's surface is covered with 34. biological community of interacting organisms and their physical environment 36. a day to remember to protect our planet 37. another word for garbage 39. large body of water surrounded by land 40. blowing air

Down 2. worlds largest reef system 3. rain, snow, sleet, or hail that falls to the ground 4. pollution of the water in rivers and lakes 6. life-supporting component of air 8. grouping of trees 9. processes by which water circulates between the earth's oceans, atmosphere, and land 11. natural home or environment of an animal, plant, or other organism 13. ceasing to exist 14. seriously at risk of extinction 16. month 17. Earth's ___________ is about seven billion people 20. large natural stream of water flowing in a channel to the sea, a lake, or another stream 24. natural fuel such as coal or gas, formed in the geological past from the remains of living organisms 26. capable of being replenished 27. place of refuge or safety 28. our sun is actually a 31. turn off when you leave a room 33. to use over again 35. _________ continents 38. condensed moisture of the atmosphere falling visibly in separate drops