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Across 1. a producer 4. the process in which nitrates are converted to nitritesand then to nitrogen gas 5. A layer of ozone found in the stratosphere helps to screen out ultraviolet radiation. 8. the total dry mass of all the living material in an ecosystem 11. an organism that feeds on other animals 12. a group of individuals of the same species occupying a given area at a certain time 15. slowing decomposing plant matter produced in low-oxygen environments 16. a representation of energy flow in food chains and webs 19. the biological or living components of the biosphere 22. the chemcial reaction that occurs when a substance reacts very quickly with oxygen to releasae energy 24. a molecule that has a positive and a negative end 25. a scientific study of energy transformations, described by laws 26. the removal of soluble minerals by percolation 27. an animal that eats both plants and other animals 28. a chemical that is essential to living things

Down 1. the non-living components of the biosphere 2. a community and its physical and chemical environment 3. waste from plants and animals, including their dead remains 6. the number of species in an ecosystem 7. the loss of water through plant leaves 9. the top level of the region below the ground that is saturated with water 10. cultivation of a single species 13. an organism that feeds on detritus 14. a representation of the feedinig relationships among organisms in an ecosystem 17. an organism that can synthesize organic componds from inorganic chemicals with using solar energy 18. an organism that must eat producers or other consumers to survive 20. a term used to describe the extent to which surface can reflect light 21. the populations of all species that occupy a habitat 23. an animal that eats only plants 24. an organsim that can produce its own food