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Across 2. the sum total of all the different forms of genetic 5. when many new techniques began to be used to increase 7. the sum total of the genetically based variety of all 8. a mixture of chemicals causing the air to appear dirty 9. an area in the atmosphere containing high concentrations of 10. these won't regenerate or replace themselves 12. precipitation with a low pH 16. the wearing away of surface soil by wind and water 18. the number of different species in the biosphere 19. when an ecosystem is fragmented by development 21. to use resources without depleting them and 22. resources biotic or abiotic that can regenerate given 23. when a species disappears from all or part of its range 24. the spread of deserts caused by overgrazing or drought 25. large fields are planted with a single variety of plant year

Down 1. when concentrations of harmful substances 3. when a species population is in serious decline 4. they are introduced into an area where they don't 6. an unnatural harmful material found in the air or water or 11. the wise management of natural resources 13. when trees are removed from a wide area and not replaced 14. the variety of habitats, communities and ecological 15. an increased average temperature in the atmosphere 17. raising animals in water for human consumption 20. the practice of farming