Across
- 2. the draining away of water from the surface of an area of land
- 7. colourless unstable toxic gas formed from oxygen.
- 8. process of burning something.
- 11. using up a resource.
- 12. a large natural or artificial lake used as a source of water supply.
- 13. fuel a natural fuel such as coal or gas.
- 15. cycle the process by which oxygen released into the atmosphere by photosynthetic organisms
- 16. when a plant absorbs water in its roots
- 17. process of turning from liquid to vapor.
- 20. involving or requiring free oxygen.
Down
- 1. person or thing eating something else.
- 3. fixing they contain symbiotic bacteria called rhizobia within nodules in their root systems
- 4. permeation of a liquid into something by filtration.
- 5. organism that decomposes organic material.
- 6. the action or process of precipitating a substance from a solution.
- 9. total mass of organism in a given area or volume
- 10. not derived from living organisms.
- 14. process of oxidizing or being oxidized.
- 18. a leguminous plant.
- 19. rain made sufficiently by acid from the atmosphere.