Across
- 5. A chemical substance that an organism needs to sustain life
- 10. A network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem
- 13. The process by which bacteria converts nitrates into nitrogen gas
- 15. A process used by plants and other autotrophs to capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches
- 16. A material made up of decaying bits of plant and animal material
Down
- 1. An organism that relies on other organisms for its energy and food supply; also called a heterotroph
- 2. A process of converting nitrogen gas into nitrogen compounds that plants can absorb and use
- 3. First producer of energy-rich compounds that are later used by other organisms
- 4. A model of the relative amounts of energy or matter contained within each trophic level in a given food chain or food web
- 6. An organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer
- 7. A series of steps in an ecosystem in which organisms transfer energy by eating and being eaten
- 8. The total amount of living tissue within a given trophic level
- 9. An organism that obtains food by consuming other living things; also called consumers
- 11. The process in which elements, chemical compounds, and other forms of matter are passed from one part of the biosphere to another
- 12. A process in which chemical energy is used to produce carbohydrates
- 14. Each step in a food chain or food web