Chapter 4 Vocabulary

4. process by which bacteria convert nitrates into nitrogen gas
5. An organism that makes its own food
8. process of converting nitrogen gas into nitrogen compounds that plants can absorb and use
11. A community of organisms where there are several interrelated food chains
13. Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems
16. organism that obtains energy from the foods it consumes; also called a consumer
17. An organism that obtains energy by feeding on other organisms

1. total amount of living tissue within a given trophic level
2. diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web
3. A series of steps in which organisms transfer energy by eating and being eaten
6. Each step in a food chain or food web
7. single essential nutrient that limits productivity in an ecosystem
9. chemical substance that an organism needs to sustain life
10. Plants use the sun's energy to convert water and carbon dioxide into sugars
12. process in which elements, chemical compounds, and other forms of matter are passed from one part of the biosphere to another
14. Dead organic matter
15. producer first producer of energy-rich compounds that are later used by other organisms
17. process in which chemical energy is used to produce carbohydrates