Biology

Chapter 4 Ecosystems Vocabulary

1. Autotroph- 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.

2. Primary producer- first producer of energy-rich compounds that are later used by other organisms

3. Photosynthesis- process used by plants and other autotrophs to capture light energy and use it to power chemical reactions to convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches  

4. Chemosynthesis- process in which chemical energy is used to produce carbohydrates

5. Heterotroph- organism that obtains food by consuming other living things; also called a consumer

6. Consumer- organism that relies on other organisms for its energy and food supply; also called a heterotroph

7. Detritus- material made up of decaying bits of plant and animal material

8. Food chain- a series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

9. Phytoplankton- photosynthetic algae found near the surface of the ocean

10. Food web- network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

11. Trophic level- each step in a food chain or web

12. Ecological pyramid- illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or web

13. Biomass- total amount of living tissue within a given trophic level

14. Biogeochemical cycle- process in which elements, chemical compounds, and other forms of matter are passes from one organism to another and from one part of the biosphere to another 

15. Nutrient- chemical substance that an organism needs to sustain life

16. Nitrogen fixation- process of converting nitrogen gas into nitrogen compounds that plants can absorb and use

17. Denitrification- process by which bacteria convert nitrates into nitrogen gas

18. Limiting nutrient- single essential nutrient that limits productivity in an ecosystem.