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.
Primary producer- first producer of energy-rich compounds that are later used by other organisms
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
Chemosynthesis- process in which chemical energy is used to produce carbohydrates
Heterotroph- organism that obtains food by consuming other living things; also called a consumer
Consumer- organism that relies on other organisms for its energy and food supply; also called a heterotroph
Detritus- material made up of decaying bits of plant and animal material
Food chain- a series of steps in an ecosystem in which organisms transfer energy by eating and being eaten
Phytoplankton- photosynthetic algae found near the surface of the ocean
Food web- network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem
Trophic level- each step in a food chain or web
Ecological pyramid- illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or web
Biomass- total amount of living tissue within a given trophic level
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
Nutrient- chemical substance that an organism needs to sustain life
Nitrogen fixation- process of converting nitrogen gas into nitrogen compounds that plants can absorb and use
Denitrification- process by which bacteria convert nitrates into nitrogen gas
Limiting nutrient- single essential nutrient that limits productivity in an ecosystem.