a model that shows one set of feeding relationships among living things

food chain

the original source of all Earth's energy

sun

a model that shows many different feeding relationships among living things

food web

the transfer of energy from one organism to another through a food chain or web

energy flow

a model that shows one set of feeding relationships among living things in water

aquatic food chain

a model that shows one set of feeding relationships among living things on land

terrestrial food chain

a model that shows the available amount of energy in each trophic layer in an ecosystem

energy pyramid

a process in which nitrogen in the atmosphere enters the soil and becomes part of living organisms then eventually returns to the atmosphere

nitrogen cycle

a natural cycle in which mainly carbon dioxide is incorporated into living tissue through photosynthesis and returned to the atmosphere by respiration, decay of dead organisms, and the burning of fossil fuels

carbon cycle

a waste product made by cells of the body; a gas in the air made of carbon and oxygen atoms

carbon dioxide

any organism that can create its own food from inorganic materials

autotroph

an organism that cannot create its own energy and must instead rely on consuming nutrients from other organisms

heterotroph

the position an organism occupies at each level of the food chain

trophic level

an organism that makes its own food; an organism that does not consume other plants or animals

producer

an organism that eats other living things to get energy; an organism that does not produce its own food

consumer

an animal that consumes only plants

herbivore

an animal that eats only other animals

carnivore

an animal that eats plants as well as other animals

omnivore

a non-mutual relationship in which one organism benefits and the other is harmed

parasitism

a relationship in which one species lives off the other and both organisms benefit

mutualism