3-2 Energy flow

Producers The sun is the main energy source of life on earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Autotrophs can make their own food

Photosynthesis Light energy powers reactions that convert CO 2 and H 2 O into sugars + O 2 On land: plants Oceans: algae, cyanobacteria CO 2 + H 2 O + sunlight C 6 H 12 O 6 + O 2

Chemosynthesis Some bacteria can use the energy in H 2 S to make food Found in sulfur vents, hot springs

Tube worms in an underwater thermal vent

Consumers/ heterotrophs Must eat to survive. Omnivores: eat plants and animals Detritivores: feed on dead matter Decomposers: break down organic matter

Food chain Energy flows in only one direction- from the sun to producers, to consumers, etc.

Terrestrial and marine food chains

Food webs Several food chains linked together Shows how energy moves through a community A change to one part of the web affects all the others Salt marsh food web

Energy pyramids Energy is lost as heat or used for growth. Only 1/10th of the energy is available for the next trophic level

Biomass pyramid

Some questions What happens to a community if the number or output of the producers is lowered, say in a drought? What would happen if the decomposers died? What happens if the top predators are killed by man?