The big picture
| Idea | Rule |
|---|---|
| Ecosystem and its parts | Living things (biotic) plus non-living surroundings (abiotic) |
| Producers, consumers and decomposers | A producer makes food, a consumer eats it, a decomposer feeds on dead matter |
| Food chains and webs | A chain is a straight line of who eats whom; a web is chains that cross |
| Trophic levels | The producer is level 1; each next eater is one level higher |
| Flow of energy | About a tenth of the energy at one level reaches the next |
| Biological magnification | A chemical that does not break down builds up more at each level |
| Ozone depletion | Ozone blocks harmful UV; CFCs break it down and thin the layer |
| Managing garbage | Sort biodegradable waste from non-biodegradable waste, first |
Every living thing lives in an ecosystem. Each one makes food, eats food, or feeds on the dead. Food chains link living things, and chains cross into webs. Each step up a chain has a level. Energy shrinks by about nine-tenths at every level up. Some chemicals do the opposite, building up more and more. Two changes affect far more than one pond or field. One is a thinning ozone layer high in the sky. The other is a waste pile that sorting can shrink.
Chapter 13, Our Environment, in your Science book covers these ideas. You already know them.