| A | B |
|---|
| limiting factor | any factor limiting the survival and productivity of organisms |
| succession | natural orderly process in the community of an ecosystem characterized by population growth or reduction |
| primary succession | development of living communities from bare rock |
| climax community | stable, mature community that undergoes little ecological succession |
| biome | large areas with the same type of climax community; examples include deserts and tropical rain forests |
| photic zone | portion of the marine biome shallow enough for the sun to penetrate; has abundant life in high productivity |
| aphotic zone | marine biome that never receives sunlight because of water depth; has intense water pressure; fish populating this zone have adapted to scarce food and life in darkness |
| estuary | coastal body of water in which both freshwater and saltwater mix; provides excellent food supply and shelter for young fish |
| intertidal zone | part of the shoreline between the high and low tide lines |
| plankton | microscopic organisms found floating in the photic zone; form the base of the marine food chain |
| tundra | treeless biome south of the northern polar ice cap; has a short growing season; temperatures never rise above freezing |
| permafrost | layer of permanently frozen ground found under the topmost layer of soil in the tundra |
| taiga | biome located south of the tundra |
| desert | driest biome south of the taiga; generally receives less than 25 cm of annual rainfall |
| grassland | biome composed of large communities of grasses and other small plants |
| temperate forest | biome in which an even amount of precipitation falls in all four seasons |
| tropical rain forest | most biological diverse terrestrial biome; receives from 200 to 400 cm of annual rainfall and has year-round warm temperatures; plants include ferns, orchids, and trees |
