| A | B |
|---|
| biome | a large region characterized by a specific type of climate and certain types of plant and animal communities |
| savanna | a grassland that often has scattered trees and that is found in tropical and subtropical areas where seasonal rains, fires, and drought happen |
| desert | a region that has little or no plant life, long periods without rain, and extreme temperatures; usually found in hot climates |
| tundra | a treeless plain found in the Arctic, in the Antarctic, or on the tops of mountains that is characterized by very low winter temperatures and short, cool summers |
| plankton | the mass of mostly microscopic organisms that float or drift freely in freshwater and marine environments |
| estuary | an area where fresh water from rivers mixes with salt water from the ocean |
| littoral zone | the shallow zone of a lake or pond where light reaches the bottom and nurtures plants |
| open water zone | the zone of a pond or lake that extends from the littoral zone and that is only as deep as light can reach |
| deep water zone | the zone of a lake or pond below the open-water zone, where no light reaches |
| wetland | an area of land that is periodically underwater or whose soil contains a great deal of moisture |
| marsh | a treeless wetland ecosystem where plants such as grasses grow |
| swamp | a wetland ecosystem in which shrubs and trees grow |
