| A | B |
|---|
| ecosystem | an association of living organisms and their physical environmental |
| ecology | the study of relationships among organisms in ecosystems |
| primary consumer | an organism that eats producers |
| secondary consumer | an organism that eats primary consumers |
| tertiary consumer | an organism that eats secondary consumers |
| ecological pyramid | a diagram that shows the biomass of organisms at each trophic level |
| biomass | a measure of the mass of organisms within a region divided by the area of that region |
| watershed | an ecosystem where all water runoff drains into a single river or stream |
| transpiration | evaporation of water from the leaves of a plant |
| greenhouse effect | the process by which certain gases (principally water, carbon dioxide, and methane) trap heat that would otherwise escape the earth and radiate into space |
