| A | B |
|---|
| Food chain | a series of steps in which organisms transfer energy by eating and being eaten |
| Phytoplankton | floating algae; primary producers |
| Food web | a network of feeding (eating) interactions |
| Convert | to change from one form to another |
| Zooplankton | small animals that swim and eat algae in the water |
| Tophic level | each step in a food chain or food web |
| Ecological pyramid | a way to showing the amount of energy or matter that is in each trophic level of a food web |
| Biomass | the total amount of living tissue within a trophic level |
| Pyramid of biomass | shows a picture of the AMOUNT OF LIVING ORGANIC MATTER available at each trophic level in an ecosystem |
| Pyramid of numbers | shows the relative NUMBER OF INDIVIDUAL ORGANISMS at each tropic level in an ecosystem |
| Biogeochemical cycles | how elements pass from one organisms to another and through different parts of the biosphere |
| Flow of energy in an ecosystem | one-way |
| Flow of matter | recycled within and between ecosystems |
| Nutrient | the chemical substances that an organisms needs to sustain life |
| Nitrogen fixation | the process in which bacteria converts nitrogen gas into ammonia |
| Limiting nutrient | a nutrient whose supply limits productivity |
