BIOL208 Study Guide - Final Guide: Trophic Cascade, Terrestrial Ecosystem, Nitrogen Fixation

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL208
• Professor: Audrey Reid

Document Summary

Trophic levels: the position of an organism in a food web. Tertiary consumers = level four (only really exist in aquatic env) Trophic interactions: transfer of energy from one trophic level to another (typically through eating) Trophic pyramids: uses biomass to determine the amount of energy in each trophic level, about a 10% transfer since not all of one level is consumed and turned into biomass in the next level. Also, only some parts of prey are consumed, not the entire organism. Trophic cascades: when a change in the pop size of a species in one trophic level alters the populations in other trophic levels. Trophic cascades caused by primary producers: most communities are controlled by both types of cascade effects. Primary production: the fixation of energy by autotrophs. The biggest source of primary production is photosynthesis. Primary productivity: the rate of primary production in an ecosystem is called primary productivity.