Biology 1001A Lecture : BIOLOGY LECTURE 24.docx

• School: Western University
• Department: Biology
• Course: Biology 1001A
• Professor: Tom Haffie

Document Summary

Community: all of the organisms living in some defined place. Ecosystem: a biotic community and its abiotic environment functioning as a system. 2 major activities in ecosystems: production and consumption. Production: new biomass being created from inorganic substances. Consumption: biomass which is already created is being converted into new forms of biomass. Consumers (heterotrophs- eats other things) - includes decomposers. In 99. 9% of ecosystems, energy comes from the sun. Exceptions: chemical energy, harvested by chemoautotrophs (usually in places where the sun doesn"t shine- deep sea vents). Chemical elements or compounds needed for growth or reproduction. Organic or inorganic (carbon containing or not) Energy flows from source through primary producers though consumers and decomposers. Ecological inefficiency: some energy is lost at each transfer between levels. Energy constantly being replaces from outside ecosystem. Harvesting efficiency < 100% (not all of the available food will be successfully be consumed) Proportion of available food that is consumed.