B— Continued 



biocoenosis — Approximately equal to a 

 biotic community of plants (phyto- 

 coenosis) and animals (zoocoenosis). See 

 also biogenocoenosis and ecosystem. 



bioecology— A collective term that includes 

 plant and animal ecology as one 

 discipline. 



bioenergetic— Of or relating to the energy 

 flow of a population of organisms. 



biogenic deposits — A geological deposit 

 resulting from the physiological activity 

 of organisms such as calcareous algae. 



biogeochemical cycling — The cycling of 

 chemical constituents through a biolog- 

 ical system. 



biogeocoenosis— Any unit that includes all 

 the organisms, i.e., the biotic community 

 in a given area interacting with the 

 physical environment so that a flow of 

 energy leads to clearly defined trophic 

 structure, biotic diversity and material 

 cycles within the system. See also 

 biocoenosis and ecosystem. 



biogeography— The study of geographical 

 distribution of plants and animals and 

 the reasons for the distribution. 



biological clock — A physiological mecha- 

 nism which allows an organism to 

 estimate time. See circadian rhythm. 



biological magnification — The concentra- 

 tion of certain substances up a food 

 chain. A very important mechanism in 

 concentrating pesticides and heavy 

 metals in organisms such as fish. 



bioluminescene— The production of light, 

 without sensible heat, by living orga- 

 nisms as a result of a chemical reaction 

 either within certain cells or organisms 

 or extra-cellularly by some form of 

 secretion. 



biomass— The amount of living material in a 

 unit area for a unit time. Also standing 

 crop, standing stock, live-weight. 



biomass pyramids— A graphic representa- 

 tion of biomass at each trophic level. It 

 does not indicate importance of specific 

 organisms. 



biome— A major community of plants and 

 animals associated with a stable environ- 

 mental life zone or region (e.g., Northern 

 Coniferous Forest or Great Plains). 



biophages— Those organisms which obtain 

 nourishment from other organisms (e.g., 

 predators, parasites, and pathogens). 



biosphere— The transitional zone between, 

 and including parts of the earth and the 

 atmosphere where all living organisms 

 commonly dwell. 



biostrome— Bedded structures such as shell 

 beds consisting of, or built mainly by 

 sedentary organisms. 



biota— The living part of a system (flora 

 and fauna). 



biotic community— (1) All of the plant and 

 animal populations occupying a given 

 area, usually named after the dominant 

 (in size or numbers) plant or animal in 

 area. (2) An integrated, mutually 

 adjusted assemblage of organisms inhab- 

 iting a natural area. The assemblage may 

 or may not be self-sufficient and is 

 considered to be in a state of dynamic 

 equilibrium. 



