Bio Lecture Notes 2

Bio Lecture Notes 2 - Ecosystems 13:28 Ecosystems consist...

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Ecosystems 13:28 Ecosystems consist of all the organisms living in a community as well as all the  abiotic factors which they interact Like populations and communities, the boundaries of ecosystems are usually  not discrete (not well defined) Regardless of the size, ecosystem dynamics typically involve two different  processes Energy flow: energy enters as sungligh (usually) and is turned into chemical  energy (biomass) by primary producers, energy flows up the food chain as  biomass is eaten, flows thru the ecosystem, is not recycled, ecosystems  require a continuous input of energy to persist Chemical cycling: chemical elements (C, N, P, etc.) cycle among abiotic and  biotic components, photosynthetic organisms incorporate these elements into  organic molecules, the elements are returned in inorganic from thru  metabolism of plants and animals and the breakdown of organic waste Energy and matter move thru ecosystems via the transfer of substances  during photosynthesis and feed habits? Ecosystems and physical laws A lot of the analysis of ecosystems derive from laws of chemistry and physics Principe of conservation of energy: energy cannot be created or destroyed o Plants and other photosynthetic organisms convert solar energy to  chemical energy, but the amount of energy does not change Second law of thermodynamics: some energy is lost as heat in any  conversion process o Metabolism can be energetically expensive process, with a lot of?? Ecologists view ecosystems as transfromers of energy and processors of  matter o The tropic level that ultimately supports all others are autotrophs (primary  producers) Plants, algae, photosynthetic prokaryotes o Most are photosynthetic organisms that use light energy to synthesize o Organisms above the primary producers are heterotrophs o Herbivores are primary consumers o Detritvores (decomposers) get their energy from non living organic  material
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o The amount of energy Ex. Most of solar radiation doesn’t make it to earth’s surface, that  which does only a very small amount actually hits primary producers,  has to be correct wave lengths as welll, only about 1% of visible light  that hits primary producers is converted to chemical energy o Gross primary production (GPP): the toal amount of light energy captured  by plants per unit time (includes the energy used by the plants to make  biomass and the energy used for cellular respiration) o Net primary production (NPP): the energy used to make biomass NPP= GPP-R NPP is important because the amount of energy available to  consumers (J/m2/yr) o
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