完整版环境科学交叉关系学科56章重点句词汇.docx

完整版环境科学交叉关系学科56章重点句词汇.docx

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完整版环境科学交叉关系学科56章重点句词汇

第五章环境和生物间的相互作用Interactions:

EnvironmentsandOrganisms

Thescienceofecologyisthestudyofthewaysorganismsinteractwitheachother,andwiththeirnonlivingsurroundings.

Ecologydealswiththewaysinwhichorganismsareadaptedtotheirsurroundings,howtheymakeuseofthesesurroundings,andhowanareaisalteredbythepresenceandactivitiesoforganisms.

Allorganismsaredependentonotherorganismsinsomeway.

Everythingthataffectsanorganismduringitslifetimeiscollectivelyknownasitsenvironment.

Abioticfactorscanbeorganizedintoseveralbroadcategories:

energy,nonlivingmatter,andprocessesthatinvolvetheinteractionsofnonlivingmatterandenergy.

Allorganismsrequireasourceofenergytomaintainthemselves.Theultimatesourceofenergyforalmostallorganismsisthesun.

Allformsofliferequireatomsofelementssuchascarbon,nitrogen,andphosphorus,andmoleculessuchaswatertoconstructandmaintainthemselves.

Organismsconstantlyobtainthesematerialsfromtheirenvironment.Theatomsbecomepartofanorganism'sbodystructureforashorttimeperiod,andeventuallyallofthemarereturnedtotheenvironmentthroughrespiration,excretion,ordeathanddecay.

Thestructureandlocationofthespaceorganismsinhabitisalsoanimportantabioticaspectoftheirenvironment.

Importantecologicalprocessesinvolveinteractionsofmatterandenergy.

Theclimate（averageweatherpatternsoveranumberofyears）ofanareainvolvesenergyintheformofsolarradiationinteractingwiththematterthatmakesuptheEarth.

Thebioticfactorsofanorganism'senvironmentincludeallformsoflifewithwhichitinteracts.

Althoughorganismsinteractwiththeirsurroundingsinmanyways,certainfactorsmaybecriticaltoaparticularspecies'success.Ashortageorabsenceofthisfactorrestrictsthesuccessofthespecies;thus,itisknownasalimitingfactor.

Thelimitingfactorformanyspeciesoffishesistheamountofdissolvedoxygeninthewater.

Theenvironmentinfluencestheorganism,andorganismsaffecttheenvironment.

Thehabitatofanorganismisthespacethattheorganisminhabits,theplacewhereitlives（itsaddress）.

Thenicheofanorganismisthefunctionalroleithasinitssurroundings（itsprofession）.

GenesaredistinctpiecesofDNAthatdeterminethecharacteristicsanindividualdisplays.

Apopulationisconsideredtobealltheorganismsofthesamekindfoundwithinaspecificgeographicregion.

Aspeciesisapopulationofalltheorgantismspotentiallycapableofreproducingnaturallyamongthemselvesandhavingoffspringthatalsoreproduce.

Theprocessthatleadstothisclosefitbetweenthecharacteristicsorganismsdisplayandthedemandsoftheirenvironmentisknownasnaturalselection.

naturalselectionisthemechanismthatcausesevolutiontooccur.

Whenwelookattheeffectsofnaturalselectionovertime,wecanseeconsiderablechangeinthecharacteristicsofaspeciesandkindsofspeciespresent.Somechangestakethousandsormillionsofyearstooccur.Others,suchasresistancetopesticides,canoccurinafewyears.

Scientistshavecontinuouslyshownthatthistheoryofnaturalselectioncanexplainthedevelopmentofmostaspectsofthestructure,function,andbehavioroforganisms.Itisthecentralideathathelpsexplainhowspeciesadapttotheirsurroundings.Whenwediscussenvironmentalproblems,itishelpfultounderstandthatspecieschangeandthatastheenvironmentischanged,eithernaturallyorbyhumanaction,somespecieswilladapttothenewconditionswhileotherswillnot.

Theenvironmentinwhichorganismsexistdoesnotremainconstantoverlongtimeperiods.Thosespeciesthatlackthegeneticresourcestocopewithachangingenvironmentgoextinct.Extinctionisthelossofanentirespeciesandisacommonfeatureoftheevolutionoforganisms.

Naturalselectionisconstantlyatworkshapingorganismstofitachangingenvironment.

Itisclearthathumanshavehadasignificantimpactontheextinctionofmanykindsofspecies.

Whereverhumanshavemodifiedtheenvironmentfortheirpurposes（farming,forestry,cities,hunting,andintroducingexoticorganisms）,speciesaretypicallydisplacedfromthearea.Iflargeareasaremodified,entirespeciesmaybedisplaced.Ultimately,humansarealsosubjecttoevolutionandthepossibilityofextinctionaswell.

Coevolutionistheconceptthattwoormorespeciesoforganismscanreciprocallyinfluencetheevolutionarydirectionoftheother.Inotherwords,organismsaffecttheevolutionofotherorganisms.Sinceallorganismsareinfluencedbyotherorganisms,thisisacommonpattern.

Ecologistslookatorganismsandhowtheyinteractwiththeirsurroundings.

Onecommonkindofinteractioncalledpredationoccurswhenoneorganism,knownasapredator,killsandeatsanother,knownastheprey.

Asecondtypeofinteractionbetweenspeciesiscompetition,inwhichtwoorganismsstrivetoobtainthesamelimitedresource.

Symbiosisisaclose,long-lasting,physicalrelationshipbetweentwodifferentspecies.Therearethreedifferentcategoriesofsymbioticrelationships:

parasitism,commensalism,andmutualism.

Ifweexamineouractivities,wecanseethatwehavecomplicatedinteractionswithotherorganisms.

Predator----Humansthroughouttheworlduseanimalsasfood.

Herbivore----Humansrelyonmanykindsofplantsastheirprimarysourceoffood.

Scavenger----Scavenginginvolvesfindingandconsuminganimalsthatarealreadydead.

Commensalism-----Humansfindthemselvesonbothsidesofcommensalrelationships.

Parasitism----Althoughhumansdonotliveinoronotherlivingthings,wedoengageinrelationshipsthatareparasiticinnature.

Mutualism----Humanshavemanymutualisticrelationshipswithplantsandanimals.

Competition----HumansareincompetitionwithallotherorganismsonEarth.Asweconvertlandandaquaticresourcestoouruses,wedepriveotherorganismsofwhattheyneedtosurvive.

Acommunityisanassemblageofalltheinteractingpopulationsofdifferentspeciesoforganismsinanarea.

Anecosystemisadefinedspaceinwhichinteractionstakeplacebetweenacommunity,withallitscomplexinterrelationships,andthephysicalenvironment.

Whileitiseasytoseethatthephysicalenvironmentplaceslimitationsonthekindsoforganismsthatcanliveinanarea,itisalsoimportanttorecognizethatorganismsimpacttheirphysicalsurroundings.

Everysystemhaspartsthatarerelatedtooneanotherinspecificways.

Producersareorganismsthatareabletousesourcesofenergytomakecomplex,organicmoleculesfromthesimpleinorganicsubstancesintheirenvironment.

Primaryconsumers,alsoknownasherbivores,areanimalsthateatproducers（plantsorphytoplankton）asasourceoffood.

Secondaryconsumersorcarnivoresareanimalsthateatotheranimals.

Decomposersareorganismsthatusenonlivingorganicmatterasasourceofenergyandrawmaterialstobuildtheirbodies.

Wheneveranorganismshedsapartofitself,excreteswasteproducts,ordies,itprovidesasourceoffoodfordecomposers.

Sincedecomposerscarryonrespiration,theyareextremelyimportantinrecyclingmatterbyconvertingorganicmattertoinorganicmaterial.

Manysmallanimals,fungi,andbacteriafillthisniche.

Akeystonespeciesisonethathasacriticalroletoplayinthemaintenanceofspecificecosystems.

Somespecieshavepivotalroles,andtheireliminationorseverereductioncansignificantlyalterecosystems.

Theenergystoredinthemoleculesofproducersistransferredtootherorganismswhentheproducersareeaten.Eachstepintheflowofenergythroughanecosystemisknownasatrophiclevel.Producers（plants,algae,phytoplankton）constitutethefirsttrophiclevel,andherbivoresconstitutethesecondtrophiclevel.Carnivoresthateatherbivoresarethethir,trophiclevel,andcarnivoresthateatother".carnivoresarethefourthtrophiclevel.

Asenergyflowsthroughanecosystem,itpassesthroughseverallevelsknownastrophiclevels.Eachtrophiclevelcontainsacertainamountofenergy.Eachtimeenergyflowstoanothertrophiclevel,approximately90percentoftheusefulenergyislost,usuallyasheattothesurroundings.Therefore,inmostecosystems,highertrophiclevelscontainlessenergyandfewerorganisms.

Thepassageofenergyfromonetrophicleveltothenextasaresultofoneorganismconsuminganotherisknownasafoodchain.

Whenseveralfoodchainsoverlapandintersect,theymakeupafoodweb.

Allmatterismadeupofatoms.Theseatomsarecycledbetweenthelivingandnonlivingportionsofanecosystem.Theactivitiesinvolvedinthecyclingofatomsincludebiological,geological,andchemicalprocesses.Therefore,thesenutrientcyclesareoftencalledbiogeochemicalcycles.

Alllivingthingsarecomposedoforganicmoleculesthatcontainatomsoftheelementcarbon.Thecarboncycleincludestheprocessesandpathwaysinvolvedincapturinginorganiccarbon-containingmolecules,convertingthemintoorganicmoleculesthatareusedbyorganisms,andtheultimatereleaseofinorganiccarbonmoleculesbacktotheabioticenvironment.

Fossilfuels（coal,oil,andnaturalgas）arepartofthecarboncycleaswell.

Atonetime,thesematerialswereorganicmoleculesinthebodiesoflivingorganisms.

Theorganismswereburiedandtheorganiccompoundsintheirbodiesweremodifiedbygeologicforces.Thus,thecarbonatomspresentinfossilfuelswereremovedtemporarilyfromtheactive,short-termcarboncycle.Whenweburnfossilfuels,thecarbonreenterstheactivecarboncycle.A