当前位置:考试网  > 试卷库  > 外语类  > 英语专业考试  > 专业英语八级  > AsGilbertWhite,Darwin,andothersobservedlongago,allspeciesappeartohavetheinnatecapacitytoincreasetheirnumbersfromgenerationtogeneration.Thetaskforecologistsistountangletheenvironmentaandbiologicalfactorsthatholdthisintrinsiccapacityforpopulationgrowthincheckoverthelongrun.Thegreatvarietyofdynamicbehaviorsexhibitedbydifferentpopulationmakesthistaskmoredifficult:sompopulationsremainroughlyconstantfromyeartoyear;othersexhibitregularcyclesofabundanceandscarcity;stillothersvarywildly,withoutbreaksandcrashesthatareinsomecasesplainlycorrelatedwiththeweather,andinothercasesnot.Toimposesomeorderonthiskaleidoscopeofpatterns,oneschoolofthoughtproposesdividingpopulationsintotwogroups.Theseecologistspositthattherelativelysteadypopulationshavedensity-dependentgrowthparameters;thatis,ratesofbirth,death,andmigrationwhichdependstronglyonpopulationdensity.Thehighlyvaryingpopulationshavedensity-independentgrowthparameters,withvitalratesbuffetedbyenvironmentalevents;theseratesfluctuateinawaythatiswhollyindependentofpopulationdensity.Thisdichotomyhasitsuses,butitcancauseproblemsiftakentooliterally.Foronething,nopopulationcanbedrivenentirelybydensity-independentfactorsallthetime.Nomatterhowseverelyorunpredictablybirth,death,andmigrationratesmaybefluctuatingaroundtheirlong-termaverages,iftherewerenodensity-dependenteffects,thepopulationwould,inthelongrun,eitherincreaseordecreasewithoutbound(barringamiraclebywhichgainsandlossescanceledexactly)。Putanotherway,itmaybethatonaverage99percentofalldeathsinapopulationarisefromdensity-independentcauses,andonlyonepercentfromfactorsvaryingwithdensity.Thefactorsmakinguptheonepercentmayseemunimportant,andtheircausemaybecorrespondinglyhardtodetermine.Yet,whetherrecognizedornot,theywillusuallydeterminethelong-termaveragepopulationdensity.Inordertounderstandthenatureoftheecologist’sinvestigation,wemaythinkofthedensity-dependenteffectsongrowthparametersasthesignalecologistsaretryingtoisolateandinterpret,onethattendstomakethepopulationincreasefromrelativelylowvaluesordecreasefromrelativelyhighones,whilethedensity-independenteffectsacttoproducenoiseinthepopulationdynamics.Forpopulationsthatremainrelativelyconstant,orthatoscillatearoundrepeatedcycles,thesignalcanbefairlyeasilycharacterizedanditseffectsdescribed,eventhoughthecausativebiologicalmechanismmayremainunknown.Forirregularlyfluctuatingpopulations,wearelikelytohavetoofewobservationstohaveanyhopeofextractingthesignalfromtheoverwhelmingnoise.Butitnowseemsclearthatallpopulationsareregulatedbyamixtureofdensity-dependentanddensity-independenteffectsinvaryingproportions. 1.Theauthorofthetextisprimarilyconcernedwith [A]Discussingtwocategoriesoffactorsthatcontrolpopulationgrowthandassessingtheirrelativeimportance. [B]Describinghowgrowthratesinnaturalpopulationsfluctuateovertimeandexplainingwhythesechangesoccur. [C]Proposingahypothesisconcerningpopulationsizeandsuggestingwaystotestit. [D]Posingafundamentalquestionaboutenvironmentalfactorsinpopulationgrowthandpresentingsomecurrentlyacceptedanswer. 2.Itcanbeinferredfromthetextthattheauthorconsidersthedichotomydiscussedtobe [A]Applicableonlytoerraticallyfluctuatingpopulations. [B]instrumental,butonlyifitslimitationsarerecognized. [C]Dangerouslymisleadinginmostcircumstances. [D]Acompleteandsufficientwaytoaccountforobservedphenomena. 3.tothetext,allofthefollowingbehaviorshavebeenexhibitedbydifferentpopulationsEXCEPT [A]Roughlyconstantpopulationlevelsfromyeartoyear. [B]Regularcyclesofincreasesanddecreasesinnumbers. [C]Erraticincreasesinnumberscorrelatedwiththeweather. [D]Uncheckedincreasesinnumbersovermanygenerations. 4.Thediscussionconcerningpopulationinthethirdparagraphservesprimarilyto [A]Demonstratethedifficultiesecologistsfaceinstudyingdensity-dependentfactorslimitingpopulationgrowth. [B]Advocatemorerigorousstudyofdensity-dependentfactorsinpopulationgrowth. [C]Provethatthedeathratesofanypopulationareneverentirelydensity-independent. [D]underlinetheimportanceofevensmalldensity-dependentfactorsinregulatinglong-termpopulationdensities. 5.Inthetext,theauthordoesallofthefollowingEXCEPT [A]Citetheviewsofotherbiologists. [B]Defineabasicproblemthatthetextaddresses. [C]Presentconceptualcategoriesusedbyotherbiologists. [D]Describetheresultsofaparticularstudy.
试题预览

AsGilbertWhite,Darwin,andothersobservedlongago,allspeciesappeartohavetheinnatecapacitytoincreasetheirnumbersfromgenerationtogeneration.Thetaskforecologistsistountangletheenvironmentaandbiologicalfactorsthatholdthisintrinsiccapacityforpopulationgrowthincheckoverthelongrun.Thegreatvarietyofdynamicbehaviorsexhibitedbydifferentpopulationmakesthistaskmoredifficult:sompopulationsremainroughlyconstantfromyeartoyear;othersexhibitregularcyclesofabundanceandscarcity;stillothersvarywildly,withoutbreaksandcrashesthatareinsomecasesplainlycorrelatedwiththeweather,andinothercasesnot.Toimposesomeorderonthiskaleidoscopeofpatterns,oneschoolofthoughtproposesdividingpopulationsintotwogroups.Theseecologistspositthattherelativelysteadypopulationshavedensity-dependentgrowthparameters;thatis,ratesofbirth,death,andmigrationwhichdependstronglyonpopulationdensity.Thehighlyvaryingpopulationshavedensity-independentgrowthparameters,withvitalratesbuffetedbyenvironmentalevents;theseratesfluctuateinawaythatiswhollyindependentofpopulationdensity.Thisdichotomyhasitsuses,butitcancauseproblemsiftakentooliterally.Foronething,nopopulationcanbedrivenentirelybydensity-independentfactorsallthetime.Nomatterhowseverelyorunpredictablybirth,death,andmigrationratesmaybefluctuatingaroundtheirlong-termaverages,iftherewerenodensity-dependenteffects,thepopulationwould,inthelongrun,eitherincreaseordecreasewithoutbound(barringamiraclebywhichgainsandlossescanceledexactly)。Putanotherway,itmaybethatonaverage99percentofalldeathsinapopulationarisefromdensity-independentcauses,andonlyonepercentfromfactorsvaryingwithdensity.Thefactorsmakinguptheonepercentmayseemunimportant,andtheircausemaybecorrespondinglyhardtodetermine.Yet,whetherrecognizedornot,theywillusuallydeterminethelong-termaveragepopulationdensity.Inordertounderstandthenatureoftheecologist’sinvestigation,wemaythinkofthedensity-dependenteffectsongrowthparametersasthesignalecologistsaretryingtoisolateandinterpret,onethattendstomakethepopulationincreasefromrelativelylowvaluesordecreasefromrelativelyhighones,whilethedensity-independenteffectsacttoproducenoiseinthepopulationdynamics.Forpopulationsthatremainrelativelyconstant,orthatoscillatearoundrepeatedcycles,thesignalcanbefairlyeasilycharacterizedanditseffectsdescribed,eventhoughthecausativebiologicalmechanismmayremainunknown.Forirregularlyfluctuatingpopulations,wearelikelytohavetoofewobservationstohaveanyhopeofextractingthesignalfromtheoverwhelmingnoise.Butitnowseemsclearthatallpopulationsareregulatedbyamixtureofdensity-dependentanddensity-independenteffectsinvaryingproportions.

1.Theauthorofthetextisprimarilyconcernedwith

[A]Discussingtwocategoriesoffactorsthatcontrolpopulationgrowthandassessingtheirrelativeimportance.

[B]Describinghowgrowthratesinnaturalpopulationsfluctuateovertimeandexplainingwhythesechangesoccur.

[C]Proposingahypothesisconcerningpopulationsizeandsuggestingwaystotestit.

[D]Posingafundamentalquestionaboutenvironmentalfactorsinpopulationgrowthandpresentingsomecurrentlyacceptedanswer.

2.Itcanbeinferredfromthetextthattheauthorconsidersthedichotomydiscussedtobe

[A]Applicableonlytoerraticallyfluctuatingpopulations.

[B]instrumental,butonlyifitslimitationsarerecognized.

[C]Dangerouslymisleadinginmostcircumstances.

[D]Acompleteandsufficientwaytoaccountforobservedphenomena.

3.tothetext,allofthefollowingbehaviorshavebeenexhibitedbydifferentpopulationsEXCEPT

[A]Roughlyconstantpopulationlevelsfromyeartoyear.

[B]Regularcyclesofincreasesanddecreasesinnumbers.

[C]Erraticincreasesinnumberscorrelatedwiththeweather.

[D]Uncheckedincreasesinnumbersovermanygenerations.

4.Thediscussionconcerningpopulationinthethirdparagraphservesprimarilyto

[A]Demonstratethedifficultiesecologistsfaceinstudyingdensity-dependentfactorslimitingpopulationgrowth.

[B]Advocatemorerigorousstudyofdensity-dependentfactorsinpopulationgrowth.

[C]Provethatthedeathratesofanypopulationareneverentirelydensity-independent.

[D]underlinetheimportanceofevensmalldensity-dependentfactorsinregulatinglong-termpopulationdensities.

5.Inthetext,theauthordoesallofthefollowingEXCEPT

[A]Citetheviewsofotherbiologists.

[B]Defineabasicproblemthatthetextaddresses.

[C]Presentconceptualcategoriesusedbyotherbiologists.

[D]Describetheresultsofaparticularstudy.

查看答案
收藏
纠错
正确答案:

ABDDD

答案解析:

暂无解析

你可能感兴趣的试题

Writing:

Astatementgoesthat“onlythroughmistakescantherebediscoveryorprogress”.Towhatdegreedoyouagreewiththisstatement?Writeanessayofabout400words.

Inthefirstpartofyouressayyoushouldstateclearlyyourmainargument,andinthesecondpartyoushouldsupportyourargumentwithappropriatedetails.Inthelastpartyoushouldbringwhatyouhavewrittentoanaturalconclusionormakeasummary.

Youshouldsupplyanappropriatetitleforyouressay.

Markswillbeawardedforcontent,organization,grammarandappropriateness.Failuretofollowtheaboveinstructionsmayresultinalossofmarks.

Writing:

InChina,torestorelostpropertytoitsoriginalownerisregardedasoneofthemostcherishedvirtues.However,thedraftpropertyrightslawstipulatesthatpropertyOwnersshouldpaysomemoneytotheonewhoreturnstheproperty.Isitadeviationfromtraditionalvalues?Writeacompositionofabout400wordstostateyourview.

Inthefirstpartofyouressayyoushouldstateclearlyyourmainargument,andinthesecondpartyoushouldsupportyourargumentwithappropriatedetails.Inthelastpartyoushouldbringwhatyouhavewrittentoanaturalconclusionormakeasummary.

Youshouldsupplyanappropriatetitleforyouressay.

Markswillbeawardedforcontent,organization,grammarandappropriateness.Failuretofollowtheaboveinstructionsmayresultinalossofmarks.

____thecenterofourplanetarysystemwasconsideredasheresybythechurchintheMiddleAges.

Ibelievethatremark____fromwhatyousaidyesterday.

Hearrived____London____acoldwinternight.

热门试题 更多>
试题分类: 行政法与行政诉讼法(一)
练习次数:1次
试题分类: 社会学概论
练习次数:0次
试题分类: 行政管理学
练习次数:3次
试题分类: 行政管理学
练习次数:0次
试题分类: 机关管理
练习次数:0次
试题分类: 市政学
练习次数:0次
试题分类: 市政学
练习次数:0次
试题分类: 行政管理学
练习次数:0次
扫一扫,手机做题