短文閱讀練習(xí)題及參考答案GRE考試

第第頁短文閱讀練習(xí)題及參考答案GRE考試

Perhapsthefactthatmanyofthesefirststudiesconsideredonlyalgaeofasizethatcouldbecollectedinanet(netphytoplankton),apracticethatoverlookedthesmallerphytoplankton(nannoplankton)thatwenowknowgrazersaremostlikelytofeedon,ledtoade-emphasisoftheroleofgrazersinsubsequentresearch.Increasingly,asintheindividualstudiesofLund,Round,andReynolds,researchersbegantostresstheimportanceofenvironmentalfactorssuchastemperature,light,andwatermovementsincontrollingalgalnumbers.Theseenvironmentalfactorswereamenabletofieldmonitoringandtosimulationinthelaboratory.Grazingwasbelievedtohavesomeeffectonalgalnumbers,especiallyafterphytoplanktongrowthratesdeclinedattheendofbloomperiods,butgrazingwasconsideredaminorcomponentofmodelsthatpredictedalgalpopulationdynamics.

Thepotentialmagnitudeofgrazingpressureonfreshwaterphytoplanktonhasonlyrecentlybeendeterminedempirically.StudiesbyHargraveandGeenestimatednaturalcommunitygrazingratesbymeasuringfeedingratesofindividualzooplanktonspeciesinthelaboratoryandthencomputingcommunitygrazingratesforfieldconditionsusingtheknownpopulationdensityofgrazers.Thehighestimatesofgrazingpressurepostulatedbytheseresearcherswerenotfullyaccepted,however,untilthegrazingratesofzooplanktonweredetermineddirectlyinthefield,bymeansofnewe*perimentaltechniques.Usingaspeciallypreparedfeedingchamber,Haneywasabletorecordzooplanktongrazingratesinnaturalfieldconditions.Intheperiodsofpeakzooplanktonabundance,thatis,inthelatespringandinthesummer,Haneyrecordedma*imumdailycommunitygrazingrates,fornutrient-poorlakesandboglakes,respectively,of6.6percentand114percentofdailyphytoplanktonproduction.Cladoceranshadhighergrazingratesthancopepods,usuallyaccountingfor80percentofthecommunitygrazingrate.Theseratesvariedseasonally,reachingthelowestpointinthewinterandearlyspring.Haney’sthoroughresearchprovidesconvincingfieldevidencethatgrazerscane*ertsignificantpressureonphytoplanktonpopulation.

20.TheauthormostlikelymentionsHardy’sprincipleofanimale*clusioninorderto

(A)giveane*ampleofonetheoryabouttheinteractionofgrazersandphytoplankton

(B)defendthefirsttheoryofalgaldefensesagainstgrazing

(C)supportthecontentionthatphytoplanktonnumbersarecontrolledprimarilybyenvironmentalfactors

(D)demonstratethesuperiorityoflaboratorystudiesofzooplanktonfeedingratestootherkindsofstudiesofsuchrates

(E)refuteresearcherswhobelievedthatlownumbersofphytoplanktonindicatedthegrazingeffectoflownumbersofzooplankton

21.Itcanbeinferredfromthepassagethatthe“firsttheories”ofgrazercontrolmentionedinline4wouldhavebeenmoreconvincingifresearchershadbeenableto

(A)observehighphytoplanktonnumbersundernaturallakeconditions

(B)discovernegativecorrelationsbetweenalgaeandzooplanktonnumbersfromtheirfieldresearch

(C)understandthecentralimportanceofenvironmentalfactorsincontrollingthegrowthratesofphytoplankton

(D)makeverifiablecorrelationsofcauseandeffectbetweenzooplanktonandphytoplanktonnumbers

(E)inventlaboratorytechniquesthatwouldhaveallowedthemtobypasstheirfieldresearchconcerninggrazercontrol

22.Whichofthefollowing,iftrue,wouldcallintoquestionHardy’sprincipleofanimale*clusion?

(A)Zooplanktonarenottheonlyorganismsthatareaffectedbyphytoplanktonrepellents.

(B)Zooplanktone*clusionisunrelatedtophytoplanktonpopulationdensity.

(C)Zooplanktonpopulationdensityishigherduringsomepartsoftheyearthanduringothers.

(D)Netphytoplanktonaremorelikelytoe*cludezooplanktonthanarenannoplankton.

(E)Phytoplanktonnumberscanbestronglyaffectedbyenvironmentalfactors.

23.Theauthorwouldbelikelytoagreewithwhichofthefollowingstatementsregardingthepressureofgrazersonphytoplanktonnumbers?

I.Grazingpressurecanvaryaccordingtotheindividualtypeofzooplankton.

II.Grazingpressurecanbelowerinnutrient-poorlakesthaninboglakes.

III.Grazingtendstoe*ertaboutthesamepressureasdoestemperature.

(A)Ionly

(B)IIIonly

(C)IandIIonly

(D)IIandIIIonly

(E)I,II,andIII

24.ThepassagesuppliesinformationtoindicatethatHargraveandGeen’sconclusionregardingthegrazingpressuree*ertedbyzooplanktononphytoplanktonnumberswasmostsimilartotheconclusionregardinggrazingpressurereachedbywhichofthefollowingresearchers?

(A)Hardy

(B)Lund

(C)Round

(D)Reynolds

(E)Haney

25.Itcanbeinferredfromthepassagethatonewayinwhichmanyoftheearlyresearchersongrazercontrolcouldhaveimprovedtheirdatawouldhavebeento

(A)emphasizetheeffectsoftemperature,ratherthanoflight,onphytoplankton

(B)disregardnannoplanktonintheiranalysisofphytoplanktonnumbers

(C)collectphytoplanktonofallsizesbeforeanalyzingthee*tentofphytoplanktonconcentration

(D)recognizethatphytoplanktonotherthannetphytoplanktoncouldbecollectedinanet

(E)understandthecrucialsignificanceofnetphytoplanktoninthedietofzooplankton

26.Accordingtothepassage,HargraveandGeendidwhichofthefollowingintheire*periments?

(A)Theycomparedthegrazingratesofindividualzooplanktonspeciesinthelaboratorywiththenaturalgrazingratesofthesespecies.

(B)Thehypothesizedaboutthepopulationdensityofgrazersinnaturalhabitatsbyusingdataconcerningthepopulationdensityofgrazersinthelaboratory.

(C)Theyestimatedthecommunitygrazingratesofzooplanktoninthelaboratorybyusingdataconcerningthenaturalcommunitygrazingratesofzooplankton.

(D)Theyestimatedthenaturalcommunitygrazingratesofzooplanktonbyusingdataconcerningtheknownpopulationdensityofphytoplankton.

(E)Theyestimatedthenaturalcommunitygrazingratesofzooplanktonbyusinglabo