ps考试题目模拟试题及答案新GRE阅读考试模拟试题及答案.docx

ps考试题目模拟试题及答案新GRE阅读考试模拟试题及答案.docx

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ps考试题目模拟试题及答案新GRE阅读考试模拟试题及答案

ps考试题目模拟试题及答案【2018年新GRE阅读考试模拟试题及答案】

Manytheorieshavebeenformulatedtoexplaintheroleofgrazerssuchaszooplanktonincontrollingtheamountofplanktonicalgae（phytoplankton）inlakes.Thefirsttheoriesofsuchgrazercontrolweremerelybasedonobservationsofnegativecorrelationsbetweenalgalandzooplanktonnumbers.Alownumberofalgalcellsinthepresenceofahighnumberofgrazerssuggested,butdidnotprove,thatthegrazershadremovedmostofthealgae.Theconverseobservation,oftheabsenceofgrazersinareasofhighphytoplanktonconcentration,ledHardytoproposehisprincipleofanimalexclusion,whichhypothesizedthatphytoplanktonproducedarepellentthatexcludedgrazersfromregionsofhighphytoplanktonconcentration.Thiswasthefirstsuggestionofalgaldefensesagainstgrazing.

Perhapsthefactthatmanyofthesefirststudiesconsideredonlyalgaeofasizethatcouldbecollectedina（phytoplankton）,apracticethatoverlookedthesmallerphytoplankton（nannoplankton）thatwenowknowgrazersaremostlikelytofeedon,ledtoade-emphasisoftheroleofgrazersinsubsequentresearch.Increasingly,asintheindividualstudiesofLund,Round,andReynolds,researchersbegantostresstheimportanceofenvironmentalfactorssuchastemperature,light,andwatermovementsincontrollingalgalnumbers.Theseenvironmentalfactorswereamenabletofieldmonitoringandtosimulationinthelaboratory.Grazingwasbelievedtohavesomeeffectonalgalnumbers,especiallyafterphytoplanktongrowthratesdeclinedattheendofbloomperiods,butgrazingwasconsideredaminorponentofmodelsthatpredictedalgalpopulationdynamics.

Thepotentialmagnitudeofgrazingpressureonfreshwaterphytoplanktonhasonlyrecentlybeendeterminedempirically.StudiesbyHargraveandGeenestimatednaturalmunitygrazingratesbymeasuringfeedingratesofindividualzooplanktonspeciesinthelaboratoryandthenputingmunitygrazingratesforfieldconditionsusingtheknownpopulationdensityofgrazers.Thehighestimatesofgrazingpressurepostulatedbytheseresearcherswerenotfullyaepted,however,untilthegrazingratesofzooplanktonweredetermineddirectlyinthefield,bymeansofnewexperimentaltechniques.Usingaspeciallypreparedfeedingchamber,Haneywasabletorecordzooplanktongrazingratesinnaturalfieldconditions.Intheperiodsofpeakzooplanktonabundance,thatis,inthelatespringandinthesummer,Haneyrecordedmaximumdailymunitygrazingrates,fornutrient-poorlakesandboglakes,respectively,of6.6percentand114percentofdailyphytoplanktonproduction.Cladoceranshadhighergrazingratesthancopepods,usuallyaountingfor80percentofthemunitygrazingrate.Theseratesvariedseasonally,reachingthelowestpointinthewinterandearlyspring.Haney’sthoroughresearchprovidesconvincingfieldevidencethatgrazerscanexertsignificantpressureonphytoplanktonpopulation.

20.TheauthormostlikelymentionsHardy’sprincipleofanimalexclusioninorderto

（A）giveanexampleofonetheoryabouttheinteractionofgrazersandphytoplankton

（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’sprincipleofanimalexclusion?

（A）Zooplanktonarenottheonlyorganismsthatareaffectedbyphytoplanktonrepellents.

（B）Zooplanktonexclusionisunrelatedtophytoplanktonpopulationdensity.

（C）Zooplanktonpopulationdensityishigherduringsomepartsoftheyearthanduringothers.

（D）Netphytoplanktonaremorelikelytoexcludezooplanktonthanarenannoplankton.

（E）Phytoplanktonnumberscanbestronglyaffectedbyenvironmentalfactors.

23.TheauthorwouldbelikelytoaGREewithwhichofthefollowingstatementsregardingthepressureofgrazersonphytoplanktonnumbers?

I.Grazingpressurecanvaryaordingtotheindividualtypeofzooplankton.

II.Grazingpressurecanbelowerinnutrient-poorlakesthaninboglakes.

III.Grazingtendstoexertaboutthesamepressureasdoestemperature.

（A）Ionly

（B）IIIonly

（C）IandIIonly

（D）IIandIIIonly

（E）I,II,andIII

24.ThepassagesuppliesinformationtoindicatethatHargraveandGeen’sconclusionregardingthegrazingpressureexertedbyzooplanktononphytoplanktonnumberswasmostsimilartotheconclusionregardinggrazingpressurereachedbywhichofthefollowingresearchers?

（A）Hardy

（B）Lund

（C）Round

（D）Reynolds

（E）Haney

25.Itcanbeinferredfromthepassagethatonewayinwhichmanyoftheearlyresearchersongrazercontrolcouldhaveimprovedtheirdatawouldhavebeento

（A）emphasizetheeffectsoftemperature,ratherthanoflight,onphytoplankton

（B）disregardnannoplanktonintheiranalysisofphytoplanktonnumbers

（C）collectphytoplanktonofallsizesbeforeanalyzingtheextentofphytoplanktonconcentration

（D）recognizethatphytoplanktonotherthanphytoplanktoncouldbecollectedina

（E）understandthecrucialsignificanceofphytoplanktoninthedietofzooplankton

26.Aordingtothepassage,HargraveandGeendidwhichofthefollowingintheirexperiments?

（A）Theyparedthegrazingratesofindividualzooplanktonspeciesinthelaboratorywiththenaturalgrazingratesofthesespecies.

（B）Thehypothesizedaboutthepopulationdensityofgrazersinnaturalhabitatsbyusingdataconcerningthepopulationdensityofgrazersinthelaboratory.

（C）Theyestimatedthemunitygrazingratesofzooplanktoninthelaboratorybyusingdataconcerningthenaturalmunitygrazingratesofzooplankton.

（D）Theyestimatedthenaturalmunitygrazingratesofzooplanktonbyusingdataconcerningtheknownpopulationdensityofphytoplankton.

（E）Theyestimatedthenaturalmunitygrazingratesofzooplanktonbyusinglaboratorydataconcerningthegrazingratesofindividualzooplanktonspecies.

27.WhichofthefollowingisatruestatementaboutthezooplanktonnumbersandzooplanktongrazingratesobservedinHaney’sexperiments?

（A）WhilezooplanktonnumbersbegantodeclineinAugust,zooplanktongrazingratesbegantoincrease.

（B）AlthoughzooplanktonnumberswerehighinMay,grazingratesdidnotbeehighuntilJanuary.

（C）BothzooplanktonnumbersandgrazingrateswerehigherinDecemberthaninNovember.

（D）BothzooplanktonnumbersandgrazingrateswerelowerinMarchthaninJune.

（E）BothzooplanktonnumbersandgrazingrateswerehighestinFebruary.

答案ADBCECED

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