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雅思閱讀模擬試題精選1.Washing,brushingandvarnishingfossils—allstandardconservationtreatmentsusedbymanyfossilhuntersandmuseumcuratorsalike—vastlyreducesthechancesofrecoveringancientDNA.2.Instead,excavatorsshouldbehandlingatleastsomeoftheirbountywithgloves,andfreezingsamplesastheyarefound,dirtandall,concludesapaperintheProceedingsoftheNationalAcademyofSciencestoday.3.AlthoughmanypalaeontologistsknowanecdotallythatthisisthebestwaytouptheoddsofextractinggoodDNA,Eva-MariaGeigloftheJacquesMonodInstituteinParis,F(xiàn)rance,andhercolleagueshavenowshownjusthowimportantconservationpracticescanbe.Thisinformation,theysay,needstobehammeredhomeamongthepeoplewhoareactuallyoutinthefielddiggingupbones.4.Geiglandhercolleagueslookedat3,200-year-oldfossilbonesbelongingtoasingleindividualofanextinctcattlespecies,calledanaurochs.ThefossilsweredugupatasiteinFranceattwodifferenttimes—eitherin1947,andstoredinamuseumcollection,orin,andconservedinsterileconditionsat-20oC.5.Theteam'sattemptstoextractDNAfromthe1947bonesallfailed.Thenewlyexcavatedfossils,however,allyieldedDNA.6.Becausetheboneshadbeenburiedforthesameamountoftime,andinthesameconditions,theconservationmethodhadtobetoblamesaysGeigl."AsmuchDNAwasdegradedinthese57yearsasinthe3,200yearsbefore,"shesays.Washin,washout7.Becausemanypalaeontologistsbasetheirworkontheshapeoffossilsalone,theirmethodsofconservationarenotdesignedtopreserveDNA,Geiglexplains.8.Thebiggestproblemishowtheyarecleaned.Fossilsareoftenwashedtogetheron-siteinalargebath,whichcanallowwater—andcontaminantsintheformofcontemporaryDNA—topermeateintotheporousbones."NotonlyistheauthenticDNAgettingwashedout,butcontaminationisgettingwashedin,"saysGeigl.9.MostancientDNAspecialistsknowthisalready,saysHendrikPoinar,anevolutionarygeneticistatMcMasterUniversityinOntario,Canada.Butthatdoesn'tmeanthatbestpracticehasbecomewidespreadamongthosewhoactuallyfindthefossils.10.GettingholdoffossilsthathavebeenpreservedwiththeirDNAinmindreliesoncloserelationshipsbetweenlab-basedgeneticistsandtheexcavators,sayspalaeogeneticistSvanteP??booftheMaxPlanckInstituteforEvolutionaryAnthropologyinLeipzig,Germany.Andthatonlyoccursinexceptionalcases,hesays.11.P??bo'steam,whichhasbeensequencingNeanderthalDNA,continuallyfacestheseproblems."WhenyouwanttostudyancienthumanandNeanderthalremains,there'sabigissueofcontaminationwithcontemporaryhumanDNA,"hesays.12.Thisdoesn'tmeanthatallmuseumspecimensarefatallyflawed,notesP??bo.TheNeanderthalfossilsthatwererecentlysequencedinhisownlab,forexample,hadbeenpartofamuseumcollectiontreatedinthetraditionalway.ButP??boiskeentoseesamplesoffossilsfromeverymajorfindpreservedinlinewithGeigl'srecommendations—justincase.Warmandwet14.Muchhumanculturaldevelopmenttookplaceintemperateregions.DNAdoesnotsurvivewellinwarmenvironmentsinthefirstplace,andcanvanishwhenfossilsarewashedandtreated.Forthisreason,Geiglsays,mostancientDNAstudieshavebeendoneonpermafrostsamples,suchasthewoollymammoth,oronremainsshelteredfromtheelementsincoldcaves—includingcavebearandNeanderthalfossils.15.Betterconservationmethods,andafocusonfreshfossils,couldboostDNAextractionfrommoredelicatespecimens,saysGeigl.Andthatcouldshedmorelightonthestoryofhumanevolution.(640wordsnature)
GlossaryPalaeontologists古生物學家Aurochs歐洲野牛Neanderthal(人類學)尼安德特人,舊石器時代旳古人類。Permafrost(地理)永凍層-Questions1-6AnswerthefollowingquestionsbyusingNOMORETHANTHREEWORDSforeachanswer.1.Howdidpeopletraditionallytreatfossils?2.WhatsuggestionsdoGeiglandhercolleaguesgiveonwhatshouldbedonewhenfossilsarefound?3.Whatproblemsmaybeposediffossilbonesarewashedon-site?NameONE.4.WhatcharacteristicdofossilboneshavetomakethemsusceptibletobecontaminatedwithcontemporaryDNAwhentheyarewashed?5.Whatcouldbebetterunderstoodwhenconservationtreatmentsareimproved?6.Thepassagementionedseveralanimalspeciesstudiedbyresearchers.Howmanyofthemarementioned?Questions7-11Dothefollowingstatementsagreewiththeinformationgiveninthepassage?PleasewriteTRUEifthestatementagreeswiththewriterFALSEifthestatementdoesnotagreewiththewriterNOTGIVENifthereisnoinformationaboutthisinthepassage7.IntheirpaperpublishedintheProceedingsoftheNationalAcademyofSciences,GeiglandhercolleagueshaveshownwhatconservationpracticesshouldbefollowedtopreserveancientDNA.8.ThefossilbonesthatGeiglandhercolleaguesstudiedareallfromthesameaurochs.9.Geneticistsdon‘thavetoworkonsite.10.OnlynewlyexcavatedfossilbonesusingnewconservationmethodssuggestedbyGeiglandhercolleaguescontainancientDNA.11.Paaboisstillworriedaboutthepotentialproblemscausedbytreatmentsoffossilsintraditionalway.Questions12-13CompletethefollowingthestatementsbychoosingletterA-Dforeachanswer.12.“Thisinformation”inparagraph3indicates:[A]ItiscriticaltofollowproperpracticesinpreservingancientDNA.[B]ThebestwayofgettinggoodDNAistohandlefossilswithgloves.[C]Fossilhuntersshouldwearhome-madehammerswhilediggingupbones.[D]Manypalaeontologistsknowhowoneshoulddointreatingfossils.13.ThestudyconductedbyGeiglandhercolleaguessuggests:[A]thefactthatancientDNAcannotberecoveredfromfossilbonesexcavatedinthepast.[B]thecorrelationbetweentheamountofburyingtimeandthatoftherecoveredDNA.[C]thepaceatwhichDNAdegrades.[D]thecorrelationbetweenconservationpracticesanddegradationofDNA.
1.washing,brushing,varnishing見第一段。2.handlingwithgloves/freezingsamples(anyoneofthetwo)見第二段。3.losingauthenticDNA/beingcontaminated/contamination(anyoneofthethree)見第八段“NotonlyistheauthenticDNAgettingwashedout,butcontaminationisgettingwashedin”(答beingcontaminated或contamination比較保險)4.theyareporousporous旳意思是多孔旳。見第八段“……whichcanallowwater—andcontaminantsintheformofcontemporaryDNA—topermeateintotheporousbones.”5.humanevolution見第十五段。其中“shedlightonsth”旳意思是使某事顯得非常清晰,使人理解某事。6.4分別為第四段旳“anextinctcattlespecies,calle
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