TPO36阅读文本和题目正式版

1、TPO361TheFirstEyePuttingadateonthefirstappearanceofeyesdependsonwhatonemeansbyeye.Ifthetermreferstoamulticellularorgan,evenifithasjustafewcells,thenbydefinition,eyescouldnotformbeforethereweremulticellu1aranimals.Butmanyprotists(anima1-like,plantlike,orfungus-1ikeunicel1ularorganismsthatrequireawate

2、r-basedenvironment)candetectlightbyusingaggregationsofpigmentmolecu1es,andtheyusethisinformationtomodifytheirmetabolicactivityormotility(theabilitytomovespontaneouslyandindependently).Oneofthefami1iarlivingexamples,probablyknowntoanyonewhohastakenabiologyclass,istheaquaticprotozoanEug1ena,whichhasan

3、eyespotnearitsmotilefIagellum(hair1ikestructure).Some1ivingprotistsareveryliketheirancestralformsembeddedinancientsedimentaryrocks,andthissimilaritysuggeststhattheabi1itytodetectlightandmodifybehaviorinresponsetolighthasbeenaroundforaverylongtime.Animalsarosefromoneofsuchunicel1u1arcreatures,perhaps

4、fromonea1readyspecia1izedforaprimitivekindofvision.AneyeisacollectionofcellsthatarespecializedforlightdetectionthroughthepresenceofphotosensitivepigmentaswellasameansofrestrictingthedirectionofincominglightthatwillstrikethephotosensitiveceIls.Thisdefinitionsaysnothingaboutimageformation,lenses,eyemo

5、vements,oranyoftheotherfeaturesweassociatewithourowneyes,butitdoesrecognizethesimplestformoffunctionalandanatomica1specialisationname1y,detectionoflight.Everythingelsecanbebuiltupfromthissimplebeginning,andsomeanimalsappeartohavehadeyesalmostfromthebeginningoftheanimalkingdom.Animalswerescarce600mi1

6、lionyearsagointhegeologica1eracalledthePrecambrian.Thereareveryfewfossilremainsfromthattime(thoughmorekeepturningup),andmostevidenceofthepresenceofanimalsisindirect,suchassmalltunnelsinrockthatcouldbeancientwormburrowings.Butjust50mi1lionyearsorso1ater,fossi1izedbitsandpiecesofanimalsabound,suggesti

7、ngthatagreatburstofevolutionarycreativityoccurredinthe50-million-yearinterval.Thissurgeofnew1ife,markedbyanabundanceofanimals,iscalledtheCambrianexp1osion.Thefirstdirectevidencefortheearlyoriginofeyescomesfromfossilsthatareabout530millionyearsold,atimeshortlyaftertheCambrianexp1osion;theywerefoundon

8、amountainsideinBritishColumbiainadepositknownastheBurgessSha1e.TheBurgessSha1efossilsareextraordinarilyimportantbecauseamongthemareremainsofsoft一bodiedcreatures,manyofthemlackingshellsandotherhardpartsthatfossilizeeasily.Consequently,theirpreservationislittleshortofmiraculous(asarethedelicatemethods

9、usedtoreconstructthree-dimensionalstructurefromthesef1attenedfossils),andtheyareoneofthefewknownrepositoriesofear1ysoft-bodiedanimals.NotalloftheBurgessanimalshadeyes.However,somedid.(Grossfeatureslocation,size,andhemisphericshapeareresponsibleforthedesignationofsomestructuresaseyes).Thereconstructe

10、deyesoftheseBurgessanimalslooksuperficiallylikeeyesofsome1ivingcrustaceans,particu1arlythoseofshrimpandcrabswhoseeyesaremountedonstalksthatimprovetherangeofvisionbyraisingtheeyesabovethesurfaceofthehead.TheeyesofsomeBurgessorganismssatonstalks;thoseof0therswereonorapartofthebodysurface.Oneanima1,Opa

11、binia,hadfiveeyes:two1ateralpairsandasing1emedia1eye；atleastoneofthelateralpairshadstalksthatcouldhavebeenmovable.AndsometrilobitelikeanimalsintheBurgessShalehadfacetedeyesmuchlikethoseoflaterfossiltrilobites.AlthoughthepresenceofeyesonsomeoftheBurgessanimalsindicatesthateyeshavebeenaroundforavery1o

12、ngtime,itisunlikelythatthesewerethefirsteyes;theyseemmuchtoolargeand(potential1y)we1ldevelopedtobebrandnewinventions.ThebestwecandoisputtheoriginofeyessomewherebetweenthebeginningoftheCambrianexplosion,about600millionyearsago,andthedeathoftheBurgessanimals,some530mi1lionyearsago.Paragraph1：Puttingad

13、ateonthefirstappearanceofeyesdependsonwhatonemeansbyeye.Ifthetermreferstoamu1ticellularorgan,evenifithasjustafewcells,thenbydefinition,eyescouIdnotformbeforethereweremultice1lularanima1s.Butmanyprotists(animal-like,plantlike,orfungus-likeunicel1ularorganismsthatrequireawater-basedenvironment)candete

14、ctlightbyusingaggregationsofpigmentmolecu1es,andtheyusethisinformationtomodifytheirmetabolicactivityormotility(theabilitytomovespontaneouslyandindependently).Oneofthefamiliarlivingexamples,probab1yknowntoanyonewhohastakenabiologyc1ass,istheaquaticprotozoanEuglena,whichhasaneyespotnearitsmotilefIagel

15、lum(hairlikestructure).Somelivingprotistsareveryliketheirancestralformsembeddedinancientsedimentaryrocks,andthissimi1aritysuggeststhattheabilitytodetectlightandmodifybehaviorinresponsetolighthasbeenaroundforavery1ongtime.Animalsarosefromoneofsuehunicellularcreatures,perhapsfromonealreadyspecializedf

16、oraprimitivekindofvision.1 .Thewordaggregations“inthepassageisclosestinmeaningtoParts.Reactions.Groups.Types.2 .Paragraph1supportsallofthefol1owingstatementsaboutprotistsEXCEPT:Somearemulticellular.Someareabletomove.Somehavepigmentmolecu1es.Theyliveinenvironmentsthatcontainmoisture.3. .Accordingtopa

17、ragraph1,whathavescientistsconc1udedfromthefactthatsome1ivingprotistsareveryliketheirancestralformsTheeyedidnotevo1veuntilmulticel1ularorganismsarose.Theabilitytodetect1ightandchangebehaviorinresponsetolighthasexistedforalongtime.Theancestralformsoftheselivingprotistslike1yhadaneyespotnearthemotilef

18、lagellum.Theancestralformsoftheselivingprotistsdependedprimarilyon1ightasthemechanismformodifyingtheirmetabolicactivityormotility.Paragraph2:Aneyeisacollectionofcellsthatarespecializedforlightdetectionthroughthepresenceofphotosensitivepigmentaswellasameansofrestrictingthedirectionofincominglightthat

19、willstrikethephotosensitivecel1s.Thisdefinitionsaysnothingaboutimageformation,lenses,eyemovements,oranyoftheotherfeaturesweassociatewithourowneyes,butitdoesrecognizethesimplestformoffunctionalandanatomicalspecia1isationnamely,detectionoflight.Everythinge1secanbebuiltupfromthissimp1ebeginning,andsome

20、animalsappeartohavehadeyesa1mostfromthebeginningoftheanimalkingdom.4. Paragraph2imp1ieswhichofthefollowingabouttheear1yeyesTheywereab1etodetectsimplemovementsa1mostfromthebeginningoftheirevolution.Theywerenotassensitivetolightasoncethought.Theycou1dnotformimages.Theircellshadmorephotosensitivepigmen

21、tthandohumaneyesParagraph3:Animalswerescarce600mil1ionyearsagointhegeo1ogicaleracalledthePrecambrian.Thereareveryfewfossilremainsfromthattime(thoughmorekeepturningup),andmostevidenceofthepresenceofanimalsisindirect,suchassmalltunnelsinrockthatcouldbeancientwormburrowings.Butjust50millionyearsorsolat

22、er,fossi1izedbitsandpiccesofanimalsabound,suggestingthatagreatburstofevolutionarycreativityoccurredinthe50-millionyearinterval.Thissurgeofnew1ife,markedbyanabundanceofanimals,isca1ledtheCambrianexp1osion.5. .Whichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepas

23、sage.Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.TherearefewfossilsfromthePrecambrian,thoughmorekeepturningup.Mostevidenceofanimalsinthefossilrecordisindirectand1ittleofitisfromthePrecambrian.TunnelsinPrecambrianrocksthatmayhavebeenmadebywormsprovideindirectevidence

24、oftheseanimalsexistingatthattime.ThereareveryfewfossilsofanimalsfromthePrecambrianandmostevidenceofanimal1ifefromthatperiodisindirect.6. Accordingtoparagraph3,theCambrianperiodwascharacterizedbyAgreatabundanceofanimalsAslowrateofanimalextinctionTherapidfossi1izationofanimalsAnincreaseinthelifespanof

25、someanimalsParagraph4：Thefirstdirectevidencefortheearlyoriginofeyescomesfromfossilsthatareabout530millionyearsold,atimeshort1yaftertheCambrianexp1osion;theywerefoundonamountainsideinBritishColumbiainadepositknownastheBurgessSha1e.TheBurgessShalefossilsareextraordinarilyimportantbecauseamongthemarere

26、mainsofsoftbodiedcreatures,manyofthemlackingshellsandotherhardpartsthatfossilizeeasily.Consequently,theirpreservationis1ittleshortofmiraculous(asarethede1icatemethodsusedtoreconstructthree-dimensionalstructurefromtheseflattenedfossi1s),andtheyareoneofthefewknownrepositoriesofearlysoft-bodiedanimals.

27、7. Thephraselittleshortofmiracu1ousisclosestinmeaningToveryhighlyvaluedAmazingbecausealmostimpossibleCausingcontroversyA1mostbutnotquitecomplete8. Accordingtoparagraph4,allofthefollowingaretrueoftheBurgessShaleEXCEPT:Itsfossi1swereinaf1attenedconditionwhendiscovered.Itsfossilsprovidedirectevideneeab

28、outtheoriginofeyes.ItcontainsfossilsofbothPrecambrianandCambriananima1s.Itcontainsfossilizedremainsofsoft-bodiedorganisms.Paragraph5:NotalloftheBurgessanimalshadeyes.However,somedid.(Grossfeatureslocation,size,andhemisphericshapeareresponsibleforthedesignationofsomestructuresaseyes).Thereconstructed

29、eyesoftheseBurgessanima1slooksuperficia1lylikeeyesofsomelivingcrustaceans,particularlythoseofshrimpandcrabswhoseeyesaremountedonstalksthatimprovetherangeofvisionbyraisingtheeyesabovethesurfaceofthehead.TheeyesofsomeBurgessorganismssatonstalks;thoseofotherswereonorapartofthebodysurface.Oneanimal,Opab

30、inia,hadfiveeyes:twolateralpairsandasinglemedialeye;atleastoneofthe1ateralpairshadstalksthatcou1dhavebeenmovab1e.Andsometrilobitelikeanima1sintheBurgessShalehadfacetedeyesmuchlikethoseoflaterfossiltrilobites.9. Theworddesignationinthepassageisc1osestinmeaningtoEvolutionIdentificationReconstructionCo

31、nfusion10. Thewordlateralinthepassageindicatesa1ocationattheFrontBackTopSide11. WhydoestheauthorpointoutthatTheeyesofsomeBurgessorganismssatonstalks?TosuggestthatsomeBurgessorganismshadagreaterrangeofvisionthandolivingshrimpandcrabsToexplainwhyitisthoughtthatoneofthelateralpairsofeyesinOpabiniamayha

32、vebeenmovableToexplainwhytheeyesofsomeBurgessanimalswerenotrecognizableassuchbeforetheywerereconstructedTosupportthestatementthatthereconstructedeyesofBurgessanimals100ksuperficiallyliketheeyesofsomelivingcrustaceansParagraph6:AlthoughthepresenceofeyesonsomeoftheBurgessanimalsindicatesthateyeshavebe

33、enaroundforaverylongtime,itisunlikelythatthesewerethefirsteyes;theysecmmuchtoolargeand(potentially)welldevelopedtobebrandnewinventions.ThebestwecandoisputtheoriginofeyessomewherebetweenthebeginningoftheCambrianexplosion,about600mi1lionyearsago,andthedeathoftheBurgessanimals,some530mi1lionyearsago.1

34、2.Paragraph6suggeststhatthefirsteyesprobablyCameintoexistencelongbefore600millionyearsagoCameintoexistenceatalatepointintheCambrianperiodExistedbeforetheanima1softheBurgessShaleexistedWerelargerthanthoseofanima1sfoundintheBurgessShaleParagraph1:Puttingadateonthefirstappearanceofeyesdependsonwhatonem

35、eansbyeye.Ifthetermreferstoamultice1lularorgan,evenifithasjustafewce1ls,thenbydefinition,eyescouldnotformbeforethereweremulticel1ularanimals.Butmanyprotists(animal-like,plantlike,orfungus-likeunice1lularorganismsthatrequireawater1. asedenvironment)candetectlightbyusingaggregationsofpigmentmolecules,

36、andtheyusethisinformationtomodifytheirmetabolicactivityormotility(theabilitytomovespontaneous1yandindependently).HOneofthefamiliarlivingexamples,probablyknowntoanyonewhohastakenabiologyclass,istheaquaticprotozoanEug1ena,whichhasaneyespotnearitsmoti1efIagellum(hairlikestructure).BSomelivingprotistsar

37、everyliketheirancestra1formsembeddedinancientsedimentaryrocks,andthissimilaritysuggeststhattheabilitytodetectlightandmodifybehaviorinresponsetolighthasbeenaroundforaverylongtime.0nimalsarosefromoneofsuchunicellularcreatures,perhapsfromonealreadyspecializedforaprimitivekindofvision.13. Lookatthefours

38、quaresthatindicatewherethefo1lowingsentencecou1dbeaddedtothepassage.Mo1ariaspiniferaandH.Optata,bothofwhichlivedinwaterlevelsbeyondthereachof1ight,fitintothiscategory.14. Directions:Anintroductorysentenceforabriefsummaryofthepassageisprovidedbelow.CompletethesummarybyselectingtheTHREEanswerchoicesth

39、atexpressthemostimportantideasinthepassage.Somesentencesdonotbelonginthesummarybecausctheyexpressideasthatarenotpresentedinthepassageorareminorideasinthepassage.Thisquestionisworth2points.Dragyourchoicestothespaceswheretheybelong.Toreviewthepassage,clickonViewText.AnswerChoicesTheabilityofsomeunicel

40、lularorganismstodetectlightandchangetheirbehavioraccordinglysuggeststhateyesdidnotoriginatewithmulticellularanimals.Theearliesteyesapparentlycontainedmoleculesthatwerecapab1eofformingandfocusingimages.ToofewfossilsfromthePrecambrianhavebeenfoundtodeterminewhichifanyPrecambrianorganismshadeyes.Eviden

41、cefromtheBurgessSha1esuggeststhateyesofsomeearlyanimalsweresimi1artotheeyesoflivingcrustaceans.FossilevidencesuggeststhatorganismsintheBurgessSha1ewithfacetedeyesdevelopedlaterthanorganismsintheBurgessShalewithnonfacetedeyes.ThelargesizeandpossiblecomplexityoftheeyesofsomeorganismsintheBurgessShales

42、uggestthattheireyeswerenotthefirsteyes.TPO36-2TheoriginofEarth'smtosphereInordertounderstandtheoriginofEarth'satmosphere,wemustgobacktotheearliestdaysoftheso1arsystem,beforetheplanetsthemselveswereformedfromadiskofrockymaterialspinningaroundtheyoungSun.Thismaterialgradual1ycoalescedintolumps

43、calledplanetesimalsasgravityandchancesmashedsmallerpiecestogether,achaoticandviolentprocessthatbecamemoresoasplanetesimalsgrewinsizeandgravitationa1pull.Withineach0rbit,col1isionsbetweenplanetesimalsgeneratedimmenseheatandenergy.Howviolenttheseprocesseswereissuggestedbytheoddti1tandspinofmanyofthepl

44、anets,whichindicatethateachoftheplanetswas,1ikeabil1iardba1l,struckatsomestagebyanotherlargebodyofsomekind.VisualevidenceoftheseprocessescanbeseenbylookingattheMoon.BecausetheMoonhasnoatmosphere,itssurfaceisnotsubjecttoerosion,soitretainsthemarksofitsear1yhistory.Itsfaceisdeeplyscarredbymillionsofme

45、teoricimpacts,asyoucanseeonac1earnightwithapairofbinoculars.Theear1yEarthdidnothavemuchofanatmosphere.Beforeitgrewtoful1size,itsgravitationalpullwasinsufficienttopreventgasesfromdriftingoffintospace,whilethesolarwind(thegreatstreamofatomicparticlesemittedfromtheSun)hadalreadydrivenawaymuchofthegaseo

46、usmateria1fromtheinnerorbitsofthesolarsystem.Sowemustimaginetheear1yEarthasamixtureofrockymateria1s,metals,andtrappedgases,subjecttoconstantbombardmentbysmallerplanetesimalsandwithoutmuchofanatmosphere.Asitbegantoreachfullsize,Earthheatedup,partlybecauseofcollisionswithotherplanetesimalsandpartlybec

47、auseofincreasinginternalpressuresasitgrewinsize.Inaddition,theearlyEarthcontainedabundantradioactivematerials,alsoasourceofheat.AsEarthheatedup,itsinteriorme1ted.Withinthemo1teninterior,undertheinfluenceofgravity,differentelementsweresortedoutbydensity.Byabout40millionyearsaftertheformationofthesola

48、rsystem,mostoftheheaviermeta11icelementsintheear1yEarth,suchasironandnickel,hadsunkthroughthehotsludgetothecentergivingEarthacoredominatedbyiron.ThismetalliccoregivesEarthitscharacteristicmagneticfield,whichhasplayedanextremelyimportantroleinthehistoryofourplanet.Asheavymaterialsheadedforthecenterof

49、Earth,lightersilicates(suchasthemineralquartz)driftedupward.ThedensersilicatesformedEarth'smantle,aregionalmost3,000kilometersthickbetweenthecoreandthecrust.Withthehelpofbombardmentbycomets,whosemanyimpactsscarredandheatedEarth'ssurface,thelightestsilicatesrosetoEarth'ssurface,wheretheyc

50、ooledmorerapidlythanthebetterinsulatedmaterialsinEarth'sinterior.Theselightermaterials,suehastherockswecallgranites,formedalayerofcontinentalcrustabout35kilometersthick.RelativetoEarthasawhole,thisisasthinasaneggshe1l.Seafloorcrustiseventhinner,atabout7kilometers;thus,evencontinentalcrustreach&#

51、169;sonlyabout1/200thofthewaytoEarth'score.MuchoftheearlycontinentalcrusthasremainedonEarth'ssurfacetothepresentday.Thelightestmateria1sofa1l,includinggasessuchashydrogenandhe1ium,bubbledthroughEarth'sinteriortothesurface.SowecanimaginethesurfaceoftheearlyEarthasamassivevolcanicfield.And

52、wecanjudgeprettywellwhatgasesbubbleduptothatsurfacebyanalyzingthemixtureofgasesemittedbyvolcanoes.Theseincludehydrogen,helium,methane,watervapor,nitrogen,ammonia,andhydrogensulfide.Othermaterials,inc1udinglargeamountsofwatervapor,werebroughtinbycometarybombardments.Muchofthehydrogenandheliumescaped;

53、butonceEarthwasfullyformed,itwaslargeenoughforitsgravitationa1fieldtoholdmostoftheremaininggases,andtheseformedEarth'sfirststableatmosphere.Paragraph1:InordertounderstandtheoriginofEarth'satmosphere,wemustgobacktotheearliestdaysoftheso1arsystem,beforetheplanetsthemselveswereformedfromadiskof

54、rockymaterialspinningaroundtheyoungSun.Thismaterialgradua11ycoalescedinto1umpscalledp1anetesima1sasgravityandchancesmashedsmallerpiecestogether,achaoticandviolentprocessthatbecamemoresoasplanetesimalsgrewinsizeandgravitationalpull.Withineach0rbit,collisionsbetweenplanetesima1sgeneratedimmenseheatand

55、energy.Howviolenttheseprocesseswereissuggestedbytheoddtiltandspinofmanyofthep1anets,whichindicatethateachoftheplanetswas,likeabi11iardbal1,struckatsomestagebyanotherlargebodyofsomekind.Visua1evidenceoftheseprocessescanbeseenbylookingattheMoon.BecausetheMoonhasnoatmosphere,itssurfaceisnotsubjecttoero

56、sion,soitretainsthemarksofitsearlyhistory.Itsfaceisdeeplyscarredbymi1lions0fmeteoricimpacts,asyoucanseeonaclearnightwithapairofbinocu1ars.Theear1yEarthdidnothavemuchofanatmosphere.Beforeitgrewtofu11size,itsgravitationa1pullwasinsufficienttopreventgasesfromdriftingoffintospace,whiletheso1arwind(thegr

57、eatstreamofatomicparticlesemittedfromtheSun)hadalreadydrivenawaymuchofthegaseousmaterialfromtheinnerorbitsofthesolarsystem.SowemustimaginetheearlyEarthasamixtureofrockymateria1s,metals,andtrappedgases,subjecttoconstantbombardmentbysmallerplanetesimalsandwithoutmuchofanatmosphere.1. Thewordcoalescedi

58、nthepassageisclosestinmeaningtoCo1lidedJoinedChangedShrank2. ThewordchaoticinthepassageisclosestinmeaningtoRapidDisorganizedIntenseLonglasting3. Allofthefo1lowingaretrueoftheplanetesimalsmentionedinparagraph1EXCEPT:TheywereformedofrockymaterialspinningaroundtheearlySun.Theycollidedviolentlywitheachother.Theygraduallygrewinsize.Theylosttheiratmospheresastheywerehitbylargerbodies.4. ThewordretainsinthepassageisclosestinmeaningtoRevealsAcquiresHidesPreserves5. TheauthordiscussestheMooninparagraph1inordertoHelpexp1ain