精品学习网收集整理了，2013年考研英语阅读理解经典练习（生物学类），希望对大家有所帮助！

SAMPLE2

[生物学类]

Thefossilremainsofthefirstflyingvertebrates,thepterosaurs,haveintriguedpaleontologistsformorethantwocenturies.Howsuchlargecreatures,whichweighedinsomecasesasmuchasapilotedhang-gliderandhadwingspansfrom8to12meters,solvedtheproblemsofpoweredflight,andexactlywhatthesecreatureswere—reptilesorbirds—areamongthequestionsscientistshavepuzzledover.

Perhapstheleastcontroversialassertionaboutthepterosaursisthattheywerereptiles.Theirskulls,pelvises,andhindfeetarereptilian.Theanatomyoftheirwingssuggeststhattheydidnotevolveintotheclassofbirds.Inpterosaursagreatlyelongatedfourthfingerofeachforelimbsupportedawinglikemembrane.Theotherfingerswereshortandreptilian,withsharpclaws.Inbirdsthesecondfingeristheprincipalstrutofthewing,whichconsistsprimarilyoffeathers.Ifthepterosaurswalkedonallfours,thethreeshortfingersmayhavebeenemployedforgrasping.Whenapterosaurwalkedorremainedstationary,thefourthfinger,andwithitthewing,couldonlyturnupwardinanextendedinvertedVshapealongeachsideoftheanimal’sbody.

Thepterosaursresembledbothbirdsandbatsintheiroverallstructureandproportions.Thisisnotsurprisingbecausethedesignofanyflyingvertebrateissubjecttoaerodynamicconstraints.Boththepterosaursandthebirdshavehollowbones,afeaturethatrepresentsasavingsinweight.Inthebirds,however,thesebonesarereinforcedmoremassivelybyinternalstruts.

Althoughscalestypicallycoverreptiles,thepterosaursprobablyhadhairycoats.T.H.Huxleyreasonedthatflyingvertebratesmusthavebeenwarm-bloodedbecauseflyingimpliesahighrateofmetabolism,whichinturnimpliesahighinternaltemperature.Huxleyspeculatedthatacoatofhairwouldinsulateagainstlossofbodyheatandmightstreamlinethebodytoreducedraginflight.Therecentdiscoveryofapterosaurspecimencoveredinlong,dense,andrelativelythickhairlikefossilmaterialwasthefirstclearevidencethathisreasoningwascorrect.

Effortstoexplainhowthepterosaursbecameairbornehaveledtosuggestionsthattheylaunchedthemselvesbyjumpingfromcliffs,bydroppingfromtrees,orevenbyrisingintolightwindsfromthecrestsofwaves.Eachhypothesishasitsdifficulties.Thefirstwronglyassumesthatthepterosaurs’hindfeetresembledabat’sandcouldserveashooksbywhichtheanimalcouldhanginpreparationforflight.Thesecondhypothesisseemsunlikelybecauselargepterosaurscouldnothavelandedintreeswithoutdamagingtheirwings.Thethirdcallsforhighwavestochannelupdrafts.Thewindthatmadesuchwaveshowever,mighthavebeentoostrongforthepterosaurstocontroltheirflightonceairborne.

1.Itcanbeinferredfromthetextthatscientistnowgenerallyagreethatthe

[A]enormouswingspanofthepterosaursenabledthemtoflygreatdistances.

[B]structureoftheskeletonofthepterosaurssuggestsacloseevolutionaryrelationshiptobats.

[C]fossilremainsofthepterosaursrevealhowtheysolvedtheproblemofpoweredflight.

[D]pterosaurswerereptiles.

2.Theauthorviewstheideathatthepterosaursbecameairbornebyrisingintolightwindscreatedbywavesas

[A]revolutionary.

[B]unlikely.

[C]unassailable.

[D]probable.

3.Accordingtothetext,theskeletonofapterosaurcanbedistinguishedfromthatofabirdbythe

[A]sizeofitswingspan.

[B]presenceofhollowspacesinitsbones.

[C]anatomicoriginofitswingstrut.

[D]presenceofhooklikeprojectionsonitshindfeet.

4.TheideasattributedtoT.H.Huxleyinthetextsuggestthathewouldmostlikelyagreewithwhichofthefollowingstatements?

[A]Ananimal’sbrainsizehaslittlebearingonitsabilitytomastercomplexbehaviors.

[B]Ananimal’sappearanceisofteninfluencedbyenvironmentalrequirementsandphysicalcapabilities.

[C]Animalswithinagivenfamilygroupareunlikelytochangetheirappearancedramaticallyoveraperiodoftime.

[D]Theoriginofflightinvertebrateswasanaccidentaldevelopmentratherthantheoutcomeofspecializationoradaptation.

5.Whichofthefollowingbestdescribestheorganizationofthelastparagraphofthetext?

[A]Newevidenceisintroducedtosupportatraditionalpointofview.

[B]Threeexplanationsforaphenomenonarepresentedandeachisdisputedbymeansofspecificinformation.

[C]Threehypothesesareoutlinedandevidencesupportingeachisgiven.

[D]Recentdiscoveriesaredescribedandtheirimplicationsforfuturestudyareprojected.

.