新视野视听说教程听力稿及答案(第四册)第8单元

Uint8II.BasicListeningPractice1.ScriptM:Scentistsclaimtheworldpopulationhas99.5%ofthesameDNA.W:Butthisdoesn’ttellusthereisnosuchthingasrace.Q:WhatistrueoftheDNAofdifferenceraces?2.ScriptW:Withtheadventofthegeneticmapweknowwhereeverythingis,butdoweknowwheretogowithit?M:Yourmapseemstodifferlargelyfrommygeographicalmap!Q:Whatdoesthemanimply?3.ScriptM:Asyouknow,ithastakenmillionsofyearsofevolutionandnaturalselectiontogetuswherewearetoday.W:Yes,butnowthatwehavegeneticengineering,weseemtohavedecidedthatwewanttobeGod.Q:Whatdoesthewomanimply?4.ScriptM:Ithinktheresearchintocloningwillleadusintodangers,fillinguswithfalsehopesofperfection.W:It’stoolatetoturnbacktheclock.We’lljusthavetodependoncommonsensetosolveuncommonproblems.Q:Whatdoesthewomanmean?5.ScriptW:InAmerica,manyprisonersarehavingtheircasesreviewed,andsomehaveevenbeenfreedthroughDNAtesting.M:Exceptfortheoneswhosedeathsentencehasalreadybeencarriedout.Q:WhatcanwelearnaboutDNAtestingfromthedialog?Keys:1.B2.C3.D4.A5.CIII.ListeningInTask1:StemCellResearchScriptGregory:TheRepublicanpartyinAmericaisopposingstemcellresearch.Ifindithardtobelievethatinthisdayandage,someonewoulddothat.Lillian:Stemcellresearchsoundsprettyimpressive,I’lladmit.Butjustwhatisit?Gregory:Well,astemcellisaspecialtypeofcell.Itisageneralcellthat,whenitdevides,canbecomeanyspecifictypeofcell.Lillian:Youmean,astemcellcanbecomeaheartcell?Orabrainorakidneycell?Gregory:That’saboutit.Stemcellsareapartofthebody’smaintenanceandrepairsystem.Whentheydivide,theycanbecomeanycelltype.Lillian:Iguesstherewouldbesometremendousmedicaladvantagesinthatsortofresearch.Gregory:You’vesaidamouthful.Recently,scientistswereabletohelpamanwholostajawboneforcancer.Theyrecreatedbonematerialforhisjawfromstemcells.Whatitmeansisthatsincethenewbonewascreatedoutoftheperson’sowncells,therewasnoproblemwithrejectionbecausetheDNAwasthesame.Lillian:Ibetthepersonwasdelighted.Whywouldanyoneopposethatsortofresearch?Itwouldseemtohaveendlesspotentialtobenefitthehumanrace.Gregory:Iagree,buttherearepeoplewhothinkweshouldnotinterferewithnatureandmanipulate“whatisnatural”.Lillian:It’seasiertoholdsuchanarrowviewifyou’renotinapositiontoneedthebenefitsoftheresearch.Ifyou’remissingajawbonebecauseofcancer,youprobablysupporttheresearch.1.Whatisthepassagemainlyabout?2.Whoisagainststemcellresearch?3.Whatisspecialaboutastemcell?4.Whencanastemcellbecomeanothercelltype?5.Accordingtothepassage,whydosomepeopleopposestemcellresearch?Keys:1.B2.A3.A4.A5.DTask2:TheImprovementofRiceScriptScientistsnowknowalotmoreaboutagrainthatpeoplehaveeatenfortenthousandyears.(S1)Researchteamsaroundtheworldhavecompletedamapofthe(S2)genesofrices.Thefindingsappearedlastweekinthe(S3)journalNature.Theaimistospeeduptheimprovementofrice.Thescientists(S4)warnthatthekindsofriceplantsusednowhavereachedthelimitoftheir(S5)productivity.Yetworldriceproductionmust(S6)growbyanestimated30percentinthenexttwentytomeetdemand.By2025,asmanyas4.6billionpeoplewilldependonricefor(S7)survival.Thereisalotofpressureonbreederstoimprovethecrop,andthericegenomeisavaluabletooltodothat.(S8)Plantbreedershavealreadyusedpreliminaryinformationfromthericegenometocreateexperimentalstrainsofricethatbetterresistcoldandpests.Theresearchersalsosayriceisanexcellentchoiceforgeneticmappingandengineering.Ricegeneshaveonlyabout390millionchemicalbases.Thatmaightsoundlikealot.Butothermajorfoodgrainshavethousandsofmillions.(S9)Thenewmapcouldbetterexplainmorethanjustrice.Ricesharesacommonancestorwithothercerealcrops.Becausericeisthefirstcerealcroptobefullyanalyzed,researchersexpectthatsufficientknowledgeofitsgeneticinformationwillrevealtheheredityofmorecomplexgrains,includingcorn,wheatandbarley.(S10)Whilesignificantprogresshasbeenmadeintheanalysisofthericegenome,themappingofhumangenesisalsomakingheadway.Whenscientistscanidentifyandmanipulategenesthatcausecertaindiseases,mankindwillcurethemeasily.Thehumangeneticmapmayhelpuscontrolaperson’sheight,weight,appearanceandevenlengthoflife.Task3:TheFirstClonedCatScriptIntheage-oldbattleofcatsanddogs,scoreoneforthecats.ResearchersatTexasA&MUniversityrecentlyannouncedthattheyhavesuccessfullyclonedacatnameRainbow—thefirstpetevercloned—afterseveralyearsofunsuccessfuleffortstocloneadognameMissy.Theork,financedbyacompanyhopingtoprovidepet-cloningservicestowealthyowners,addscatstoagrowinglistofsuccessfullyclonedanimalsthatincludespigs,sheep,cattleandmice.Thesuccessdemonstratescloningisatechnologythatcouldbetransferredtootheranimalfamiliesaswell.Theaccomplishmentmayprovidenewtoolsforstudyingdiseasessuchascats’AIDS,avaluableresearchmodelforAIDSinhumans.Researchintoanimalcloningremainsanimportantscientificalternativeuntiltheissueofhumancloningissettled.Andthatseemsunliklyintheimmediatefuture,foritinvolvesreligiousandmoralprinciples.Thereare,forexample,groupsthatinsistnooneshouldbeallowedtotakeontheroleofGodtheCreator.Tocreateclonedcatembryosfortheexperiment,researcherstransferredDNAfromadultcatcellsintoeggcellsstrippedoftheirowngeneticinformation.Outof82attemptswithclonedembryos,oneattemptresul