英语第8册第2单元VIP免费

Unit2CloningSectionⅠWarmingUp&Reading—Pre-reading1．Whataretheadvantagesanddisadvantagesofcloning?2．Notonlyanimalsbotalsoplantscanbecloned．Doyouknowthedifferencebetweenthem?Pleasereadthefollowingpassagetogettheanswer．Anewstudyofplantsthatarereproducedhycloninghasshownwhyclonedplantsarenotldentlcal.Scientistshaveknownorsorfletimethatclonedorganismserenotalwaysidcntical：theirobservablecharacteristicsandtraitscanvary，andthisvariationcanbepassedontotileiicxtgeneration．Thisisdcspirethefactthattheyatederived(获得)fromgenedcallyidenticalfoundercells.Now，ateamfromOxfordUniversity，theUK．andKingAbdu№hUniversityofScienceandTechnology，SaudiArabia，believetheyhavefoundoutwhythisisthecaseinplants：thegenomes(染色体)ofregenerateplantscarryrelativelyhighfrequenciesofnewDNAsequencemutations(变异)thatwerenotpresentinthegenuineofthedonorplant．Theteamreportedtheirfindingsinthisweek’sCurrentBiology.“Wherethesenewmutationsactuallycoomfromisstillamystery，”saidProfessorHarberd.“TheymayariseduringtheregenerationprocessitselforduringthecelldivisionsinthedonorplantthatgaverisetotherootceilsfromwhichtheregenerateplantsarecreatedWeareplanrlingfurtherresearchtofindoutwhichofthesetwoprocessesisresponsibleforthesemutations.WhatwecanSaylsthatnaturehassafelybeenemployingwhatyoumightcalla‘cloning’processinplantsfoTmillionsofyears，andthattheremustbcgoodevolutionaryreasollswhythesemutatlonsareintroduced．”Thenewresultssuggestthatvariationinclonesofplantsmayhavediffcrentunderlyingcausesfromthoseofvariationincloncsofanlmalswhereitisbelievedthattheeffectofenvironmerltalfactorsonhowanimalgenesareexpressedisnloreimportantandnosimilarhighfrequenciesofmutationshavebeenobserved．ProfessorHarberdsaid，“WhileourrcstlltShighlightthatclonedplantsaadanimalsareverydifferent，theymaygiveusinsightsintohowbacterialandcancercellsrcplicatethcmselves，andhowmuutationsariseduringtheseprocesseswhich，ultimately，haveanimpactonhumanhealth．”Step1WarmingUp1．Howmuchdoyouknowaboutclone?Whatisclone?Andwhatarenaturalcloneandman—madeclone?2．Lookatthesepicturesandtellwhichonesarenatu一ralclonesandwhichonesareman—made.3．Seeanotherkindofclone．Thetwowomensoldierslookveryalike．Canyouexplainwhy?Step2FastReading11．Readthetextandwritedownthemainideaofthetext．ThetextismainlyabouttheofanimalcIoningandthelifeofDollythesheep，aswellasthereasonswhycloningisstill．2．Readthetextandthenfindthemainideaofeachparagraph．Paragraph1()a．TheeffectofDolly．Paragraph2()b．Themajorusesofcloning．Paragraph3()C．People’Sreactiontocloning．Paragraph4()d．Thedefinition(定义)ofcloning．Paragraph5()e．TheproblemofDolly．Step3．CarefulReadingReadthetextandthenchoosethebestansweraccordingtothetext．(1)WhichofthefollowingstalementsaboutcloningisNOTtrueaccordingtothetext?A．Cloningissomethingthathasbeendevelopedquiterecently．B．Twinsthatlookexactlythesameareoriginallyfromthesameegg．C．Cloningisusedbygardenerstomakemoremonev．D．Animalcloningismuchmoredifficultthanplantclonlng.(2)ThecloningofDollythesheepsucceededbecauseA．it’SeasiertocloneasheepthanotheranimalsB．thescientistsweredeterminedandWOrkedhardwithpatienceC．thescientistswererewardedandgotlotsofmoneyD．manyotherattemptstoclonemammalsfailed(3)Thesheepthatdonatedthesomaticcellmostprobablvlivedyears．A．3B．6C．9D．12(4)WhichofthefollowingisNOTanadvantageofcloning?A．Cloning...