Module 2 DNA the secret of life Period One Introduction 课件.ppt

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1、Currentlytherearesome20,000chemicalsinuse,butthescientistsonlyhavedetailedinformationonaround1,000ofthem.ToseetheadvantagesofGMfoodyouhaveonlytoconsidertherecentpressrevelationthattheaveragelettucereceiveselevenpesticideapplicationsbeforeitreachesthesupermarketshelf.Module2DNAthesecretoflifePer

2、iodOneIntroduction&ReadingandVocabulary课件话题美文欣赏I'msurechemicalsandtheirrolesindiseasewillbecomeabigissueinthenextcenturyasthepopulationofthedevelopedworldworriesincreasinglyaboutitshealth.ThereasonGMfoodwillnotgoawayisthatweneedathreefoldincreaseinfoodproductionbytheyear2050tokeeppacewiththewor

3、ld'spredictedpopulationgrowthtotenorelevenbillion.It'snotjustaquestionofmoremouthstofeedeither.Whatisoftenforgottenisthatalltheseextrapeoplewilltakeupspace,reducingtheoveralllandavailableforagriculture.Theworldhas800millionhungrypeople.Untilnow,foodsupplieshavebeenincreasedbyimprovedvarieties,p

4、esticidesandartificialfertilizers:thegreenrevolution.Nowwe'reontheedgeofanewrevolution:ageneticone.ItmaywellbethatinthelongtermitisthedevelopingworldthatbenefitsmostfromGMfoods.It'struethatforthenexttenyearsorsoGMcropsmaybetooexpensive.Butthelessonofpersonalcomputersisapplicablehere－oncethetech

5、nologyhasbeendevelopedformoneyspinningcrops,likemaize,soybeansandcotton,itwillfilterdownandbecomeaffordableforall.Thisdoesn'tmean,unfortunately,thatfamineswilldisappear,butseverityanddurationwillbehelpedbyanimprovedabilitytoproduceanddistributefood.Aswemoveintothisneweraofagriculturewe'reembark

6、ingonanexperiment.Butrememberthattheworldhasseenanumberofexperimentsbefore.Wehavebeenrefiningspeciesofwheatforseveralthousandyears.Geneticengineerslikemearenotdoinganythingasdramaticasmakingacabbageintoacauliflower,ashasbeendonebyplantbreedersinthepast.We'resimplytappingintothewholegenepool,rat

7、herthanconcentratingononespeciesatatime.1．Accordingtothepassage,wecanseethattheauthorhasa/anattitudetowardsGMfood.A．disappointedB．indifferentC．hopefulD．uncertainReadthepassageandchoosethebestanswer.2．Whichofthefollowingstatementsi