资源描述：
《people have been wondering why elephants do not develop阅读理解答案》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。
1、Peoplehavebeenwonderingwhyelephantsdonotdevelop阅读理解答案 Peoplehavebeenwonderingwhyelephantsdonotdevelopcancereventhoughtheyhavelifespans（寿命）thataresimilartohumans,livingforaround50to70years. Nowscientistsbelievetheyknowwhy.AteamattheUniversityofChicago,UShasfoundthatelephantsca
2、rryalargenumberofgenesthatstoptumors（肿瘤）developing.Tobeprecise,theyfound20copiesofananti-tumorgenecalledTP53inelephants.Mostotherspecies,includinghumans,onlycarryonecopy. Accordingtotheresearch,theextracopiesofthegeneimprovedtheanimal’ssensitivitytoDNAdamage,whichletsthecellsq
3、uicklykillthemselveswhendamagedbeforetheycangoontoformdeadlytumors. “Anincreasedriskofdevelopingcancerhasstoodinthewayoftheevolutionoflargebodysizesinmanyanimals,”thestudyauthorDrVincentLynchtoldTheGuardian.Ifeverylivingcellhasthesamechanceofbecomingcancerous（癌变的）,largecreatur
4、eswithalonglifespanlikewhalesandelephantsshould haveagreaterriskofdevelopingcancerthanhumansandmice.Butacrossspecies,theriskofcancerdoesnotshowaconnectionwithbodymass. ThisphenomenonwasfoundbyOxfordUniversityscientistRichardPetointhe1970sandlaternamed“Peto’sparadox（悖论）”.Bio
5、logistsbelieveitresultsfromlargeranimalsusingprotectionthatmanysmalleranimalsdonot.Intheelephant’scase,themakingofTP53isnature’swayofkeepingthisspeciesalive. Thestudyalsofoundthatwhenthesamegeneswerebroughttolifeinmice,theyhadthesamecancerresistanceaselephants.Thismeansresearc
6、herscouldusethediscoverytodevelopnewtreatmentsthatcanhelpstopcancersspreadingorevendevelopinginthefirstplace. “Naturehasalreadyfiguredouthowtopreventcancer,”saidJoshuaSchiffman,abiologistattheSchoolofMedicine,UniversityofUtah,US.“It’suptoustolearnhowdifferentanimalsdealwiththe
7、problemsothatwecanusethosestrategiestopre ventcancerinpeople.” 32.Whyareelephantsunlikelytodevelopcancer? A.Theyhavearatherlargebodysize. B.TheirgenessuffernoDNAdamage. C.Certaingenesintheirbodykillexistingtumors. D.Theycarrymanygenestopreventtumorsdeveloping. 33.Accor
8、dingtothepassage,whathasbeenariskintheevolutionoflarge
