2024剑桥雅思讲义True_False_NG_Questions_Strategy_Practice.docx

IELTSADVANTAGETrue/False/NGQuestionsStrategyPracticeHowhumanmedicinecouldsavetheTasmaniandevilTransmissiblecancersareincrediblyrareinnature,yethaveariseninTasmaniandevils(atypicallydog-sizedmammalwhichlivesinthewildonlyontheAustralianislandofTasmania)onatleasttwoseparateoccasions.NewresearchfromtheUniversityofCambridgehasidentifiedkeyanti-cancerdrugswhichcouldbetrialledasatreatmentforthesediseases,whicharethreateningTasmaniandevilswithextinction.TheresearchalsofoundthatthetwoTasmaniandeviltransmissiblecancersareverysimilartoeachother,andlikelybotharoseduetosusceptibilitiesinherenttothedevilsthemselves.Tasmaniandevilsareconsideredendangeredduetodevilfacialtumour1(DFT1),acancerthatispassedbetweenanimalsthroughthetransferoflivingcancercellswhentheanimalsbiteeachother.DFT1causesgrotesqueanddisfiguringfacialtumourswhichusuallyMilaffectedindividuals.TheDFT1cancerfirstaroseinasingleindividualdevilseveraldecadesago,butratherthandyingtogetherwiththisdevil,thecancersurvivedby4metastasising,intodifferentdevils.Therefore,theDNAofthedevils,tumourcellsisnottheirownDNA,butratherbelongstotheindividualdevilthatfirstgaverisetoDFT1allthoseyearsago.Remarkably,DFT1cellscanescapethedevils*immunesystemsdespitebeinginessenceaforeignbody.TheDFT1cancerwasfirstobservedinnorth-eastTasmaniain1996,buthassubsequentlyspreadwidelythroughouttheisland,causingsignificantdeclinesindevilpopulations.In2014,routinediagnosticscreeningrevealedasecondtransmissiblecancerinTasmaniandevils,devilfacialtumour2(DFT2),whichcausesfacialtumoursindistinguishabletothenakedeyefromthosecausedbyDFT1,andwhichisprobablyalsospreadbybiting.However,analysisshowedthatthetwotypesofcancerdifferatabiologicallevel,andwhereasDFT1firstarosefromthecellsofafemaledevil,DFT2appearstohavefirstarisenfromamaleanimal.Fornow,DFT2appearstobeconfinedtoapeninsulainTasmania,ssouth-east.uThediscoveryofasecondtransmissiblecancerinTasmaniandevilswasahugesurprise,"saysDrElizabethMurchisonfromtheDepartmentofVeterinaryMedicineattheUniversityofCambridge.uOtherthanthesetwocancers,weknowofonlyoneothernaturallyoccurringtransmissiblecancerinmammals-thecaninetransmissiblevenerealtumourindogs,whichfirstemergedseveralthousandyearsago.Note:ThisisnotarealIELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuestionsStrategyPracticeInfact,outsideofmammals,onlyfivetransmissiblecancershavebeenobserved,allofwhichcauseIeukaemia-Iikediseasesinclamsandothershellfish.“Thescarcityoftransmissiblecancerssuggeststhatsuchdiseasesemergerarely,sheadds."Before1996,noonehadobservedtheminTasmaniandevils,sofindingtwotransmissiblecancersinTasmaniandevilsinjusteighteenyearswasverysurprising?Inordertoseewhetherthedeviltransmissiblecancersarecausedbyexternalfactorsorwhethertheanimalswerejustparticularlysusceptibletodevelopingthesecancers,aresearchteamledbyDrMurchisonanalysedthegeneticprofilesofDFT1andDFT2tumourstakenfromanumberofTasmaniandevils.Theteamfoundstrikingsimilaritiesintissues-of-origin,genetics,howthecancercellsmutate,andpossibledrugtargets.Thisimpliesthatthetwotumoursbelongtothesamecancertypeandaroseviasimilarmechanisms.Theteamstudiedthegeneticandphysicalfeaturesofthetumours,andcomparedthetwolineageswitheachotherandwithhumancancers.Indoingso,theyidentifiedanimportantroleinthetumoursforparticulartypesofmoleculesknownasreceptortyrosinekinases(RTKs)insustaininggrowthandsurvivalofDFTcancers.Importantly,drugstargetingRTKshavealreadybeendevelopedforhumancancer,andtheresearchersshowedthatthesedrugsefficientlystoppedthegrowthofdevilcancercellsgrowinginthelab.ThisleadstohopethatitmaybepossibletousethesedrugstohelpTasmaniandevils.WhyTasmaniandevilsshouldbeparticularlysusceptibletotheemergenceofDFTsisnotclear.However,devilsbiteeachotherfrequentlyaroundthefacialarea,oftencausingsignificanttissueinjury.GiventheimportantroleforRTKmoleculesinwoundhealing,theresearchersspeculatethatDFTcancersmayarisefromerrorsinthemaintenanceofproliferativecellsinvolvedintissuerepairafterinjury."Whenfighting,Tasmaniandevilsoftenbitetheiropponentsface,whichmaypredisposetheseanimalstotheemergenceofthisparticulartypeofcancerviatissueinjury,saysfirstauthorofthestudy,MaximilianStammnitz.uAsbitingoccursontheface,thiswouldsimultaneouslyprovidearouteofcelltransmission.,TheresearcherssayitisalsopossiblethathumanactivitiesmayhaveindirectlyincreasedtheriskoftheemergenceorspreadoftransmissibledevilfacialtumoursNote:ThisisnotarealIELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuestionsStrategyPractice(DFTs)inrecentyears.Forinstance,itispossiblethatsomemodernlandusepracticesmayhaveprovidedfavourableconditionsfordevils,leadingtoanincreaseinlocalpopulationdensitiesofdevils,andtogreatercompetition,interactionsand