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1、第二单元检测(时间:90分钟 满分:120分)第一部分 阅读理解(共两节,满分40分)第一节(共12小题;每小题2.5分,满分30分)阅读下面短文,从每题所给的A、B、C和D四个选项中,选出最佳选项。ABritishscientistshavedonesomethingthatmanypeoplethoughtwasimpossible:theycreatedthefirstcloneofanadultmammal(哺乳动物).Theclone,namedDolly,isaseven-month-oldsheep,grownfromacellofanadultfemalesheep.W
2、hatisaclone?Acloneisacopy—ageneticcopy.Genesaretheinstructionsforlife.Theytellacellwhattodoandhowtodoit.Genesmakeeachindividualplantoranimaldifferentandunique.Butaclonehasthesamegenesastheoriginalorganism(生物体).Cloningisnotnew.Plantshavebeenclonedforcenturies.Newplantsareoftengrownfromcuttingfrom
3、anotherplant.Also,plantslikepineapples,strawberriesandcarnations(康乃馨)aresometimescloned.Onebenefitofcloningisthatwecanmakemanycopiesofthebestandhealthiestplants.Ithasbeenmuchmoredifficulttocloneanimals.Frogshavebeencloned,buttheydiedastadpoles,neverlivinglongenoughtobecomeadultfrogs.Mice,sheepan
4、dcattlehavebeenclonedfromembryos(胚胎).ButDollyisthefirsthealthycloneofanadultmammal.Howdidtheydoit?(1)Anunfertilizedeggwastakenfromasheep.(2)Theeggnucleus(细胞核)wasremoved.(3)Acellwastakenfromtheudder(乳房)ofapregnant(怀孕的)sheep.Itwas“starved”,sothatitstoppedgrowing.(4)Thetwocellswerecombinedintoonean
5、dthenimplantedinathirdsheep,whereitgrewnormally.(5)Theclonewasborn.Itwasgeneticallyidenticaltothepregnantsheepinstep(3).Thissoundsmucheasierthanitactuallywas.Toendupwithoneclone,thescientistsstartedwith277uddercells.Andtheyneededinawaytomaketheeggcellacceptanewnucleus.Theydidthatbystarvingthecel
6、linstep(3).Itmaysoonbepossibletoclonemanytypesofanimals.Willwealsobeabletoclonehumanorgans,orevenwholehumanbeings?Wehaveonlybeguntothinkaboutthemoralityofcloningtechnology.Maybethequestiontoaskisnotwhetherwecanclonehumans,butinstead,shouldweclonehumans?1Dollyisasheep becausesheisgrownfromacell
7、ofanadultfemalesheep. A.thathasnotherfather B.thathasnothermotherC.thathasnoparentsD.thathasnotanytail答案C解析推理判断题。从文中可以看出,多莉是从一只成年羊的细胞中克隆出来的,所以它没有父母,而是那只成年羊的一个翻版。2WhichofthefollowingstatementsisTRUE?A.Onlyplantscanbecloned.B.
