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。ABritish scientists have done something that many people thought was impossible:they created the first clone of an adult mammal(哺乳动物).The clone,named Dolly,is a seven-month-old sheep,grown from a cell of an adult female sheep.What is a clone?A clone is a copya genetic copy.Genes are the instructions for life.They tell a cell what to do and how to do it.Genes make each individual plant or animal different and unique.But a clone has the same genes as the original organism(生物体).Cloning is not new.Plants have been cloned for centuries.New plants are often grown from cutting from another plant.Also,plants like pineapples,strawberries and carnations(康乃馨)are sometimes cloned.One benefit of cloning is that we can make many copies of the best and healthiest plants.It has been much more difficult to clone animals.Frogs have been cloned,but they died as tadpoles,never living long enough to become adult frogs.Mice,sheep and cattle have been cloned from embryos(胚胎).But Dolly is the first healthy clone of an adult mammal.How did they do it?(1)An unfertilized egg was taken from a sheep.(2)The egg nucleus(细胞核)was removed.(3)A cell was taken from the udder(乳房) of a pregnant(怀孕的)sheep.It was “starved”,so that it stopped growing.(4)The two cells were combined into one and then implanted in a third sheep,where it grew normally.(5) The clone was born.It was genetically identical to the pregnant sheep in step (3).This sounds much easier than it actually was.To end up with one clone,the scientists started with 277 udder cells.And they needed in a way to make the egg cell accept a new nucleus.They did that by starving the cell in step (3).It may soon be possible to clone many types of animals.Will we also be able to clone human organs,or even whole human beings?We have only begun to think about the morality of cloning technology.Maybe the question to ask is not whether we can clone humans,but instead,should we clone humans?1Dolly is a sheep because she is grown from a cell of an adult female sheep.A.that has not her father B.that has not her motherC.that has no parentsD.that has not any tail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。2Which of the following statements is TRUE?A.Only plants can be cloned.B.Only strawberries and carnations can sometimes be cloned.C.Animals and plants have quite a long history of cloning.D.Genes can tell a cell what to do and how to do it during cloning.答案D解析细节理解题。D项“基因在克隆过程中可以告诉细胞做什么及如何去做”,文章第二段说的正是这个意思。第三段指植物可以克隆,第四段指动物也可以克隆,所以A项“只有植物可以克隆” 不正确。从文中第三段可知菠萝也是可以克隆的,所以B 项“只有草莓和康乃馨可以克隆”不正确。第三段中指植物已有几个世纪的克隆历史,而没有提到动物的克隆历史,所以C 项“动植物都有相当长的克隆历史”与题意不符。3From the fourth paragraph we can know that .A.a tadpole is the early stage of a grown-up frogB.a tadpole is a frog without a tailC.a tadpole is a kind of animalD.a tadpole is a clone of an adult mammal答案A解析推理判断题。文章第四段第二句中说:人们曾经克隆过青蛙,但在蝌蚪阶段就死了,并没有进入成年青蛙阶段,所以我们可以判断,蝌蚪是青蛙的早期形态,故A 项正确。4Which is the right order in the process of the clone of Dolly?a.Taking an unfertilized egg from an adult female sheep.b.Removing the eggs nucleus.c.Combining the two cells into one and then implanting it in a third sheep.d.Taking a cell from the udder of a pregnant sheep.A.a b c dB.c a b dC.a b d cD.d c b a答案C解析细节排序题。根据克隆的步骤(1)(4)可知应选C项。B(导学号58980010)Have you seen Jurassic Park?In this film,scientists use DNA kept for tens of millions of years to clone dinosaurs.They find trouble,however,when they realize that the cloned creatures are smarter and more dangerous than expected.Thats nothing more than a fiction.But could we really clone endangered animals?To date,the most successful attempt to do so was the cloning of a gaur(野牛),a rare ox-like animal from southeast Asia.Scientists used a cow to bring the cloned baby gaur,named Noah.Two days after birth,however,Noah died from a common bacterial infection.Other endangered species that may be cloned include the African bongo antelope(邦戈羚羊),the Sumatran tiger,the cheetah(猎豹),and the giant panda.Next,could we really clone extinct animals?In theory?Yes.To do this,you need a well-kept source of DNA from the extinct animals such as wool mammoth(毛象),Tasmanian tiger,or even dinosaur,and a closely related species,still living,which could serve as a surrogate mother.In reality?Probably not.On the one hand,its not likely that extinct animals DNA could survive undamaged for such a long time.Cloning extinct animals as wool mammoth,Tasmanian tiger,or dinosaur is much more difficult due to the lack of properly well-preserved DNA.On the other hand,for example,a gaur can have a cow as a surrogate mother,definitely not a monkey.But what about an extinct animal as unique as the panda?What species could possibly serve as a surrogate mother?Cloning presents many exciting possibilities.However,even if extinct