It's unlikely that we'll see a dodo，a flightless bird，walking this earth anytime again，according to Beth Shapiro，a evolutionary molecular biologist.
"When most people think about de-extinction，they're imagining cloning，" Shapiro said.Cloning，the approach that created Dolly，the sheep in 1996 and Elizabeth Ann，the black-footed ferret in 2020，creates an identical genetic copy of an individual by putting DNA from a living adult cell into an egg cell from which the nucleus （細(xì)胞核） has been removed.Adult cells contain all the DNA needed to develop into a living animal.Egg cells then use that DNA as a blueprint to turn themselves into many kinds of cells-skin，organs，blood and bones-the animal needs.
"But no living cells from dodos exist.Instead，" Shapiro said， "you'd have to start with a closely related animal's genome （基因組） and then change it into one similar to dodos." For example，mammoths （猛犸） are also extinct，but they were very closely related to modern Asian elephants，so researchers are attempting to bring mammoths back from extinction by creating a hybrid mammoth with some mammoth genes replacing part of the elephant genome in an elephant egg cell.However，there are likely millions of genetic differences between the genome of an Asian elephant and that of a mammoth according to Shapiro.
As for the dodo，its closest living relative is the Nicobar pigeon.Mammoths and Asian elephants are pretty closely related，whereas it had been more than 20 million years since the dodo and the Nicobar pigeon had any common ancestors.Genetic differences between the two bird species are therefore much greater，making it a formidable task to create a successful hybrid in the lab，Shapiro said.
Even if scientists manage to bring dodos back，the island where they once lived is a very different place nowadays，which make it impossible to reintroduce dodos without major intervention.
（1）What is Paragraph 2 mainly about？ BB
A．The special role of DNA．
B．The process of cloning.
C．The development of cloning.
D．The complexity of cloning.
（2）What does Shapiro want to show by the example of mammoths？ AA
A．Dodos are harder to bring back to life.
B．Their living cells are hard to preserve.
C．Cloning can be used to recreate extinct animals.
D．They share a similar genome with Asian elephants.
（3）What does the underlined word "formidable" mean in Paragraph 4？ CC
A．Urgent.
B．Possible.
C．Tough.
D．Different.
（4）What is Shapiro's attitude towards the rebirth of dodos？ DD
A．Favorable.
B．Intolerant.
C．Objective.
D．Negative.
【考點(diǎn)】新聞報(bào)道；自然科學(xué)研究成果．
【答案】B；A；C；D
【解答】
【點(diǎn)評(píng)】
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發(fā)布：2024/5/27 14:0:0組卷：10引用：5難度：0.2
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