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  3. The recent news of the successful cloning of an adult sheep — in which the sheep’s DNA was inserted into an unfertilized sheep e

The recent news of the successful cloning of an adult sheep — in which the sheep’s DNA was inserted into an unfertilized sheep e

admin2015-01-26  36
问题     The recent news of the successful cloning of an adult sheep — in which the sheep’s DNA was inserted into an unfertilized sheep egg to produce a lamb with identical DNA — has generated an outpouring of ethical concerns. These concerns are not about Dolly, the now famous sheep, nor even about the considerable impact cloning may have on the animal breeding industry, but rather about the possibility of cloning humans. For the most part, however, the ethical concerns being raised are exaggerated and misplaced, because they are based on erroneous views about what genes are and what they can do. The danger, therefore, lies not in the power of the technology, but in the misunderstanding of its significance.
    Producing a clone of a human being would not amount to creating a " carbon copy" — an automaton of the sort familiar from science fiction. It would be more like producing a delayed identical twin. And just as identical twins are two separate people — biologically, psychologically, morally and legally, though not genetically — so to embrace a belief in genetic determinism — the view that genes determine everything about us, and that environmental factors or the random events in human development are utterly insignificant. The overwhelming consensus among geneticists is that genetic determinism is false.
    As geneticists have come to understand the ways in which genes operate, they have also become aware of the myriad ways in which the environment affects their "expression". The genetic contribution to the simplest physical traits, such as height and hair color, is significantly mediated by environmental factors. And the genetic contribution to the traits we value most deeply, from intelligence to compassion, is conceded by even the most enthusiastic genetic researchers to be limited and indirect. Indeed, we need only appeal to our ordinary experience with identical twins — that they are different people despite their similarities — to appreciate that genetic determinism is false.
    Furthermore, because of the extra steps involved, cloning will probably always be riskier — that is, less likely to result in a live birth — that in vitro fertilization(IVF)and embryo transfer. For example, it took more than 275 attempts before the researchers were able to obtain a successful sheep clone. While cloning methods may improve, we should note tat even standard IVF techniques typically have success rate of less than 20 percent. So why would anyone go to the trouble of cloning?
What process resulted in the successful cloning of an adult sheep?
选项 A、In vitro fertilization.
B、Embryo transfer.
C、The insertion of a mature sheep’s DNA into an unfertilized egg.
D、The adoption of physical and genetic characteristics.
答案C
解析 事实细节题。文中首段提及将绵羊的DNA“inserted into an unfertilized egg”从而成功克隆出成年绵羊。选项C与此信息一致。故答案为C。
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