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B
During the Ice Age, the mammoths(猛犸象) lived both in Asia and America. But by about 4,000 years ago, the large and hairy elephants had disappeared.
Some scientists want to clone a mammoth, and the first need is some mammoth DNA. Since the 1900s, scientists have been digging up remains(残骸) of mammoths in the cold ground. Some still even have their skin and hair. Unluckily, even when it’s frozen, DNA still can’t be kept very well. It starts to break apart soon after an animal dies. Scientists have found lots of mammoth DNA—but it’s all just short bits and in a mess.
Modern Asian elephants are cousins of the ancient mammoths. Their DNA is about 99% the same. Still, that adds up to 70 million differences. But if we could change the elephant’s DNA in the places that are different, could we make mammoth DNA? Some researchers at Harvard are giving it a try. They have got out 14 bits of DNA in elephant blood cells that help mammoths stand the cold. It seemed to work. But they’re only working with groups of cells, not a whole animal. There is still a long way to go before cloning a mammoth.
Even if scientists could clone a mammoth or other disappeared animals, would it be a good idea? It might be cool to see a real, living mammoth. But would such an animal be happy, with no other mammoths around? Who would teach it how to be a mammoth? There are important questions for trying to bring back any disappeared creature. Cloning is expensive and often fails. Would the money be better spent in saving endangered animals that are still alive?
(
A. It stayed the same.
B. It got longer.
C. It disappeared.
D. It broke apart.
(
A. The scientists are going to put the DNA of standing cold in another animal.
B. The scientists at Harvard have already cloned a mammoth very successfully.
C. It isn’t easy to clone a disappeared animal though their DNA is close to some animals.
D. There are lots of differences of DNA between mammoths and modern Asian elephants.
(
A. In a story magazine.
B. In a cartoon newspaper.
C. On a science website.
D. In a fashion report.
During the Ice Age, the mammoths(猛犸象) lived both in Asia and America. But by about 4,000 years ago, the large and hairy elephants had disappeared.
Some scientists want to clone a mammoth, and the first need is some mammoth DNA. Since the 1900s, scientists have been digging up remains(残骸) of mammoths in the cold ground. Some still even have their skin and hair. Unluckily, even when it’s frozen, DNA still can’t be kept very well. It starts to break apart soon after an animal dies. Scientists have found lots of mammoth DNA—but it’s all just short bits and in a mess.
Modern Asian elephants are cousins of the ancient mammoths. Their DNA is about 99% the same. Still, that adds up to 70 million differences. But if we could change the elephant’s DNA in the places that are different, could we make mammoth DNA? Some researchers at Harvard are giving it a try. They have got out 14 bits of DNA in elephant blood cells that help mammoths stand the cold. It seemed to work. But they’re only working with groups of cells, not a whole animal. There is still a long way to go before cloning a mammoth.
Even if scientists could clone a mammoth or other disappeared animals, would it be a good idea? It might be cool to see a real, living mammoth. But would such an animal be happy, with no other mammoths around? Who would teach it how to be a mammoth? There are important questions for trying to bring back any disappeared creature. Cloning is expensive and often fails. Would the money be better spent in saving endangered animals that are still alive?
(
D
) 5. What happened to mammoth DNA?A. It stayed the same.
B. It got longer.
C. It disappeared.
D. It broke apart.
(
C
) 6. What can we learn from the third paragraph?A. The scientists are going to put the DNA of standing cold in another animal.
B. The scientists at Harvard have already cloned a mammoth very successfully.
C. It isn’t easy to clone a disappeared animal though their DNA is close to some animals.
D. There are lots of differences of DNA between mammoths and modern Asian elephants.
(
C
) 7. Where can we most probably read this passage?A. In a story magazine.
B. In a cartoon newspaper.
C. On a science website.
D. In a fashion report.
答案
5. D 6. C 7. C
解析
【分析】
第5题需定位原文中关于猛犸DNA状态的描述，匹配选项；第6题需理解第三段整体内容，分析各选项与原文的契合度；第7题需根据文章内容判断体裁，选择合适出处。
【解析】
5. 定位原文第二段：“even when it’s frozen, DNA still can’t be kept very well. It starts to break apart soon after an animal dies.” 可知猛犸象死后DNA会分解，对应选项D。A、B、C均与原文不符，故选D。
6. 分析第三段：哈佛团队仅在细胞层面研究，未克隆出完整动物，说明克隆灭绝动物虽DNA接近但难度大。A选项原文未提及；B选项“已成功克隆”与原文矛盾；D选项非第三段核心内容，故选C。
7. 文章围绕克隆猛犸象的科学话题展开，属于科普类内容，最可能出现在科学网站，A、B、D均不符合，故选C。
【答案】5.D 6.C 7.C
【知识点】英语阅读理解、细节理解、推理判断
【点评】本文是科普类英语阅读理解，考查学生细节定位、段落主旨理解及体裁判断能力，需仔细比对原文与选项，规避干扰项。
【难度系数】0.5
第5题需定位原文中关于猛犸DNA状态的描述，匹配选项；第6题需理解第三段整体内容，分析各选项与原文的契合度；第7题需根据文章内容判断体裁，选择合适出处。
【解析】
5. 定位原文第二段：“even when it’s frozen, DNA still can’t be kept very well. It starts to break apart soon after an animal dies.” 可知猛犸象死后DNA会分解，对应选项D。A、B、C均与原文不符，故选D。
6. 分析第三段：哈佛团队仅在细胞层面研究，未克隆出完整动物，说明克隆灭绝动物虽DNA接近但难度大。A选项原文未提及；B选项“已成功克隆”与原文矛盾；D选项非第三段核心内容，故选C。
7. 文章围绕克隆猛犸象的科学话题展开，属于科普类内容，最可能出现在科学网站，A、B、D均不符合，故选C。
【答案】5.D 6.C 7.C
【知识点】英语阅读理解、细节理解、推理判断
【点评】本文是科普类英语阅读理解，考查学生细节定位、段落主旨理解及体裁判断能力，需仔细比对原文与选项，规避干扰项。
【难度系数】0.5
