20.The science behind cloning
Since Dolly the sheep was cloned by Scottish scientists in 1997,cloning has been talked about all over the world.However,many people still do not fully understand cloning.This article describes what cloning is and what it means for people around the world.
There are three types of cloning,DNA cloning,reproductive cloning and therapeutic cloning.DNA cloning had been conducted by scientists since the 1970s.It involves taking one part of a person's or an animal's DNA-a single gene-and placing it where it can reproduce itself many times on its own.This type of cloning has helped scientists produce body parts and organs in laboratories.Reproductive cloning is creating a person or an animal that is genetically exactly the same as another.Therapeutic cloning uses human embryos for research and to develop cures for diseases.In many countries,the second two types of cloning are illegal.
Dolly the sheep was the product of reproductive cloning.She gave birth to six baby sheep during her life,but by the age of six,she was seriously ill.She had cancer,and was put to sleep.Most sheep live for eleven or twelve years,but Dolly only lived for six years.
While people worry about cloning leading to similarly early deaths in humans,people have many other worries as well.People worry that if we allow cloning,scientists will be able to create copies of people,which many people believe is not natural.People are also concerned about the effect on society,and worry that there will be many clones walking around everywhere.However,cloning does have benefits.DAN cloning can be used to build organs that can be given to people with failing organs who are waiting for transplants.Therapeutic cloning can be used to help disabled people walk again and to help cure diseases such as cancer.Many governments have made therapeutic cloning illegal,though,because it uses embryos for scientific research.Many people do not like the idea of creating new people and animals for science.
Despite the arguments against it,cloning can benefit people all over the world.However,because it means that scientists could copy people,a lot of people would like to see it banned.What these people need to understand is that there are different types of cloning,and that cloning itself is not the problem.The problem is what we choose to use cloning for.
62.Which of the following is reproductive cloning?B
A.Doctors have created a new liver from a single gene.
B.A cat born in a laboratory looks exactly like its mother and has the same DNA.
C.The cure for a deadly disease has been discovered by using a human embryo.
D.A person's cancer is cured.
63.Which type of cloning is illegal in most countries?C
A.DNA cloning and reproductive cloning
B.DNA cloning and therapeutic cloning
C.reproductive cloning and therapeutic cloning
D.reproductive cloning
64.People worry about cloning becauseC.
A.it can be used for transplants
B.it may cause cancer
C.it goes against natural birth
D.they do not like the idea
65.According to the article,the main problem with cloning isC.
A.that people do not know there are three different types
B.that many clones walk around
C.what scientists choose to use it for
D.that the technology is too advanced.
分析 本文主要講述三種克隆,以及人們對于克隆所關(guān)心的問題.
解答 BCCC
62 B 細(xì)節(jié)題. 根據(jù)文章第二 段Reproductive cloning is creating a person or an animal that is genetically exactly the same as another. 可知生殖克隆指的是創(chuàng)造另外一個(gè)基因完全相同的人或者動(dòng)物,故選B.
63 C 細(xì)節(jié)題. 根據(jù)文章第二 段In many countries,the second two types of cloning are illegal.可知后兩種克隆(生殖克隆和治療性克。┰诤芏鄧沂欠欠ǖ,故選C.
64 C 細(xì)節(jié)題. 根據(jù)文章第三 段.People worry that if we allow cloning,scientists will be able to create copies of people,which many people believe is not natural. 可知很多人擔(dān)心克隆的原因是它與自然相違背,故選C.
65 C 細(xì)節(jié)題. 根據(jù)文章最后一段The problem is what we choose to use cloning for.可知克隆最大的問題是我們選擇克隆的用途是什么,故選C.
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