题目内容
Livestock(牲畜） cloning is the practice of cloning sheep,cattle and other livestock species as a way to improve efficiency. The basic idea behind livestock cloning is to clone animals that have certain qualities,such as cows that produce more milk or meat. 1 However,this practice is very controversial,and livestock farmers have been hesitant to adopt it fully because of public opposition and certain inefficiencies.
In technical terms,livestock are cloned by taking cells from one animal and using them to fertilize eggs(使卵子受精) .Scientists take the fertilized eggs and put them in female animals. 2 Many animals are bom with abnormal shapes. Scientists are looking for ways to improve the process and make it less expensive to adopt on a wider scale.
3 For example,if farmers were able to take only their very best animals and recreate them many times,they could potentially be more productive.
There are also some potential problems with cloned livestock. 4. For example,when a disease hits,there are usually individuals who cannot be harmed by the disease or are more resistant,and they will generally survive. If all the animals were genetically (在基因方面) identical or similar,this sort of disease could totally destroy an entire generation of livestock,leaving the world with a massive food shortage.
In addition to concerns about genetic diversity,there are other concerns about cloning. 5 There are also some people who worry that livestock cloning research may be a gateway to introducing human cloning,which is widely disapproved of.
A. Are the surviving clones really clones?
B. Therefore,the new species is expected to be better.
C. The biggest one arises from a reduction in genetic diversity.
D. Cloned livestock have the potential to provide some major benefits.
E. Cloning animals shows us what might happen if we try to clone humans.
F. These concerns sometimes come from worries over unforeseen consequences.
G. This process doesn't always work perfectly,and it can be relatively expensive.
(科普知识与现代技术)
本文是说明文。文章介绍了牲畜克隆技术。
1. B. 根据上一句内容可知，如果能克 隆出生产更多奶和肉的牛，那么“这 个新品种应该是更好”。
2. G。根据本空后的Many animals are bom with abnormal shapes ... make it less expensive可知，自前克隆的 “过程不能总是完美，而且价格相对 比较昂贵”。
3. D. 根据本空后的内容不难看出， 这里是介绍克隆牲畜的“好处”。
4. C. 根据本空后内容可知，克隆技术 会减少“基因多样性”，所以当拥有 同样基因的动物遭受某种致命疾病 时，所有的这些动物都会死亡。
5. F。本空前的concerns提示了本题 答案。
