题型:阅读理解 题类:常考题 难易度:困难
2017届江苏南通中学高三上期中考试英语卷
Scientists are debating how to limit their newly-discovered power to change genetic structure (结构). Scientists already modify the genes (基因) of farm animals and agricultural plants to make them more productive or stronger. But now they can also change genes in wild animals and plants. These genes would continue into later generations. For example, it may be possible for scientists to remove from existence the kind of mosquitoes, small flying insects, that carry the Zika virus. They might also be able to permanently remove species (物种) of plants and animals that are damaging to other species.
In a report published last week, the U. S. National Academies of Sciences, Engineering and Medicine (NAS) said it supports continued research on this kind of gene control. But it warned that it is not possible to know what will happen when these changed plants and animals are released (释放) into the wild.
Sixteen biologists, ethicists (伦理学家) and policymakers are on an NAS committee that is examining the issue. They say that there is value to the new technology. But, they say, there is not enough evidence to support the release of modified organisms (生物体) from the laboratory into nature.
Many people would support stopping mosquitoes and rats from carrying diseases. But scientists say we must understand the possible scientific, ethical, legal and social results of such action before we decide whether to take it. Gene modification is spread through reproduction (繁殖).
Changed genes will continue to spread as long as an animal or plant continues to reproduce. They cannot be limited to a farm or kept within a country's borders. Scientists are wondering what may happen if a modified organism mates with another species. They are not yet sure how the modified genes would affect the other species. It is possible that those genes could harm those creatures or even lead to their disappearance from our planet.
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