考研考试

【单选题】TheBelgian blue is an ugly but tasty cow that has 40% more muscle than it should have. It is the product of random mutation followed by selective breeding—as, indeed, are all domesticated creatures. But where an old art has led, a new one may follow.By understanding which genetic changes have been consolidated in theBelgian blue, it may be possible to design and build similar versions of other species using genetic engineering as a short-cut.And that is precisely what TerryBradley, a fish biologist at the University of Rhode Island, is trying to do. Instead of cattle, he is doing it in trout. His is one of two projects that may soon put the first biotech animals on the dinner table. The other project is led byAquaBounty.
It is one thing to make such fish, of course. It is quite another to get them to market. First, it is necessary to receive the approval of the regulators. InAmerica, the relevant regulator is the Food andDrugAdministration ( FDA、, whichAquaBounty says it has been petitioning for more than a decade and which published guidelines for approving genetically engineered animals in 2009.AquaBounty has now filed its remaining studies for approval, and hopes to hear the result this year.DrBradley has not yet applied for approval.
The FDA、is concerned mainly with the healthfulness of what people put in their mouths, and it seems unlikely that the new procedures will yield something that is unsafe to eat.But what happens if the creatures escape and start breeding in the wild For that to be a problem, the modified fish would have to be better at surviving and reproducing than those honed by millions of years of natural selection. On the face of it, this seems unlikely, because the characteristics that have been engineered into them are ones designed to make them into better food, rather than lean, mean breeding machines.
But there is a chink in this argument.As MarkAbrahams, a biologist at Memorial University in Newfoundland, points out, it is not just the fish that have been modified by man, but also the environment in which they could escape. Many of the creatures that eat salmon and trout, such as bears and some birds, have had their ranks thinned by human activity.DrAbrahams thinks it possible that fast-growing salmon could displace the natural sort in places where predators are rare.
AquaBounty is addressing such concerns by subjecting developing eggs to high pressures. The result, if all goes well, will be that animals follow plants down the biotech route. Whether people will actually want to buy or eat the new fish is a different matter— though they buy the meat ofBelgian blue cattle at a premium. Perhaps clever marketing could make "double-muscled" fish into a premium product, too. If people will pay extra for meat from a monstrosity like theBelgian blue, anything is possible.
How wasBelgian blue being created
A、It was produced like all other domesticated creatures.
B、It was produced by natural breeding.
C、It was produced using genetic engineering as a short-cut.
D、It was a product of cross breeding.
网考网参考答案：A
网考网解析：
具体细节题 [解析] 文章第一段具体介绍了比利时蓝牛培育的过程，但是由于一些关键词汇比较难，语句较长，因此此题有一定难度。关键在于对这句话的理解：It is the product of random mutation followed by selective breeding—as, indeed, are all domesticated creatures．它是随机突变后加以选择培育的产品。破折号后面的这句话尤为关键，“这正和其他的家畜培育过程一样”。由此可判断[A]选项正确。紧接着，在确定了比利时蓝牛体内是哪种基因产生突变使其肌肉量突增后，可以利用基因工程有针对性地在其他动物体内加入这种基因，这是基因工程带来的一条捷径。[C]选项很具迷惑性，using genetic engineering as a short-cut是根据原文设置的干扰项。但是利用基因工程作为捷径培育出来的并不是比利时蓝牛，而是后文提到的“基因鱼”，比利时蓝牛是基因工程的蓝本。[B]选项natural breeding，自然培育，也不正确，虽然比利时蓝牛不能算作基因工程的产物，但是也是经过人类选择育种培育的，不再是自然培育。[D]选项cross breeding，“杂交”，属错误选项。通过这几个选项，同学们也可以学习几个相关的和基因工程有关的词汇。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>