[外语类试卷]专业英语八级(科学技术类阅读理解)模拟试卷1及答案与解析.doc
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1、专业英语八级(科学技术类阅读理解)模拟试卷 1及答案与解析 0 It is not often that biologists have a chance to watch natural selection in action. The best-known casesthe evolution of resistance to antibiotics in bacteria and to pesticides in insectsare responses to deliberate changes people have made in the environment of the cr
2、eatures concerned. But mankind has caused lots of accidental changes as well, and these also offer opportunities to study evolution. Recently, two groups of researchers, one at New York University (NYU) and the other at the Woods Hole Oceanographic Institute in Massachusetts, have taken advantage of
3、 one of these changes to look at how fish evolve in response to environmental stress. The stress in question is pollution by polychlorinated biphenyls (PCBs). These chemicalswidely used in the middle decades of the 20th century to manufacture electrical insulation, coolants, sealants and plasticiser
4、soften ended up dumped in lakes, rivers and coastal waters. Eventually, such dumping was banned (in America, this happened in 1977). But PCBs are persistent chemicals, and their effects are felt even today. In particular, they disrupt the immune systems of animals such as fish, cause hormonal imbala
5、nces and promote tumours. As is the way of evolution, however, some fish species have developed resistance to PCB poisoning. Isaac Wirgin, at NYU, and Mark Hahn, at Woods Hole, have been studying PCB-re-sistant fish, to see how they do it. After that, the two researchers will be able to look at how
6、these populations evolve yet again as the environment is cleaned up. The species of interest to Dr Wirgin is the Atlantic tomcod of the Hudson river in upstate New York. Part of the Hudson was polluted with PCBs by two General Electric plants. Dr Hahn is looking at a different animal, the killifish,
7、 in New Bedford harbour, Massachusetts, which was polluted by other producers. Both Hudson tomcod and New Bedford killifish are able to tolerate levels of PCB far higher than those that would kill such fish in cleaner waters. The question is, why? PCBs do their damage by binding to a protein called
8、the aryl hydrocarbon receptor, or AHR, thus stopping it working properly. AHR is a transcription factor, meaning that it controls the process by which messenger molecules are copied from genes. These messenger molecules go on to act as the blueprints for protein production, so preventing a transcrip
9、tion factor from working can cause all sorts of problems. Both Hudson tomcod and New Bedford killifish, however, have unusual AHR molecules. And it is this that seems to explain their immunity. A protein is a chain of chemical units called amino acids. In tomcods, AHR is composed of 1,104 such units
10、. Except that in Hudson tomcod it frequently isnt. These fish generally have 1,102 amino acids in their AHRs. The two missing links in the chain (a phenylalanine and a leucine, for aficionados) are encoded in the gene for ordinary tomcod AHR by six genetic “letters“ that are missing from the DNA fou
11、nd in PCB-resistant Hudson tomcod. The shortened version of AHR does not bind nearly so easily to PCBs. It still, however, seems to work as a transcription factor. The result is fish that are more or less immune to PCB poisoning. In the case of the New Bedford killifish the situation is similar, but
12、 more complicated. There are no missing amino acids. Dr Hahn has, however, found nine places along the amino-acid chain of killifish AHR where the link in the chain varies between individuals. Altogether, he has identified 26 such variations. Two of them seem particularly resistant to the effects of
13、 PCBs. It is not that the pollutants do not bind to the proteinthey do. But the protein does not seem to mind. It appears to work equally well, whether or not it has PCB passengers on board. These fishy cases are reminiscent of the peppered moth in Britain. This, too, evolved in response to industri
14、al pollution. It developed black wings, so that it was invisible when it settled on soot-covered tree trunks. Now, with the clean air brought by anti-pollution legislation, British peppered moths are once again peppered. Both the Hudson river and New Bedford harbour are being cleaned up, too. This y
15、ear, for example, General Electric will dredge 1.8m cubic metres (2.4m cubic yards) of PCB-contaminated sediment out of 60km (35 miles) of the Hudson. Dredging will continue over the next few years, after which the river should be PCB-free. It is possible that the tomcod and the killifish will then
16、evolve again, just as the peppered moth did, if their PCB-resistant proteins are not absolutely as good as the original versionswhich they might not be, given that evolution did not find them before. If that happens, Dr Wirgin and Dr Hahn will be watching. From The Economist, October 29, 2011 1 What
17、s the main idea of the passage? ( A) Human-being has made both deliberate and accidental changes to environment. ( B) How fish evolve in response to environmental stress. ( C) The effects of PCBs pollution on the sea environment. ( D) How the PCB-resistant fish evolve in natural courses. 2 Which of
18、the following statements is TRUE? ( A) The killifish are able to resist any other pollutant than PCBs. ( B) The tomcods genes are somewhat abnormal. ( C) The Hudson tomcod misses six genetic letters. ( D) The fish would probably evolve again if the water is cleaned up. 3 According to paragraph 5, wh
19、ich of the following words best describes the function of a “transcription factor“? ( A) preventer ( B) regulator ( C) mediator ( D) repellant 4 Whats the authors intention by bringing the “peppered moth“ up? ( A) To bring back the old memories of environmental protection. ( B) To serve as a contras
20、t to the Hudson river tomcod and New Bedford killifish. ( C) To provide a prospect for the future evolution of the tomcod and the killifish. ( D) To give a very good example of similar cases. 4 Five years ago, Research in Motion, maker of the BlackBerry, was one of the most acclaimed technology comp
21、anies in the world. The BlackBerry dominated the smartphone market, was a staple of the business world, and had helped make texting a mainstream practice. Terrifically profitable, the phone became a cultural touchstonein 2006, a Websters dictionary made “CrackBerry“ its word of the year. These days,
22、 it seems more like the SlackBerry. Thanks to the iPhone and Android devices, R.I.M.s smartphone market share has plummeted; in the U.S., according to one estimate, it fell from forty-four percent in 2009 to just ten percent last year. The BlackBerrys reputed addictive-ness now looks like a myth; a
23、recent study found that only a third of users planned to stick with it the next time they upgraded. R.I.M.s stock price is down seventy-five percent in the past year, and two weeks ago the company was forced to bring in a new C.E.O. The Times wondered recently whether the BlackBerry will go the way
24、of technological dodoes like the pager. The easy explanation for what happened to R.I.M. is that, like so many other companies, it got run over by Apple. But the real problem is that the technology world changed, and R.I.M. didnt. The BlackBerry was designed for businesses. Its true customers werent
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