[外语类试卷]国家公共英语五级(阅读理解)练习试卷8及答案与解析.doc
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1、国家公共英语五级(阅读理解)练习试卷 8及答案与解析 Part A Directions: Read the following texts and answer the questions which accompany them by choosing A, B, C or D. Mark your answers on ANSWER SHEET 1. 0 Tobaccos public image couldnt be more stained these days, given the war on cigarettes in the courts, federal and state
2、 governments, the medical establishment even in Doonesbury. But the tobacco plant is not an irredeemable never-do-well. Because its genetic makeup is fairly straightforward and well understood, scientists believe tobacco could turn out to be the perfect blotch factory for protein-based drags. By spl
3、icing human genes a technique developed in the early 1990s researchers have enabled tobacco plants to produce a number of drugs and vaccines and even human blood components. Within 10 years, researchers are hopeful that tobacco farmers might be raising millions of acres of biofactories rather than “
4、the killer weed“. The latest breakthrough in tobacco “pharming“ may bring such a vision one step closer to reality. Scientists at Monsanto Co. (MTC) reported in the March issue of Nature Biotechnology that they were able to genetically engineer tobacco plants to produce human growth hormone, otherwi
5、se known as somatotropin an extremely costly drug used to treat dwarfism. But the Monsanto discovery was more important for the press than the product. The scientists were able to induce the tobacco plants to manufacture the drug in an abundant piece of the plant cell known as a chloroplast, which i
6、s responsible for converting light into food. Other efforts to create drug-producing plants have altered plant nuclei instead far less numerous cell components. DNA Dilemma. “We were able to produce 300-fold more human somatotropin in the chloroplasts than in the nucleus,“ says Jeffrey M. Staub, man
7、ager of the Monsanto team that developed the technique. “As an optimistic scientist, I think it is very reasonable to believe, we will be able to produce commercial quantities of human proteins in the plants in the next couple of years.“ There has been notable progress with gene-spliced plants in th
8、e past two years. In 1998, British researchers reported that a human antibody grown in tobacco plants prevented one of the bacterial infections that led to tooth decay in human volunteers. And last August, the Energy Dept.s Pacific Northwest National Laboratory announced that its scientists had succ
9、essfully transplanted the necessary human genes into tobacco plants to produce human blood components. Even with plants, though, volume remain a problem. All plant cells contain subunits called organelles, two of which are the nucleus and the chloroplast. Gene splicing to date has focused on alterin
10、g the nucleus essentially the brain of the cell, because it controls all of the plants activities. But drug production was limited, since there is only one nucleus per cell. Moreover, the genetic alteration is transmitted to the plants pollen, making it difficult to control the spread of the reengin
11、eered plants. Chloroplasts, however, are abundant, and they do not spread their genetic changes to any other cells in the plant. 1 What does the passage mainly discuss? ( A) Tobaccos public image will never change. ( B) Chloroplast will make tobacco change its social role. ( C) Nuclei is more import
12、ant than chloroplast. ( D) DNA Dilemma is very optimistic. 2 The word “breakthrough“ in the 1st sentence of the 2nd paragraph is closest in meaning to _. ( A) breakaway ( B) breakdown ( C) a sudden important development ( D) the illegal entering of a building 3 Which of the following statements is N
13、OT true? ( A) Somatotropin is used to treat dwarfism. ( B) Nuclei is far less numerous component. ( C) Chloroplast is responsible for converting light into food. ( D) Somatotropin is not of hormone. 4 Based on the information of the last paragraph, which of the following is true? ( A) The number of
14、chloroplasts is limited. ( B) Chloroplasts do not spread their genetic changes to other cells in the plant. ( C) Nucleus and chloroplast are all the subunits that plant cells contain. ( D) Gene splicing date has focused on altering all the organelles. 5 It can be inferred from the text that _. ( A)
15、tobacco may finally have a chance to transcend its societal role as a cancer-causing blight ( B) tobacco should be prohibited to plant ( C) cigarettes will be accepted by scientists ( D) tobacco plants cannot be used to produce hormone Part B Directions: In the following article some paragraphs have
16、 been removed. For Questions 66-70, choose the most suitable paragraph from the list A-F to fit into each of the numbered gaps. There is one paragraph which does not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. 5 Opinion polls repeatedly tell us that the only thing Americans worry ab
17、out more than the environment is their health. This is entirely understandable, for health is obviously preferable to illness. What makes todays preoccupation with health slightly surprising is that Americans are far healthier now than they have ever been. 16._ Nonetheless, health and the various th
18、reats to it remains everyones permanent concern. After all, more than half of us will die from either heart disease or cancer, if current trends continue. 17._ For instance, AIDS if you get it will probably be fatal after a number of years. Cancer induced by smoking or exposure to radiation, on the
19、other hand, may take 20 to 30 years before its catastrophic effects show up. In making choices about health risks, therefore, it is important to bear in mind the likely time lag between taking a risk and suffering its consequences. Those with a mind to “live for today“ are apt to be indifferent to h
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