职称英语考试

试题来源：2015年职称英语《综合类A级》热身模拟试题(2)
    Eat More, Weigh Less, Live Longer
    Clever genetic detective work may have found out the reason why a near starvation dietprolongs the life of many animals.Ronald Kahn at Harvard Medical School in Boston, US, and his colleagues have been ableto extend the lifespan (寿命) of mice by 18 per cent by blocking the rodent's (啮齿动物) increase of fat in specific cells. This suggests that thinness -- and not necessarily diet --promotes long life in "calorie (卡路里) restricted" animals.
    "It's very cool work. " says aging researcher Cynthia Kenyon of the University of California, San Francisco. "These mice eat all they want, lose weight and live longer. It's like heaven."Calorie restrition dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown, partly because few people are willing to submit to such a strict diet.
    But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn's team wondered whether the animals simply benefit by becoming thin.
To find out, they used biology tricks to disrupt the insulin (胰岛素) receptor (受体) gene in lab mice -- but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn.
    This slight genetic change in a single tissue had dramatic effects. By three months of age, Kahn, thoses modified mice had up to 70 per cent less body fat than normal control mice, despite the fact that they ate 55 per cent more food per gram of body weight. In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive.
    "That they get these effects by just manipulating the fat cells is controversial," says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging. But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie-restricted animals. "It might be the same effect or there might be two routes to long life," he points out, "and that would be very interesting. "
Ronald Kahn and his colleagues can make mice live longer by____
A. offering them less food
B. giving them a balanced diet
C. disrupting the specific genes in their fat cells
D. preventing them growing larger

 42

According to the passage, we do not know whether humans will benefit from takingin fewer calories partly because____
A. humans, worms and rodents are different
B. most people are not willing to be put on a strict diet
C. the effect is not known
D. genetic changes in tissues can not be performed on humans

 43

What does the last sentence in the third paragraph imply____?
A. People like to lose weight, but they do not like to eat less.
B. People want to go to heaven, but they do not want to die
C. Mice will go to heaven if they lose weight.
D. Mice enjoy losing weight.

44

The average modified mouse lived____
A. 3 years
B. 753 days
C. More than 3 years
D. 887 days

 
45

What can be inferred from the passage about the route to long life____?
A. It remains to be studied.
B. It has already been discovered.
C. Eating more leads to long life.
D. Eating less leads to long life.

试题出处：http://www.examtiku.com/shiti/6966724721.html
网考网参考答案：C、B、A、D、A
网考网解析：进入考试题库查看解析
大数据分析：根据网考网与考试题库的统计，该试题：
77%的考友选择了A选项
0%的考友选择了B选项
4%的考友选择了C选项
19%的考友选择了D选项
考友解析与评论：
 · 这题答案有争议，我认为选C、B、A、D、A
 · 这个答案有点争议 好像这个考试很多答案都有争议啊
 · 我全答错了