职称英语等级考试试题答案及题解综合类(A级)试题

1、职称英语等级考试试题答案及题解综合类 A 级 试题 6第三篇 Eat More， Weigh Less， Live LongerClever genetic detective work may have found out the reason why a near。 starvation diet prolongs the life of many animals Ronald Kahn at Harvard Medical School in Boston ，US，and his colleagues have been able to extend the lifespan寿命of m

2、ice by 18 per cent by blocking the rodent ' s啮齿动物in crease of fat in specific cells. This suggests that thinn ess-a nd hot necessarily diet -promotes long life in“热Ofe卡® restricted animals“I'ts very cool work. says aging researcher Cynthia Kenyon of the University of California ，San Fra

3、ncisco.“ Thesemice eat all they want， lose weight and livelonger. It' s like heaven. Calorie restriction 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 stri

4、ct 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

5、 benefit by becoming thin.To find out。they used biology tricks to disrupt the insulin 胰岛素receptor受 体ge ne in lab mice _but only in their fat cells . “ Si nee in suli n is n eeded to help fat cells store fat，these animals were protected against becoming fa，t explains KahnThis slight genetic change in

6、 a single tissue had dramatic effectsBy three months of age，Kahn，s modified mice had up to 70 per cent less body fat than normal control mice，despite the fact that they ate 55per cent more food per gram of body weightIn addition ，their lifespan increasedThe average control mouse lived 753 days， whil

7、e the thin rodents averaged a lifespan of 887 daysAfter 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 t11e fat cells is controversial， says Leonard Guarente of the Massachusetts Institute of Techno

8、logy, 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 interestin

9、g 41 Ronald Kahn and his colleagues can make mice live longer byA offering them less foodB giving them a balanced dietC disrupting the specific genes in their fat cells D preventing them growing larger42 According to t11e passage， we d0 not know whether humans will benefit from taking in fewer calor

10、ies partly becauseA humans， worms and rodents are differentB most people are not willing to be put on a strict dietC the effect is not knownD genetic changes in tissues can not be performed on humans43 What does the last sentence in the third paragraph imply?A People like to lose weight ， but they do not like to eat lessB People want to go to heavenbut they do not want to dieC Mice will go to heaven if they lose weight D Mice enjoy losing weight 44 The average modified mouse livedA 3 yearsB 753 daysC More than 3 yearsD 887 days45 What Can be inferred