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共用题干 第一篇A meager（不足的）diet may give you health and long life, but it's not m...

admin2020-12-24  18
问题 共用题干
第一篇

A meager（不足的）diet may give you health and long life, but it's not much fun一and it might not even be necessary. We may be able to hang on to most of that youthful（有青春活力的）vigor （精力）even if we don't start to diet until old age.
Stephen Spindler and his colleagues from the University of California at Riverside have found that some of an elderly mouse's liver genes can be made to behave as they did when the mouse was young simply by limiting its food for four weeks. The genetic rejuvenation（恢复活力，返老还童） won't reverse other damage caused by time for the mouse,but could help its liver metabolize（使进入新陈代谢过程）drugs or get rid of toxins.
Spindler's team fed three mice a normal diet for their whole lives,and fed another three on half-rations.Three more mice were switched from the normal diet to half-feed for a month when they were 34 months old一equivalent to about 70 human years.
The researchers checked the activity of 11,000 genes from the mouse livers,and found that 46 changed with age in the normally fed mice.The changes were associated with things like inflammation and free radical production一probably bad news for mouse health.In the mice that had dieted all their lives,27 of those 46 genes continued to behave like young genes.But the most surprising finding was that the mice that only started dieting in old age also benefited from 70 percent of these gene changes.
"This is the first indication that these effects kick in pretty quickly",says Huber Warner from the National Institute on Aging near Washington D.C.
No one yet knows if calorie restriction works in people as it does in mice,but Spindler is hopeful."There's attracting and tempting evidence out there that it will work,"he says.
If it does work in people,there might be good reasons for rejuvenating the liver. As we get older,our bodies are less efficient at metabolizing drugs,for example.A brief period of time of dieting,says Spindler,could be enough to make sure a. drug is effective.
But Spindler isn't sure the trade-off is worth it."The mice get less disease,they live longer,but they're hungry,"he says."Even seeing what a diet does,it's still hard to go to a restaurant and say:I can only eat half of that."
Spindler hopes we soon won't need to diet at all. His company,Lifespan Genetics in California, is looking for drugs that have the effects of calorie restriction.
选项 What can be inferred about completely normally fed mice mentioned in the passage?
A:They will not experience free radical production.
B:They will experience more genetic rejuvenation in their lifetime.
C:They have more old liver genes to behave like young genes.
D:They are more likely to suffer from inflammation.
答案D
解析第一段第一句讲“节食可能不是非做不可的事”，第二句讲“即使在年老以后才开始节食，我们也能保持大部分的青春活力”，因此，“我们必须从小就开始节食”是错误的，D是答案。
第二段提及“一只高龄老鼠”的时候，作者谈到，“只要连续四周限制一些衰老的老鼠进食，它们的肝脏基因就会变得和衰老前一样充满活力”。据此，“为了阐明节食对老鼠所产生的影响”最好地回答了题干中的问题。
第四段提到，“正常饲养的老鼠随着年龄的增长有46个肝脏基因会发生变化。这种变化与诸如炎症和体内自由基的产生有关”。因此D正确。
第四段最后一句讲“但最惊人的发现是那些上了年纪才开始节食的老鼠也能从70％的基因变化中受益”。“最惊人的”自然是“最令研究人员感兴趣的”。
文章的最后两段谈及Spindler对节食的看法。首先，他不能肯定节食是否值得；其次，他希望在不久的将来，我们不必节食。所以我们可以推知，他认为节食不是得以健康长寿的好办法。
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