2. 外语
  3. In 1751, Swedish botanist Carolus Linnaeus came up with the novel idea of using flowers as clocks. Morning glories open their tr

In 1751, Swedish botanist Carolus Linnaeus came up with the novel idea of using flowers as clocks. Morning glories open their tr

admin2015-10-21  83
问题     In 1751, Swedish botanist Carolus Linnaeus came up with the novel idea of using flowers as clocks. Morning glories open their trumpet-like petals around 10 a. m. , water lilies at 11 and so on through evening primroses and moonflowers. A full array of these blossoms, planted in a circle, could indicate the time. It was a whimsical notion. But some 250 years later, scientists are seriously interested in the timekeeping mechanisms of nature. "They’re so ubiquitous, they’re almost a signature of life," says molecular neuroscientist Russell Foster of Imperil College, London.
    From cockroaches to humans, Foster explores these internal clocks in a fascinating new book, Rhythm of Life, co-authored with British science writer Leon Kreitzman. The author show how the daily patterns known as circadian rhythms influence far more than our sleep. Heart attacks are more common in the morning. Women tend to go to labor in the evening. Severe asthma prevail at night. Although we may jet across time zones, circadian rhythms rule. The book traces the century-long quest to unravel their mechanisms, with some starting outcomes—including the recent discovery that certain genes switch on and off in 24 hour cycles. Even our responses to medicines may depend on when we take them.
    Nature has devised internal clocks for a simple reason: they aid survival. "The early bird really does get the work,"—thanks to a silent wake-up call before dawn. A mimosa plant spreads its fernlike leaves during the day to create the maximum surface area for photosynthesis, then folds them up at night to reduce water-vapor loss. It’s not a mere response to light. "They do this even when kept in the dark," says biologist Eugene Maurakis of the Science Museum of Virginia.
    In humans, the master clock is a tiny clump of cells in the brain called the suprachiasmatic nuclei. The clocks is reset daily by signals from a novel type of photoreceptor in the eye that Foster discovered. "The blind rely on it, too, provided their eyes haven’t been removed," he says. The result is an orchestrated series of biological events that unfolds in sequence. In the hours before breakfast, the body releases digestive enzymes gradually to be ready for the first meal. Temperature and blood pressure rise in preparation for the day’s demands. This helps explain the morning increase in the heart attacks. Cells reproduce at set times. Hormones rise and fall—many of them according to a predetermined schedule.
    The implications for medicine are profound. By timing treatments to complement daily changes in biochemistry, the authors argues, we can boost efficacy and reduce side effects. In one seminal trial, medical oncologist William Hrushesky of the Dorn V. A. Medical Center in Columbia, S. C. , found that by simply reversing the times when he administered two chemotherapeutic drugs, he could extend survival in women with advanced ovarian cancer from 11 percent at five years to 44 Chronobiology International, more than a dozen ailments can currently benefit from carefully timed treatments. In one recent study, he notes, something as simple as low-dose aspirin at bedtime reduced the rate of preterm deliver in pregnant women at risk for hypertension from 14 percent to zero. Aspirin in the morning had little effect. Surprised? Not to Foster and Kreitzman. As they show, timing is everything.  
Which of the following is INCORRECT concerning the mimosa plant?
选项 A、The mimosa plant unfolds its leaves to get light.
B、The mimosa plant folds leaves to prevent water from losing at night.
C、The mimosa plant devises internal clocks in order to survive.
D、If the mimosa plant is placed in the dark, the internal clocks don’t work very well.
答案D
解析 推断题。根据第三段倒数第一、二句可知，这不仅仅是对光的反应。弗吉尼亚科学博物馆的生物学家Eugene Maurakis说：“它们在黑暗中也如此。”可以判断[D]为错误表述，故为答案。第三段第三句说含羞草在白天时舒展叶子，从而使尽可能大的表面进行光合作用，而晚上为了防止水分蒸发，含羞草的叶子会卷曲。[A]、[B]分别为这两层意思的同义表达，故排除；第三段开头提到，自然界有内部计时功能，原因很简单：内部计时功能帮助它们生存下来。因此[C]也是原文的正确表述，故排除。
转载请注明原文地址:https://kaotiyun.com/show/3TKO777K
0

专业英语八级

相关试题推荐
随机试题
最新回复(0)