题目

A.      Out-of-Body Factors on Biological Clocks B.      Brain Cells Controlling Biological Clocks C.      Biological Clocks Controlling Birds Flying D.     Benefits Studying Biological Clocks E.      Inside-Body Factors on Biological Clocks F.      Biological Clocks Controlling Activities 76. Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells plants when to form flowers and when the flowers should open. It tells insects when to leave the protective cocoon and fly away, and it tells animals and human beings when to eat, sleep and wake. 77.     Events outside the plant and animal affect the actions of some biological clock. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the number of hours of daylight. In the short days of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer. 78.     Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration flight twice each year. Birds prevented from flying become restless when it is time for the trip. But they become calm again when the time of flight has ended. 79.     Scientist say they are beginning to learn which parts of the brain contain biological clock. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain seems to control the timing of some of our actions. These cells tell a person when to awake, when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities. 80.     Dr. Moorhead is studying how our biological clocks affect the way we do our work. For example, most of us have great difficulty if we often change to different work hours. It can take many days for a human body to accept the major change in work hours. Dr. Moorhead said industrials officials should have a better understanding of biological clocks and how they affect workers. He said such understanding could cut sickness and accidents at work and would help increase a factory’s production. 答案：FAEBD

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