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托福阅读句子简化题:Biological Clocks

2015-08-18 16:56:51来源:网络

  【托福阅读题型:Biological Clocks句子简化题】托福阅读中句子简化题是重要题型之一。根据托福阅读题型不同来进行专项练习,是短期提高托福阅读能力的有效方法。同学们需要多加练习哦!

  查看全部:托福阅读题型分类练习之句子简化题

  托福阅读句子简化题:Biological Clocks

  【Paragraph 2】When crayfish are kept continuously in the dark, even for four to five months, their compound  eyes continue to adjust on a daily schedule for daytime and nighttime vision. Horseshoe crabs kept in the dark continuously for a year were found to maintain a persistent rhythm of brain activity that similarly adapts their eyes on a daily schedule for bright or for weak light. Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours. Such a rhythm whose period is approximately—but not exactly—a day is called circadian. For different individual horseshoe crabs, the circadian period ranged from 22.2 to 25.5 hours. A particular animal typically maintains its own characteristic cycle duration with  great precision for many days. Indeed, stability of the biological clock's period is one of its major features, even when the organism's environment is subjected to considerable changes in factors, such as temperature, that would be expected to affect biological activity strongly. Further evidence for persistent internal rhythms appears when the usual external cycles are shifted—either experimentally or by rapid east-west travel over great distances. Typically, the animal's daily internally generated cycle of activity continues without change. As a result, its activities are shifted relative to the external cycle of the new environment. The disorienting effects of this mismatch between external time cues and internal schedules may persist, like our jet lag, for several days or weeks until certain cues such as the daylight/darkness cycle reset the organism's clock to synchronize with the daily rhythm of the new environment.(Biological Clocks)

  Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

  ○Stability, a feature of the biological clock's period, depends on changeable factors such as temperature.

  ○A major feature of the biological clock is that its period does not change despite significant changes in the environment.

  ○A factor such as temperature is an important feature in the establishment of the biological clock's period. ○Biological activity is not strongly affected by changes in temperature.

  答案见下一页:

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