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托福写作范文:Cells and Temperature

发布时间:2013-01-13 关键词:托福写作范文:Cells and Temperature

摘要:托福写作范文:Cells and Temperature

 

  有对比才会有发现,又发现才会有进步。托福写作也不例外,多看看别人的文章,有助于改进自己的文章。下面请看,北京新航道托福频道和大家分享的范文:Cells and Temperature

 

  Cells and Temperature

 

  Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C;a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature.来源:北京新航道托福培训

 

  For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into “warm-blooded” and “cold-blooded” species; warm-blooded included mammals and birds whereas all other creatures were considered cold- blooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana-each cold-blooded----usually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called home0therms, and those whose body temperature varies with their environments, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience change in the depths of the ocean never experience change in the chill of the deep water, and their body temperatures remain constant.

 

  上面就是托福写作范文Cells and Temperature 的详细内容,希望大家认真看,从中总结经验技巧,不断地改进和自身的写作水平,争取拿,加油!

 

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