托福 新托福 15 - A Warm Blooded Turtle
题目
1 2 3 4 5 6 7 8 9 10
6.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.
  • A.In a turtle's countercurrent exchange system, outgoing vessels lie near enough to ingoing ones that heat can be exchanged from the former to the latter before reaching the turtle's flippers.
  • B.Within the turtle's flippers, there is a countercurrent exchange system that allows colder blood vessels to absorb heat from nearby warmer blood vessels and then return warmed blood to the turtle's body.
  • C.In a countercurrent exchange system, a turtle can pick up body heat from being close enough to other turtles, thus raising its blood temperature as it passes them.
  • D.When a turtle places its flippers close to its body, it is able to use its countercurrent exchange system to transfer heat from the warmer blood vessels in its body to the cooler blood vessels in its flippers.
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    阅读原文 中文译文

    When it comes to physiology, the leatherback turtle is, in some ways, more like a reptilian whale than a turtle. It swims farther into the cold of the northern and southern oceans than any other sea turtle, and it deals with the chilly waters in a way unique among reptiles.

    A warm-blooded turtle may seem to be a contradiction in terms. Nonetheless, an adult leatherback can maintain a body temperature of between 25 and 26°C (77-79°F) in seawater that is only 8°C (46.4°F). Accomplishing this feat requires adaptations both to generate heat in the turtle’s body and to keep it from escaping into the surrounding waters. Leatherbacks apparently do not generate internal heat the way we do, or the way birds do, as a by-product of cellular metabolism. A leatherback may be able to pick up some body heat by basking at the surface; its dark, almost black body color may help it to absorb solar radiation. However, most of its internal heat comes from the action of its muscles.

    Leatherbacks keep their body heat in three different ways. The first, and simplest, is size. The bigger the animal is, the lower its surface-to-volume ratio; for every ounce of body mass, there is proportionately less surface through which heat can escape. An adult leatherback is twice the size of the biggest cheloniid sea turtles and will therefore take longer to cool off. Maintaining a high body temperature through sheer bulk is called gigantothermy. It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. It apparently works, in a smaller way, for some other sea turtles. Large loggerhead and green turtles can maintain their body temperature at a degree or two above that of the surrounding water, and gigantothermy is probably the way they do it. Muscular activity helps, too, and an actively swimming green turtle may be 7°C (12.6°F) warmer than the waters it swims through.

    Gigantothermy, though, would not be enough to keep a leatherback warm in cold northern waters. It is not enough for whales, which supplement it with a thick layer of insulating blubber (fat). Leatherbacks do not have blubber, but they do have a reptilian equivalent: thick, oil-saturated skin, with a layer of fibrous, fatty tissue just beneath it. Insulation protects the leatherback everywhere but on its head and flippers. Because the flippers are comparatively thin and blade-like, they are the one part of the leatherback that is likely to become chilled. There is not much that the turtle can do about this without compromising the aerodynamic shape of the flipper. The problem is that as blood flows through the turtle’s flippers, it risks losing enough heat to lower the animal’s central body temperature when it returns. The solution is to allow the flippers to cool down without drawing heat away from the rest of the turtle’s body. The leatherback accomplishes this by arranging the blood vessels in the base of its flipper into a countercurrent exchange system.

    In a countercurrent exchange system, the blood vessels carrying cooled blood from the flippers run close enough to the blood vessels carrying warm blood from the body to pick up some heat from the warmer blood vessels; thus, the heat is transferred from the outgoing to the ingoing vessels before it reaches the flipper itself. This is the same arrangement found in an old-fashioned steam radiator, in which the coiled pipes pass heat back and forth as water courses through them. The leatherback is certainly not the only animal with such an arrangement; gulls have a countercurrent exchange in their legs. That is why a gull can stand on an ice floe without freezing.

    All this applies, of course, only to an adult leatherback. Hatchlings are simply too small to conserve body heat, even with insulation and countercurrent exchange systems. We do not know how old, or how large, a leatherback has to be before it can switch from a cold-blooded to a warm-blooded mode of life. Leatherbacks reach their immense size in a much shorter time than it takes other sea turtles to grow. Perhaps their rush to adulthood is driven by a simple need to keep warm.


    从生理学上讲,棱皮龟在某些方面上更像爬行的鲸鱼。跟其他海龟相比,它们能够游入更寒冷的北部和南部海洋,并且和其他爬行类动物相比,它们在应对寒冷水域时有其独特的方式。 温血海龟似乎是一个自相矛盾的术语。尽管如此,成年棱皮龟能够在仅8摄氏度(46.4华氏度)的海水中将体温维持在25~26摄氏度(77-79华氏度)之间。棱皮龟要做到这一点就必须调节其自身的体温,还要防止温度散失到周围水域。很显然,棱皮龟产生体内热量的方式与我们或者鸟类不同,并非细胞代谢的副产物。棱皮龟可能会通过晒太阳来收集身体所需的热量。其深色近乎黑色的体色有助于吸收太阳辐射。然而,它的大部分体热来自于肌肉运动。 棱皮龟通过三种方式保持体温。第一种也是最简单的方式就是体型大小。动物体型越大,表面和体积的比例越小。体重每增加一盎司,相应的容易流失热量的表面就越少。成年棱皮龟是最大的海龟的两倍,因此它变凉就需要更久的时间。完全依靠庞大体积维持体温的方法叫巨温性。大象、鲸鱼也许包括很多恐龙也是通过这种方法保持体温的。其它海龟或多或少也存在这种现象。红海龟和绿甲海龟可以维持与周围水温略高1摄氏度或2摄氏度或的体温,可能就是利用的巨温性。肌肉运动也有助于维持体温,一个活跃游水的绿海龟体温可能比它所游水域温度高7摄氏度(12.6华氏度)。 然而,在寒冷的北部水域巨温性不足让棱皮龟保暖。同样,对于通过厚厚的绝缘脂(脂肪)来维持体温的鲸鱼来说也是不够的。棱皮龟没有鲸鱼那样的脂肪,但是它们和爬行类的动物有着相似的结构:厚且含油的皮肤,皮肤下有一层纤维,而脂肪组织就在这个纤维层下面。除了头部和鳍,这个“绝缘”结构可以保护它们的所有部位。因为棱皮龟的鳍相对较薄且呈叶片状,这一部位很有可能会被冻僵。在不损害鳍部气动外形的情况下很少有海龟可以做到这些。问题是血液流经海龟鳍部时,很容易损耗热量,血液回流时便降低了动物的中心体温。解决办法是在身体其余部分的热量还没有损耗前,允许鳍部降低温度。棱皮龟通过鳍下排列的血管流入逆流交换系统来实现这一点。 在逆流交换系统中,血管将鳍部冷却的血液与身体其他部位温热的血液进行交换。因此,热量在到达鳍部前就通过流入的血液和流出的血液完成了热量转移。人们发现老式蒸汽式暖气片有着与之类似的装置,当水流经这些盘绕的管子时热量进行了交换。当然并不只是棱皮龟有这种结构。海鸥的腿部也有一个逆流交换系统,这就是为什么海鸥可以站在冰川上而不被冻结。 当然,这些都仅适用于成年棱皮龟。刚孵化的棱皮龟太小,即使有绝缘层和逆流交换系统也不能保存体温。现在我们还不知道棱皮龟要达到多大年龄或者多大尺寸才能从冷血动物转变成温血动物。棱皮龟庞大体型的形成时间要比其它海龟短得多。可能它们是为了保暖才急着向成年过渡。

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    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
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      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
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      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
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      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
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      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
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      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
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    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
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      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
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      鑫哥,想知道E错在哪里?
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      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
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    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.