托福 新托福 40 - Amphibian Thermoregulation
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In contrast to mammals and birds, amphibians are unable to produce thermal energy through their metabolic activity, which would allow them to regulate their body temperature independent of the surrounding or ambient temperature. However, the idea that amphibians have no control whatsoever over their body temperature has been proven false because their body temperature does not always correspond to the surrounding temperature. While amphibians are poor thermoregulators, they do exercise control over their body temperature to a limited degree.

Physiological adaptations can assist amphibians in colonizing habitats where extreme conditions prevail. The tolerance range in body temperature represents the range of temperatures within which a species can survive. One species of North American newt is still active when temperatures drop to -2°C while one South American frog feels comfortable even when temperatures rise to 41°C—the highest body temperature measured in a free-ranging amphibian. Recently it has been shown that some North American frog and toad species can survive up to five days with a body temperature of -6°C with approximately one-third of their body fluids frozen. The other tissues are protected because they contain the frost-protective agents glycerin or glucose. Additionally, in many species the tolerance boundaries are flexible and can change as a result of acclimatization (long-term exposure to particular conditions).

Frog species that remain exposed to the sun despite high diurnal (daytime) temperatures exhibit some fascinating modifications in the skin structure that function as morphological adaptations. Most amphibian skin is fully water permeable and is therefore not a barrier against evaporation or solar radiation. The African savanna frog Hyperolius viridiflavus stores guanine crystals in its skin, which enable it to better reflect solar radiation, thus providing protection against overheating. The tree frog Phyllomedusa sauvagel responds to evaporative losses with gland secretions that provide a greasy film over its entire body that helps prevent desiccation (dehydration).

However, behavior is by far the most important factor in thermoregulation. The principal elements in behavioral thermoregulation are basking (heliothermy), heat exchange with substrates such as rock or earth (thigmothermy), and diurnal and annual avoidance behaviors, which include moving to shelter during the day for cooling and hibernating or estivating (reducing activity during cold or hot weather, respectively). Heliothermy is especially common among frogs and toads: it allows them to increase their body temperature by more than 10°C. The Andean toad Bufo spinulosus exposes itself immediately after sunrise on moist ground and attains its preferred body temperature by this means, long before either ground or air is correspondingly warmed. A positive side effect of this approach is that it accelerates the digestion of the prey consumed overnight, thus also accelerating growth. Thigmothermy is a behavior present in most amphibians, although pressing against the ground serves a dual purpose: heat absorption by conductivity and water absorption through the skin. The effect of thigmothermy is especially evident in the Andean toad during rainfall: its body temperature corresponds to the temperature of the warm earth and not to the much cooler air temperature.

Avoidance behavior occurs whenever physiological and morphological adaptations are insufficient to maintain body temperature within the vital range. Nocturnal activity in amphibians with low tolerance for high ambient temperatures is a typical thermoregulatory behavior of avoidance. Seasonal avoidance behavior is extremely important in many amphibians. Species whose habitat lies in the temperate latitudes are confronted by lethal low temperatures in winter, while species dwelling in semiarid and regions are exposed to long dry, hot periods in summer.

In amphibians hibernation occurs in mud or deep holes away from frost. North of the Pyrenees Mountains, the natterjack toad offers a good example of hibernation, passing the winter dug deep into sandy ground. Conversely, natterjacks in southern Spain remain active during the mild winters common to the region and are instead forced into inactivity during the dry, hot summer season. Summer estivation also occurs by burrowing into the ground or hiding in cool, deep rock crevasses to avoid desiccation and lethal ambient temperature. Amphibians are therefore hardly at mercy of ambient temperature, since by means of the mechanisms described above they are more than) exercise some control over their body temperature.

题目
10.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selected THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

A number of factors may help account for the difference in biodiversity between low and high latitudes.
A.Frogs, which survive temperature ranges from as low as -2°C to as high as 41°C, are evidence that amphibians are independent of ambient temperatures
B.Amphibians can increase their body temperature by exposing themselves to the sun (heliothermy) and by pressing against the ground (thigmothermy).
C.Avoidance behaviors, such as sheltering from the sun, as well as estivation and hibernation,help amphibians control their body temperature.
D.Physical adaptations offer amphibians a number of ways to protect against extreme or dangerous climate conditions.
E.Sunrise is the time when some amphibian species have the greatest need for thermoregulatory mechanisms.
F.Hibernation always involves digging deep holes in mud or sand, whereas estivation sometimes involves nothing more than hiding in deep rock crevasses.
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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?
  • 以沫
    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
  • wx_6697
    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
  • wx_6697
    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
  • wx_8861
    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?
  • wx_6697
    求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
  • 与托福的斗争史
    与托福的斗争史 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
    B哪里错了
  • 小雨淅沥哗啦的下
    小雨淅沥哗啦的下 去解答
    B为啥不对
  • 李浩然
    B选项错误,是因为残缺么?
  • wx_100
    请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
  • wx xxxxx
    请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
  • wx_7695
    鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
  • haiyuqiao
    @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
  • wx_2065
    鑫哥,想知道E错在哪里?
  • wx_7695
    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
    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
    interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
  • 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.
  • 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?
  • 以沫
    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
  • wx_6697
    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
  • wx_6697
    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
  • wx_8861
    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?
  • wx_6697
    求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
  • 与托福的斗争史
    与托福的斗争史 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
    B哪里错了
  • 小雨淅沥哗啦的下
    小雨淅沥哗啦的下 去解答
    B为啥不对
  • 李浩然
    B选项错误,是因为残缺么?
  • wx_100
    请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
  • wx xxxxx
    请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
  • wx_7695
    鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
  • haiyuqiao
    @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
  • wx_2065
    鑫哥,想知道E错在哪里?
  • wx_7695
    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
    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
    interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
  • 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.