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OFFICIAL40 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the 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. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. To review the passage, click VIEW TEXT.Although amphibians are poor thermoregulators, they do have some control over their body temperature.

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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 measured 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 sauvagei 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 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.

14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the 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. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. To review the passage, click VIEW TEXT.Although amphibians are poor thermoregulators, they do have some control over their body temperature.

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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正确答案:BCD
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【题目翻译】说明:下面提供了一个简短总结文章的介绍性句子。通过选择三个答案选项来完成总结,这些选项表达了文章中最重要的观点。有些句子不属于摘要,因为它们表达的观点不是在文章中呈现的,或者是文章中的次要观点。 虽然两栖动物的体温调节器很差,但它们确实可以控制体温。 A:青蛙的生存温度范围从-2°C到41°C不等,这证明两栖动物不受环境温度的影响。 B:两栖动物可以通过暴露在阳光下(日光疗法)和紧贴地面(日光疗法)来提高体温。 C:回避行为,如防晒,以及惊吓和冬眠,帮助两栖动物控制体温。 D:物理适应为两栖动物提供了多种保护方式,以抵御极端或危险的气候条件。 E:日出是两栖动物最需要调节体温的时候。 F:冬眠通常是在泥或沙上挖深洞,而有时只会躲在岩石的裂缝里。 【判定题型】:根据问题的提问方式和6选3的作答方式可以确定该题目为概要小结题。 【选项定位及分析】 根据原文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. 可知蝾螈保持活跃的最低温度是零下2度,青蛙保持活跃的最高温度是零上41度。所以A选项错误。 根据原文The Andean toad Bufo spinulosus exposes itself immediately after sunrise on moist ground and attains its preferred body temperature by this means. 其中exposes itself immediately after sunrise对应B选项中的exposing themselves to the sun. 和原文Thigmothermy is a behavior present in most amphibians, although pressing against the ground serves a dual purpose. 所以B选正确。 根据原文and diurnal and annual avoidance behaviors, which include moving to shelter during the day for cooling and hibernating or estivating, 对应C选项。 根据原文Nocturnal activity in amphibians with low tolerance for high ambient temperatures is a typical thermoregulatory behavior of avoidance.根据原文Physiological adaptations can assist amphibians in colonizing habitats where extreme conditions prevail. 其中extreme conditions对应D选项中的extreme or dangerous climate conditions. 所以E选项错误,体温调节的最佳时间并非是日出之后,而是夜间。 根据原文Summer estivation also occurs by burrowing into the ground or hiding in cool, deep rock crevasses to avoid desiccation and lethal ambient temperature. 所以F选项错误,因为夏眠也是需要挖地洞或者藏在石头裂缝中。

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