TPO15托福阅读Passage1 A Warm-Blooded Turtle文本+题目原文+答案解析

A Warm-Blooded Turtle

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 sea water 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 gigantotherrny. ■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.

TPO15托福阅读Passage1 A Warm-Blooded Turtle 题目

Question 1 of 13: The phrase“unique among”  in the passage is closest in meaning to

A. natural to

B. different from all other

C. quite common among

D. familiar to

Question 2 of 13: What can be inferred about whales from paragraph 1?

A. They are considered by some to be reptiles.

B. Their bodies are built in a way that helps them manage extremely cold temperatures

C. They are distantly related to leatherback turtles.

D. They can swim farther than leatherback turtles.

Question 3 of 13: The word “feat” in the passage is closest in meaning to

A. remarkable achievement

B. common transformation

C. daily activity

D. complex solution

Question 4 of 13: Paragraph 2 mentions all of the following as true about the body heat of adult leatherback turtles EXCEPT:

A. Their muscles produce heat for maintaining body temperature.

B. Their dark bodies help trap solar radiation.

C. Their cellular metabolism produces heat as a by-product.

D. Basking at the water’s surface helps them obtain heat.

Question 5 of 13: The word“ bulk”in the passage is closest in meaning to

A. strength

B. effort

C. activity

D. mass

Question 6 of 13: The word“it”  in paragraph 4 refers to

A. the problem

B. blood

C. the turtle

D. body temperature

Question 7 of 13: According to paragraph 4, which of the following features enables the leatherback turtle to stay warm?

A. An insulating layer of blubber

B. A thick, oily skin covering fatty tissue

C. The aerodynamic shape of its flippers

D. A well-insulated head

Question 8 of 13:  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.

Question 9 of 13: Why does the author mention old-fashioned steam radiator in the discussion of countercurrent exchange systems?

A. To argue that a turtle' s central heating system is not as highly evolved as that of other warm blooded animals

B. To provide a useful comparison with which to illustrate how a countercurrent exchange system works

C. To suggest that steam radiators were modeled after the sophisticated heating system of turtles

D. To establish the importance of the movement of water in countercurrent exchange systems

Question 10 of 13: The phrase courses through in the passage is closest in meaning to

A. rises through

B. heats up in

C. runs through

D. collects in

Question 11 of 13: According to paragraph 6, which of the following statements is most accurate about young leatherback turtles?

A. They lack the countercurrent exchange systems that develop in adulthood.

B. Their rate of growth is slower than that of other sea turtles.

C. They lose heat easily even with insulation and countercurrent exchange systems.

D. They switch between cold-blooded and warm-blooded modes throughout their hatchling stage.

Question 12 of 13: Look at the four squares [█] that indicate where the following sentence could be added to the passage.

However, these animals have additional means of staying warm.

Where would the sentence best fit?

A. It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. 

B. It apparently works, in a smaller way, for some other sea turtles. 

C. 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.

D. Muscular activity helps, too, and an actively swimming green turtle may be 7°C (12.6° F) warmer than the waters it swims through.

Question 13 of 13: 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.

Contrary to what we would expect of reptiles, the leatherback turtle is actually warm-blooded.

Answer Choices

A. Even though they swim into cold ocean waters, leatherbacks maintain their body heat in much the same way as sea turtles in warm southern oceans do.

B. The leatherback turtle uses a countercurrent exchange system in order to keep the flippers from drawing heat away from the rest of the body.

C. The shape of the leatherback turtle's flippers is especially important in maintaining heat in extremely cold northern waters.

D. The leatherback turtle is able to maintain body heat through sheer size.

E. Leatherbacks have an insulating layer that can be considered the reptilian version of blubber.

F. Young leatherbacks often do not survive to adulthood because they are not able to switch from a cold-blooded way of life to a warm-blooded one quickly enough.

TPO15托福阅读Passage1A Warm-Blooded Turtle 真题解析

Question 1 of 13

正确答案：B

解析：unique独特，那么unique among就是“在……之间很独特”的意思，所以答案是B。

Question 2 of 13

正确答案：B

解析：以whale做关键词定位至第一句，说leatherback turtle更像是爬行的鲸而不像龟类。说明这种龟和鲸有相似之处。后面就说到：这种龟能游到更寒冷的北部和南部海洋。由此可以推出鲸类御寒能力也很强。选B。A是迷惑选项，原文中只是做了一个比喻，本意是说这种龟就像鲸一样，只不过龟还是爬行动物，但实际上鲸本身不是爬行动物。C和D原文中都没提到。

Question 3 of 13

正确答案：A

解析：feat的意思是成就，选A。另外，通过前一句意思也能推测出feat的意义。前文说到leatherback 龟可以在仅有8°C的海水中维持25-26°C的体温。这显然是一个了不起的成就。

Question 4 of 13

正确答案：C

解析：EXCEPT题，排除法。A的muscles做关键词定位至第二段最后一句，提到可以通过肌肉活动获得热量，正确，不选；B的dark body做关键词定位至倒数第二句，提到黑色体表可以捕获太阳辐射，正确，不选；C的by-product做关键词定位至第四句，但原文说leatherbacks不像我们和鸟类那样新陈代谢产生热量，所以与C说的刚好相反，C是答案；D的basking和surface做关键词定位至倒数第二句，说这种龟会在海水表面晒太阳获得热量，正确，不选。

Question 5 of 13

正确答案：D

解析：bulk“大体积”，所以答案是D，mass，大块头。前面提到leatherbacks用三种方法保持体温，首先最简单的就是体积，体积大，散热慢。然后说到这种利用____保持高体温的方法叫gigantothermy，所以空格处应该是对应到前面的体积大。另外也后面举了例子，“这招大象、鲸、甚至可能大恐龙也用”，举出的都是大型动物，所以猜出bulk是“大”。effort和strength接近，activity不合文意。

Question 6 of 13

正确答案：B

解析：指代题。结合句意理解，原句说的是：当血液流过龟的脚蹼时，血液温度会降低，当____回去时，可能会带来降低身体温度的风险。依据意义，只能是流经脚蹼的血液再流回去时，会降低这种龟的体温。

Question 7 of 13

正确答案：B

解析：通过题干关键词stay warm对应到第四段前几句：巨温法还不足以让棱皮龟保暖，鲸类也是需要有厚厚的绝缘脂(脂肪)来补充维持体温，棱皮龟没有鲸鱼那样的脂肪，但是它们有厚且含油的皮肤，皮肤下有一层纤维，而脂肪组织就在这个纤维层下面。说明这个厚且含油的皮肤就是起到让棱皮龟保暖的作用的。选B。

Question 8 of 13

正确答案：A

解析：原句的结构是：一个…的血管离另一个…的血管近，因此热量可以转移，所以答案A正确。B选项within这个状语意义与原句不符，这一过程并不是封闭在鳍部里发生的，只是流经鳍部的；原文说是一个血管离另一个血管近，不是一只乌龟靠近另一只乌龟，C完全不合文意；原文说两个血管靠的近，不是D说的“鳍部靠近身体”；几个错误答案都偷换了原文的概念。

Question 9 of 13

正确答案：B

解析：修辞目的题，修辞点所在的句子开头就说this is the same…，说明老式蒸汽式暖气片有着与前面countercurrent exchange system类似的装置，当水流经这些盘绕的管子时，热量进行了交换。这里举出老式蒸汽式暖气片的例子，是为了与前面的逆流交换系统做一个类比，进一步说明它的工作原理。

Question 10 of 13

正确答案：C

解析：course做动词，意为快速地流动。因此选C。另外通过前后文的类比关系也能推出词意。前一句说的是棱皮龟流动的血液间距很近，便于热量交换，同样，水也是在盘管里流动交换热量。

Question 11 of 13

正确答案：C

解析：以young leatherback turtle做关键词定位至最后一段第二句，注意第二句中的hatchling与关键词同义。原文提到仔龟因为身形太小，尽管有countercurrent exchange system也不能保暖，所以答案是C。A说“没有逆流交换系统”与原文相反；B选项与原文倒数第二句相反；D与原文第三句信息不符，原文说到不知道什么时候它才能变成warm-blooded mode。

Question 12 of 13

正确答案：D

解析：三个过渡点，名词additional means，代词these和连词however。这道题最有用的过渡点是第一个，因为additional means就说明之前还有其他维持体温的方法，而直到D点之前文章都在说gigantothermy这种靠体积维持体温的方法，所以答案是D。此外，A和B之后的it都指代前面的gigantothermy，说明这两点衔接紧密，不能插入任何句子；D点后的muscular activity是与之前不同的一种方法，进一步证明D正确。

Question 13 of 13

正确答案：BDE

解析：B对应到第五段第一句：棱皮龟利用逆流交换系统，使得从脚蹼流回体内的血液温度变高。D对应到第三段前两句：棱皮龟有三种方法保持体温，第一种就是大小。后面还解释了棱皮龟体积大，降温慢。E选项对应第四段前三句：巨温法还不足以让棱皮龟保暖，鲸类也是需要有厚厚的绝缘脂(脂肪)来补充维持体温，棱皮龟没有鲸鱼那样的脂肪，但是它们有厚且含油的皮肤。所以它这层皮肤相当于鲸类的脂肪。

A错在后半句，与第一段最后一句信息不符；C错在原文第四段虽然提到脚蹼的形状，但原文主要说的是它的形状薄且呈叶片状，因此容易变凉，是不利于棱皮龟保暖的，与C信息相反。F选项与最后一段信息不符，最后一段只是提到：幼年棱皮龟仅仅通过皮肤隔绝、逆流循环系统是不足以保暖的，但没有提到他们的存活问题。

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