North American Wood Frog托福听力原文翻译及问题答案

North American Wood Frog托福听力原文翻译及问题答案

一、North American Wood Frog托福听力原文：

Narrator:Listen to part of a lecture in a biology class.Female Professor:Well,it's finally looking like spring is arriving—the last of the winter snow will be melting away in a few days.So before we close today,I thought I'd mention,uh,a biological event that's part of the transition from winter to spring…something you can go outside and watch,if you have some patience.There's a small creature that lives in this area—you've probably seen it:it's the North American wood frog…Now the wood frog’s not that easy to spot,since it stays pretty close to the ground,under leaves and things,and it blends in really well with its background,as you can see.But they’re worth the effort,because they do something very unusual—something you might not have even thought possible…OK,North American wood frogs live over a very broad territory,or range—they're found all over the northeastern United States,and all through Canada and Alaska—even inside the Arctic Circle.No other frog is able to live that far north.But wherever they live,once the weather starts to turn cold,and the temperatures start to drop below freezing—as soon as the frog even touches an ice crystal or a bit of frozen ground…well,it begins to freeze.Yes,Jimmy?You look a bit taken aback…Male Student:Wait…you mean,it's still alive,but it freezes?Solid?

Female Professor:Well,almost.Ice forms in all the spaces outside cells,but never within a cell.Male Student:But…then,how does its heart beat?

Female Professor:It doesn't.Male Student:But—how can it do…Female Professor:How can it do such a thing?Well,that first touch of ice apparently triggers a biological response inside the frog,that first of all starts drawing water away from the center of its body.So the middle part of the frog,its internal organs—its heart,lungs,liver—these start getting drier and drier,while the water that's being pulled away is forming a puddle around the organs,just underneath the skin.

And then that puddle of water starts to freeze.OK,up to now the frog's heart is still beating,right?Slower and slower,but….And in those last few hours before it freezes,it distributes glucose—a blood sugar—throughout its body,its circulatory system.Sort of acts like an antifreeze…

Male Student:A solution of antifreeze,like you put in your car in the winter?

Female Professor:Well,you tell me.In frogs,the extra glucose makes it harder for the water inside the cells to freeze,so the cells stay just slightly wet—enough so that they can survive the winter.Then after that,the heart stops beating altogether.So,is that the same?

Male Student:I don’t really know,but uh…how long does it stay that way?

Female Professor:Well,it could be days or even months—all winter,in fact.But,um,see,the heart really doesn't need to do any pumping now,because the blood is frozen too.Male Student:I just…I guess I just don't see how it isn't—y'know,clinically dead.Female Professor:Well,that's the amazing thing.And how it revives is pretty amazing too.After months without a heartbeat,springtime comes around again,the Earth starts to warm up,and suddenly one day—ping!A pulse—followed by another one,then another,until—maybe ten,twelve hours later,the animal is fully recovered.Male Student:And—does the,uh,thawing process have some kind of trigger as well?Female Professor:Well,we're not sure,actually.The peculiar thing is,even though the sun is warming the frog up on the outside,its insides thaw out first—the heart and brain and everything.But somehow,it all just happens that way every spring.

Male Student:And after they thaw?Does it affect them?Like their life span?Female Professor:Well,hmm…we really don't know a lot about how long a wood frog normally lives—probably just a few years.But there's no evidence that the freezing process affects its longevity.It does have some other impacts,though.In studies we've found that,when it comes to reproduction,freezing diminishes the mating performance of males:

after they’ve been frozen,and thawed of course,they don't seem quite as vocal,they move slower—and they seem to have a harder time recognizing a potential mate.So if a male frog could manage not to go through this freezing cycle,he'd probably have more success at mating.

二、North American Wood Frog托福听力中文翻译：

旁白：在生物课上听一节课的一部分。女教授：看来春天终于来了，冬天的最后一场雪几天后就会融化了。所以在我们今天结束之前，我想我应该提到，呃，一个生物学事件，它是从冬天到春天过渡的一部分……如果你有耐心的话，你可以到外面看。有一种小生物生活在这个地区，你可能见过它：它是北美林蛙……现在林蛙不那么容易被发现，因为它离地面很近，在树叶和其他东西下面，而且它与背景很好地融合在一起，正如你所见。但是他们值得付出努力，因为他们做了一些非常不寻常的事情，你可能甚至没有想到这是可能的……好吧，北美树蛙生活在一个非常广阔的领土上，或者说分布范围很广，它们遍布美国东北部，遍布加拿大和阿拉斯加，甚至在北极圈内。没有其他青蛙能生活在那么遥远的北方。但无论它们住在哪里，一旦天气开始变冷，当青蛙接触到冰晶或一小块冻土时，温度就开始降到零度以下……嗯，它开始结冰了。什么事，吉米？你看起来有点吃惊……男学生：等等……你是说，它还活着，但它冻结了？固体

女教授：嗯，差不多了。冰在细胞外的所有空间都会形成，但绝不会在细胞内形成。男学生：但是……那么，它的心跳是怎样的？

女教授：不是。男学生：但它怎么能做……女教授：它怎么能做这样的事？嗯，第一次接触到冰显然会触发青蛙体内的生物反应，首先会将水从身体中心抽走。所以青蛙的中部，内脏，心脏，肺，肝脏开始变得越来越干燥，而被抽走的水在器官周围，皮肤下面形成了一个水坑。

然后那滩水开始结冰。好吧，到目前为止，青蛙的心脏还在跳动，对吗？越来越慢，但是…。在冻结前的最后几个小时，它将葡萄糖（一种血糖）分配到全身和循环系统。有点像防冻剂…

男生：防冻液的解决方案，比如你在冬天把它放在车里？

女教授：好吧，你告诉我。在青蛙身上，额外的葡萄糖使细胞内的水更难冻结，因此细胞保持略微湿润，这样就可以在冬天存活下来。然后，心脏停止跳动。那么，这是一样的吗？

男学生：我真的不知道，但是，呃……这种情况会持续多久？

女教授：事实上，整个冬天可能是几天甚至几个月。但是，嗯，看，心脏现在真的不需要做任何泵送，因为血液也冻结了。男学生：我只是……我想我只是不明白为什么它不是——你知道，临床死亡。女教授：好吧，这真是太神奇了。它是如何复苏的，也非常令人惊讶。几个月没有心跳，春天又来了，地球开始变暖，突然有一天，砰砰！一个脉冲接着是另一个脉冲，然后是另一个脉冲，直到大约十、十二个小时后，动物完全康复。男学生：嗯，解冻过程也有某种触发因素吗？女教授：嗯，实际上我们不确定。奇怪的是，尽管太阳正在使青蛙的外部变暖，但它的内部首先融化了心脏、大脑和一切。但不知何故，每年春天都是这样。

男学生：解冻后呢？这会影响他们吗？比如他们的寿命？女教授：嗯……我们真的不太清楚一只林蛙通常能活多久，可能只有几年。但没有证据表明冷冻过程会影响其寿命。不过，它确实有其他一些影响。在研究中，我们发现，在生殖方面，冷冻会降低雄性的交配性能：

当然，在它们被冷冻、解冻后，它们的声音似乎就不那么响亮了，它们的动作也变慢了，而且它们似乎很难识别出一个潜在的伴侣。因此，如果雄蛙能设法不经历这种冰冻循环，那么它的交配可能会更成功。

三、North American Wood Frog托福听力问题：

Q1:1.What is the main purpose of the lecture?

A.To explain the biological advantages of a physical change that occurs in North American wood frogs

B.To explain why the North American wood frog's habitat range has expanded

C.To describe the functioning of the circulatory system of the North American wood frog

D.To introduce students to an unusual phenomenon affecting North American wood frogs

Q2:2.Why does the professor first mention the arrival of spring?

A.To encourage students to look for thawing wood frogs

B.To point out the time period when frogs begin mating

C.To explain why the class will soon be doing experiments with wood frogs

D.To emphasize the speed of the thawing process

Q3:3.What happens to a wood frog as it begins to freeze?

A.Blood is concentrated in the center of its body.

B.Blood stops producing sugar.

C.Water moves out of its internal organs.

D.Water from just beneath the skin begins to evaporate.

Q4:4.What are two points the professor makes about the thawing process of the wood frog?[Click on 2 answers.]

A.The thawing process is not fully understood.

B.The thawing process takes longer than the freezing process.

C.The frog's internal organs thaw before its outer skin thaws.

D.Thawing occurs when the frog's heart begins pumping glucose through its body.

Q5:5.What impact does freezing have on some thawed wood frogs?

A.It increases their reproductive success.

B.It decreases their life span.

C.It causes them to be more vocal and active.

D.It reduces their ability to recognize potential mates.

Q6:6.What does the professor imply when she says this:

A.She wants the student to clarify his question.

B.She wants the student to draw his own conclusions.

C.She thinks the student does not understand how car antifreeze works.

D.She thinks the student has misunderstood her point.

四、North American Wood Frog托福听力答案：

A1:正确答案：D

A2:正确答案：A

A3:正确答案：C

A4:正确答案：AC

A5:正确答案：D

A6:正确答案：B

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