Endotherms And Ectotherms托福聽力原文翻譯及問題答案

Endotherms And Ectotherms托福聽力原文翻譯及問題答案

一、Endotherms And Ectotherms托福聽力原文：

NARRATOR:Listen to part of a lecture in a biology class.

FEMALE PROFESSOR:So,to review....who remembers how animals are classified,in terms of body temperature?Mike?

MALE STUDENT:Um,endotherms and ectotherms?FEMALE PROFESSOR:Right!All animals are considered either endotherms or ectotherms."Therm:...that means"heat."And the main thing that distinguishes endotherms from ectotherms is the source of body heat.

So an endotherm—"endo"meaning"internal"—an endotherm's body heat mainly comes from inside its body.It can generate its own heat internally with its metabolism.And an ectotherm—"ecto"meaning"external"—an ectotherm gets its body heat mainly from outside its own body.Meaning,from its environment.Mostly from the sun's radiation.So we've got endotherms—mammals and birds are the classes that fall under this category—and ectotherms—that's pretty much everything else...including reptiles,amphibians,insects...Now,body temperature is important.And if an animal's environment gets very hot or very cold,something needs to happen in order for the animal to maintain its body temperature within its normal range.In endotherms,this is mostly physiological.The body changes its rate of heat production.

Okay,well,humans are endotherms.What does your body automatically do when it gets really cold?MALE STUDENT:Shiver?FEMALE PROFESSOR:Right,shivering.In fact,any muscle movement increases metabolism,the process that produces heat and keeps your body temperature up when your surroundings get cold.

And then there's what's known as brown fat,like other kinds of fat,it stores triiodothyronine,but brown fat is unique because it chemically produces lots of heat even without muscle movement.That's especially beneficial for small mammals in colder climates.And when an animal gets too hot,well,have you ever seen a dog cooling off by taking short,quick breaths?And humans,we sweat,of course,perspire,which also gets rid of body heat.These are automatic,physiological responses too.Yes,Allie?FEMALE STUDENT:So in endotherms,it's not really about behavior...about doing things.FEMALE PROFESSOR:Well,a human,you know,might put on a winter coat or jump in a swimming pool,or elephants,elephants might splash themselves with cold water when it's warm out,but for the most part,no.It's not what we endotherms do that keeps our temperatures within range,unlike ectotherms.

FEMALE STUDENT:Well,what about ectotherms,like frogs?They must have metabolism too.FEMALE PROFESSOR:Sure they do.

It's just that metabolism in ectotherms is so much lower.I mean,the metabolic rate of an endotherm—say a mouse—is at least six or seven times that of an ectotherm of a similar size like a frog or a lizard.An ectotherm doesn't generate nearly as much heat internally.So its body temperature will tend to equalize with the temperature of its surroundings.And that's where behavior comes in.Imagine a lizard,okay?living in the desert.

Now,a desert gets very cold at night and very hot during the day.So what does the lizard do to maintain its body temperature?Well,on a cold morning,it can warm itself by going to a sunny spot and lying in the sun,and later if it gets too hot,it can seek out a cool place in the shade.It's by means of such behavior that an ectotherm like this lizard regulates its temperature.But you put that same lizard in a temperature controlled chamber and gradually drop the temperature,say,20 degrees,and here,of course,the lizard can't go off to lie in the sun.So what happens?MALE STUDENT:Well,the lizard's body temperature drops too.FEMALE PROFESSOR:Right,and this really slows down its metabolism,which depends on temperature.Even that 20 degrees drop in body temperature though,the lizard can survive that no problem,and come out just fine when it warms up again.Ectotherms can do that.

MALE STUDENT:But an ectotherm probably wouldn't survive in a place where the temperatures got too low,right?FEMALE PROFESSOR:Ever heard of a frog being chased by a polar bear?MALE STUDENT:No.FEMALE PROFESSOR:Well,there you are.Now a mouse in the same situation,in the same temperature chamber,is just the opposite of the lizard.When the temperature goes down,the mouse's metabolism goes up.Like any endotherm,it starts producing more heat to keep its body temperature stable,same as it would do outside in a field.

二、Endotherms And Ectotherms托福聽力中文翻譯：

旁白：聽生物課上的一節(jié)課。

女教授：那么，回顧一下……誰還記得動物是如何按照體溫分類的？邁克？

男學生：嗯，吸熱和放熱？女教授：對！所有動物都被認為是吸熱動物或放熱動物。Therm：…意思是“熱”?！拔鼰岷头艧岬闹饕獏^(qū)別在于身體熱量的來源。

因此，吸熱的“endo”意思是“內(nèi)部”-吸熱的體溫主要來自身體內(nèi)部。它可以通過新陳代謝在體內(nèi)產(chǎn)生自己的熱量。外溫熱動物-“外溫熱”的意思是“外部的”-外溫熱生物主要從自身身體外部獲取體溫。這意味著，從它的環(huán)境。主要來自太陽輻射。所以我們有吸熱動物-哺乳動物和鳥類屬于這一類-和外溫熱動物，這幾乎是所有其他動物…包括爬行動物，兩棲動物，昆蟲…現(xiàn)在，體溫很重要。如果一只動物的環(huán)境變得非常熱或非常冷，為了使它的體溫保持在正常范圍內(nèi)，需要發(fā)生一些事情。在吸熱狀態(tài)下，這主要是生理性的。身體改變其產(chǎn)熱速率。

好吧，人類是吸熱的。當你的身體變得很冷時，它會自動做什么？男學生：顫抖？女教授：對，在顫抖。事實上，任何肌肉運動都會增加新陳代謝，這是一個在環(huán)境變冷時產(chǎn)生熱量并保持體溫升高的過程。

還有一種被稱為棕色脂肪，像其他種類的脂肪一樣，它儲存三碘甲狀腺原氨酸，但棕色脂肪是獨特的，因為它在化學上產(chǎn)生大量熱量，即使沒有肌肉運動。這對氣候較冷的小型哺乳動物尤其有益。當一只動物變得太熱的時候，你有沒有見過一只狗通過短呼吸來降溫？而人類，我們出汗，當然，出汗，這也可以消除體溫。這些也是自動的生理反應(yīng)。是的，艾莉？女學生：所以在吸熱學中，它不是關(guān)于行為……關(guān)于做事。女教授：嗯，你知道，人類可能會穿上冬衣或跳進游泳池，或者大象，大象可能會在外面暖和的時候潑冷水，但在大多數(shù)情況下，不會。與低溫動物不同的是，不是我們吸熱動物的行為使我們的溫度保持在一定范圍內(nèi)。

女學生：那么，像青蛙這樣的低溫動物呢？他們一定也有新陳代謝。女教授：當然有。

只是低溫動物的新陳代謝要低得多。我的意思是，吸熱動物（比如老鼠）的代謝率至少是青蛙或蜥蜴等類似體型的外溫動物的六到七倍。外熱源在內(nèi)部產(chǎn)生的熱量幾乎沒有外熱源多。因此，它的體溫將趨于與周圍環(huán)境的溫度相等。這就是行為的原因。想象一只蜥蜴，好嗎？生活在沙漠中。

沙漠晚上很冷，白天很熱。那么蜥蜴是如何保持體溫的呢？嗯，在寒冷的早晨，它可以去一個陽光明媚的地方躺在陽光下取暖，然后如果天氣太熱，它可以在陰涼處找到一個涼爽的地方。正是通過這種行為，像這種蜥蜴這樣的低溫動物才能調(diào)節(jié)體溫。但是你把這只蜥蜴放在一個溫度可控的房間里，然后逐漸降低溫度，比如說，20度，當然，在這里，蜥蜴不能去躺在陽光下。那么會發(fā)生什么呢？男學生：嗯，蜥蜴的體溫也會下降。女教授：對，這真的減緩了它的新陳代謝，這取決于溫度。盡管體溫下降了20度，但蜥蜴也能安然無恙地生存下來，當它再次升溫時，情況也很好。低溫動物可以做到這一點。

男學生：但是一個低溫動物可能不會在溫度太低的地方生存，對嗎？女教授：聽說過青蛙被北極熊追趕嗎？男學生：沒有。女教授：好了，你來了。同樣情況下，同樣溫度的老鼠和蜥蜴正好相反。當溫度下降時，老鼠的新陳代謝上升。像任何吸熱動物一樣，它開始產(chǎn)生更多的熱量以保持體溫穩(wěn)定，就像在野外一樣。

三、Endotherms And Ectotherms托福聽力問題：

Q1:1.What do the speakers mainly discuss?

A.Internal processes that help animals maintain constant metabolic rates.

B.Differences in how animals regulate their body temperatures.

C.Behaviors that help some animal species survive in extreme environments.

D.The difficulty of determining whether an animal is an endotherm or an ectotherm.

Q2:2.According to the professor,what is distinctive about brown fat?

A.It produces large amounts of triglyceride.

B.It provides fuel for muscle movement.

C.It produces heat without muscle movement.

D.It insulates internal organs from the cold.

Q3:3.Why does the professor mention elephants?

A.To contrast them with small animals that live in extremely cold environments.

B.To show an important behavioral difference between two mammal species.

C.To emphasize that body size helps determine an animal's metabolic rate.

D.To indicate that endotherms may use behavior to help regulate body temperature.

Q4:4.What does the professor emphasize about the metabolic rate of ectotherms?

A.It is regulated by taking short,quick breaths.

B.It varies throughout the day.

C.It is much slower than the metabolic rate of endotherms.

D.It increases to help the animals survive a sudden drop in temperature.

Q5:5.What happens to an ectotherm in a temperature chamber?

A.It regulates its temperature by behaving in certain ways.

B.It shivers when the chamber's temperature is lowered.

C.Its metabolism remains unchanged.

D.Its body temperature matches the temperature inside the chamber.

Q6:6.Why does the professor says this:

A.To indicate that the student's assertion is correct.

B.To introduce a fact she thinks will surprise the student.

C.To point out the effectiveness of the frog's defense mechanisms.

D.To find out what the student knows about extreme environments.

四、Endotherms And Ectotherms托福聽力答案：

A1:正確答案：B

A2:正確答案：C

A3:正確答案：D

A4:正確答案：C

A5:正確答案：D

A6:正確答案：A

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