Endotherms And Ectotherms托福听力原文翻译及问题答案

Endotherms And Ectotherms托福听力原文翻译及问题答案

一、Endotherms And Ectotherms托福听力原文：

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托福听力中文翻译：

旁白：听生物课上的一节课。

女教授：那么，回顾一下……谁还记得动物是如何按照体温分类的？迈克？

男学生：嗯，吸热和放热？女教授：对！所有动物都被认为是吸热动物或放热动物。Therm：…意思是“热”。“吸热和放热的主要区别在于身体热量的来源。

因此，吸热的“endo”意思是“内部”-吸热的体温主要来自身体内部。它可以通过新陈代谢在体内产生自己的热量。外温热动物-“外温热”的意思是“外部的”-外温热生物主要从自身身体外部获取体温。这意味着，从它的环境。主要来自太阳辐射。所以我们有吸热动物-哺乳动物和鸟类属于这一类-和外温热动物，这几乎是所有其他动物…包括爬行动物，两栖动物，昆虫…现在，体温很重要。如果一只动物的环境变得非常热或非常冷，为了使它的体温保持在正常范围内，需要发生一些事情。在吸热状态下，这主要是生理性的。身体改变其产热速率。

好吧，人类是吸热的。当你的身体变得很冷时，它会自动做什么？男学生：颤抖？女教授：对，在颤抖。事实上，任何肌肉运动都会增加新陈代谢，这是一个在环境变冷时产生热量并保持体温升高的过程。

还有一种被称为棕色脂肪，像其他种类的脂肪一样，它储存三碘甲状腺原氨酸，但棕色脂肪是独特的，因为它在化学上产生大量热量，即使没有肌肉运动。这对气候较冷的小型哺乳动物尤其有益。当一只动物变得太热的时候，你有没有见过一只狗通过短呼吸来降温？而人类，我们出汗，当然，出汗，这也可以消除体温。这些也是自动的生理反应。是的，艾莉？女学生：所以在吸热学中，它不是关于行为……关于做事。女教授：嗯，你知道，人类可能会穿上冬衣或跳进游泳池，或者大象，大象可能会在外面暖和的时候泼冷水，但在大多数情况下，不会。与低温动物不同的是，不是我们吸热动物的行为使我们的温度保持在一定范围内。

女学生：那么，像青蛙这样的低温动物呢？他们一定也有新陈代谢。女教授：当然有。

只是低温动物的新陈代谢要低得多。我的意思是，吸热动物（比如老鼠）的代谢率至少是青蛙或蜥蜴等类似体型的外温动物的六到七倍。外热源在内部产生的热量几乎没有外热源多。因此，它的体温将趋于与周围环境的温度相等。这就是行为的原因。想象一只蜥蜴，好吗？生活在沙漠中。

沙漠晚上很冷，白天很热。那么蜥蜴是如何保持体温的呢？嗯，在寒冷的早晨，它可以去一个阳光明媚的地方躺在阳光下取暖，然后如果天气太热，它可以在阴凉处找到一个凉爽的地方。正是通过这种行为，像这种蜥蜴这样的低温动物才能调节体温。但是你把这只蜥蜴放在一个温度可控的房间里，然后逐渐降低温度，比如说，20度，当然，在这里，蜥蜴不能去躺在阳光下。那么会发生什么呢？男学生：嗯，蜥蜴的体温也会下降。女教授：对，这真的减缓了它的新陈代谢，这取决于温度。尽管体温下降了20度，但蜥蜴也能安然无恙地生存下来，当它再次升温时，情况也很好。低温动物可以做到这一点。

男学生：但是一个低温动物可能不会在温度太低的地方生存，对吗？女教授：听说过青蛙被北极熊追赶吗？男学生：没有。女教授：好了，你来了。同样情况下，同样温度的老鼠和蜥蜴正好相反。当温度下降时，老鼠的新陈代谢上升。像任何吸热动物一样，它开始产生更多的热量以保持体温稳定，就像在野外一样。

三、Endotherms And Ectotherms托福听力问题：

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托福听力答案：

A1:正确答案：B

A2:正确答案：C

A3:正确答案：D

A4:正确答案：C

A5:正确答案：D

A6:正确答案：A