Potential Alternative Source of Energy-cellulose托福聽力原文翻譯及問題答案

Potential Alternative Source of Energy-cellulose托福聽力原文翻譯及問題答案

一、Potential Alternative Source of Energy-cellulose托福聽力原文：

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

FEMALE PROFESSOR:Your reading for today's class was about potential alternative sources of energy.So one thing I want to do today is consider one of those potential energy sources,cellulose.

Who can tell us what cellulose is?Allen?

MALE STUDENT:Cellulose,yeah,it's a tough organic molecule…made of simple sugars.It's found in the walls of all plant cells…in grass,trees…all plants,and,well…there's more cellulose than any other organic molecule on Earth.

FEMALE PROFESSOR:Good.It's also a potential tremendous source of energy,in part because there's so much of it.

Now,many organisms live on the energy they derive from consuming cellulose—like many species of bacteria…or cows and goats.Cows and goats have evolved highly specialized digestive systems that allow them to metabolize cellulose.

MALE STUDENT:But it's hard for most species to process cellulose?

FEMALE PROFESSOR:Yes,and it's been very hard to develop a controlled way to process cellulose in a lab,so that we can use the energy that's stored in it.It needs to be converted into ethanol.

Let me explain….Ethanol is a liquid,a kind of alcohol that is derived from processing sugars from plants,often corn,and it can be used as fuel.Many researchers believe it is the key to ending the reliance on gasoline.

The problem is that the amount of energy we get from corn-based ethanol isn't much more than the amount of energy that gets put into making it,so it's not really worth it.Tina?

FEMALE STUDENT:But ethanol made from cellulose is different?

FEMALE PROFESSOR:Yes—it's possible to get a vastly better energy yield on cellulose-based,or cellulosic,ethanol.

FEMALE STUDENT:OK,so why don't we just use cellulosic ethanol?

FEMALE PROFESSOR:Well,the problem is that the current method for processing cellulose into ethanol is very expensive and can't be done on a large scale.

See,currently,there are two key steps in the process.

The first is breaking the cellulose down into sugars.This is done with an enzyme,a specific type of protein.And second,after the enzyme has broken down the cellulose,yeast and other microorganisms—microbes—are added to ferment those sugars into cellulosic ethanol.

Thing is,though,we're not too good at producing the enzymes that break down cellulose.Those proteins are very difficult to make,to just assemble in a lab,so usually we extract enzymes from microorganisms that produce them naturally.Unfortunately,this is slow,expensive,and just not very efficient

MALE STUDENT:So are they trying to develop a better way to make enzymes?

FEMALE PROFESSOR:Actually,there's a company that thinks they can do better than that.It'd be more efficient,and therefore cheaper,to combine the two steps I mentioned into one.That is,have a single organism that breaks down cellulose and then produces ethanol.So,what this company is doing is searching around the world and gathering naturally occurring microorganisms that do both things.

I mean,the best key to unlocking the power of cellulose may well lie in a rare species of bacteria or yeast in a jungle somewhere.

So,researchers at this company have discovered some microorganisms that process cellulose and produce ethanol.Now,they’re working on enhancing,improving,certain natural characteristics of these microorganisms…manipulating them with sophisticated technology…to make them work even more efficiently.The goal,which seems to definitely be within reach,is to design and engineer a superbug,a specific kind of microbe,that makes cheap,commercial production of cellulosic ethanol a real possibility.

二、Potential Alternative Source of Energy-cellulose托福聽力中文翻譯：

旁白：在生物課上聽一節(jié)課的一部分。

女教授：你今天課上讀的是關(guān)于潛在的替代能源。所以我今天想做的一件事就是考慮一種潛在的能源，纖維素。

誰能告訴我們纖維素是什么？艾倫？

男生：纖維素，是的，它是一種堅硬的有機(jī)分子……由單糖組成。它存在于所有植物細(xì)胞的壁中……在草、樹……所有植物中……而且，嗯……纖維素比地球上任何其他有機(jī)分子都多。

女教授：好。它也是一種潛在的巨大能源，部分原因是它的儲量太大了。

現(xiàn)在，許多生物體像許多細(xì)菌物種或奶牛和山羊一樣，依靠消耗纖維素產(chǎn)生的能量生存。奶牛和山羊已經(jīng)進(jìn)化出高度專業(yè)化的消化系統(tǒng)，使它們能夠代謝纖維素。

男學(xué)生：但大多數(shù)物種很難加工纖維素？

女教授：是的，很難在實(shí)驗室里開發(fā)出一種可控的纖維素加工方法，這樣我們就可以利用其中儲存的能量。它需要轉(zhuǎn)化為乙醇。

讓我解釋一下…。乙醇是一種液體，是一種從植物（通常是玉米）加工糖中提取的乙醇，可以用作燃料。許多研究人員認(rèn)為，這是結(jié)束對汽油依賴的關(guān)鍵。

問題是，我們從玉米乙醇中獲得的能量并不比制造乙醇所需的能量多多少，所以這并不值得。蒂娜？

女學(xué)生：但是由纖維素制成的乙醇是不同的？

女教授：是的，基于纖維素或纖維素的乙醇有可能獲得更好的能源產(chǎn)量。

女生：好吧，那我們?yōu)槭裁床恢苯佑美w維素乙醇呢？

女教授：問題是，目前將纖維素加工成乙醇的方法非常昂貴，無法大規(guī)模進(jìn)行。

請參閱，目前，該過程有兩個關(guān)鍵步驟。

首先是將纖維素分解成糖。這是用一種特定類型的蛋白質(zhì)酶來完成的。其次，在酶分解纖維素后，添加酵母和其他微生物，將這些糖發(fā)酵成纖維素乙醇。

但問題是，我們不太擅長產(chǎn)生分解纖維素的酶。這些蛋白質(zhì)很難制造，很難在實(shí)驗室組裝，所以我們通常從自然產(chǎn)生它們的微生物中提取酶。不幸的是，這樣做速度慢、成本高，而且效率不高

男學(xué)生：那么他們是不是在嘗試開發(fā)一種更好的酶的制造方法？

女教授：事實(shí)上，有一家公司認(rèn)為他們可以做得更好。將我提到的兩個步驟合并為一個步驟會更有效，因此更便宜。也就是說，只有一種有機(jī)體能分解纖維素，然后產(chǎn)生乙醇。所以，這家公司正在全球范圍內(nèi)進(jìn)行搜索，并收集自然產(chǎn)生的微生物，這兩種微生物都起作用。

我的意思是，釋放纖維素能量的最佳鑰匙可能就在某個叢林中的稀有細(xì)菌或酵母物種中。

因此，該公司的研究人員發(fā)現(xiàn)了一些加工纖維素和生產(chǎn)乙醇的微生物?，F(xiàn)在，他們正致力于增強(qiáng)、改善這些微生物的某些自然特性……用尖端技術(shù)操縱它們……使它們更有效地工作。這一目標(biāo)似乎很容易實(shí)現(xiàn)，即設(shè)計和制造一種超級細(xì)菌，一種特殊的微生物，使纖維素乙醇的廉價商業(yè)化生產(chǎn)成為可能。

三、Potential Alternative Source of Energy-cellulose托福聽力問題：

Q1:1.What is the discussion mainly about?

A.Advantages of cellulose over traditional sources of fuel.

B.A recent study about microorganisms that process cellulose.

C.Some newly discovered characteristics of cellulose.

D.Challenges involved in converting cellulose into fuel.

Q2:2.According to the speakers,why is cellulose such a significant potential source of energy?

A.Because it is so abundant in nature.

B.Because it is so easily created in a lab.

C.Because its enzymes have so many uses.

D.Because it can be processed in just a few steps.

Q3:3.What is the professor's opinion about corn-based ethanol?

A.She thinks using it in motor vehicles may harm the environment.

B.She thinks it is not an energy-efficient alternative to gasoline.

C.She thinks it will eventually become cheaper to produce.

D.She thinks researchers should invest more in its development.

Q4:4.The professor describes the current method for producing cellulose ethanol.What are the two important steps she mentions?[Click on 2 answers.]

A.Yeast is added to cellulose to create an enzyme.

B.An enzyme breaks down cellulose into sugars.

C.Microorganisms ferment sugars into alcohol.

D.Ethanol is extracted from certain microorganisms.

Q5:5.What does the professor imply about a superbug?[Click on 2 answers.]

A.It will be an altered version of a naturally occurring organism.

B.It was discovered as a result of looking for new sources of cellulose.

C.It may contribute to the development of an efficient way to produce ethanol

D.It may produce many kinds of alternative fuels.

Q6:6.Why does the professor says this:

A.To emphasize the necessity of working to preserve rare species.

B.To suggest that the company will never find what it is looking for.

C.To emphasize that bacteria that break down cellulose are too rare to be useful.

D.To indicate that she endorses the company's strategy.

四、Potential Alternative Source of Energy-cellulose托福聽力答案：

A1:正確答案：D

A2:正確答案：A

A3:正確答案：B

A4:正確答案：BC

A5:正確答案：AC

A6:正確答案：D

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