Jarosite托福听力原文翻译及问题答案

Jarosite托福听力原文翻译及问题答案

一、Jarosite 托福听力原文：

NARRATOR: Listen to part of a lecture in an astronomy class.MALE PROFESSOR: There's been a lot of talk recently about life on Mars, at the level of microorganisms anyway, mainly because of a few important discoveries and inventions.

For example, one major discovery was that at one point water was present on Mars. How do we know? Well, in 2004, an exploration robot discovered jarosite there.Jarosite is a yellowish brown mineral with a crystalline structure that's also found on Earth. It contains iron, potassium and hydroxide.The interesting thing is that on Earth at least it needs highly acidic water to form.So we've got water or had it at one point. And since most planetary scientists believe that water is essential to life, the presence of jarosite means that one prerequisite for life was once present on Mars.But there's another thing about jarosite. One step in its formation on Earth involves microorganisms; they actually speed up the formation of jarosite dramatically. Now, theoretically it is possible for jarosite to form without the help of biological life forms. But we don't really know for sure if this happens 'cause, well, because every corner of Earth has some form of biological life.

But jarosite on Earth incorporates all kinds of microorganisms into its crystalline structure. So it's possible that if the jarosite on Mars was also formed with the help of microorganisms, we might be able to detect remnants of them in the samples we find. And we have instruments now that will enable us to try to do this. For example, there's a new instrument called the microfabricated organic analyzer, or M.O.A.The organic analyzer is an amazing tool. It will be able to collect soil samples and analyze them right there on Mars, pure, untouched samples.It will let us eliminate the risk we would take of contaminating the samples if they were brought back to Earth.And what they'll look for specifically in the soil is amino acids.Amino acids, as you may know, are the building blocks of proteins. In fact, there are twenty standard amino acids involved in making proteins and lots more that aren't.

And here's the important thing. Amino acids are what we call handed.They can exist in two forms, which are mirror images of each other like hands. Right and left hands have the same number of fingers in the same order plus one thumb.But right and left hands are not the same; they are mirror images. Well, like hands, amino acids can be right or left-handed. And the twenty that make up the proteins on Earth are all left-handed.Now, one reason the M.O.A., the organic analyzer is so impressive is that it tests not just for the presence of amino acids but also for the handedness of amino acids. If amino acids are found, it would be especially interesting if they show a prevalence of one type of handedness, either left, like amino acids on Earth, or right.

See, other physical processes in space, processes that don't involve living organisms, can create amino acids.But the ones synthesized through abiotic processes, which is to say not involving microorganisms, occur in equal numbers of right- and left-handed.

So, a prevalence of left-handed amino acids would indicate they were biological in origin, which would be amazing! A prevalence of right-handed ones—well, that would be really amazing!! Because the organisms that created them would be unlike anything we have on Earth, which produce only left-handed ones.

二、Jarosite 托福听力中文翻译：

旁白：在天文学课上听一节课的一部分。男教授：最近有很多关于火星生命的讨论，从微生物的角度来说，主要是因为一些重要的发现和发明。

例如，一项重大发现是火星上曾一度存在水。我们怎么知道？2004年，一个探测机器人在那里发现了黄钾铁矾。黄钾铁矾是一种黄褐色矿物，其晶体结构也存在于地球上。它含有铁、钾和氢氧化物。有趣的是，至少在地球上，它需要高酸性的水才能形成。所以我们有水或者曾经有过水。由于大多数行星科学家认为水对生命至关重要，黄钾铁矾的存在意味着火星上曾经存在过生命的先决条件。但关于jarosite还有另一件事。它在地球上形成的一个步骤涉及微生物；它们实际上大大加速了黄钾铁矾的形成。现在，理论上黄钾铁矾可以在没有生物生命形式帮助的情况下形成。但我们并不确定这种情况是否会发生，因为地球的每个角落都有某种形式的生物。

但地球上的黄钾铁矾将各种微生物结合到其晶体结构中。因此，如果火星上的黄钾铁矾也是在微生物的帮助下形成的，我们就有可能在我们发现的样本中检测到黄钾铁矾的残余物。我们现在有了能够使我们努力做到这一点的工具。例如，有一种新的仪器叫做微加工有机分析仪，或称M.O.a。有机分析仪是一种神奇的工具。它将能够在火星上采集土壤样本并进行分析，这些样本是纯净的、未接触过的。这将使我们消除如果样品被带回地球，我们将面临的污染风险。他们会在土壤中特别寻找氨基酸。你可能知道，氨基酸是蛋白质的组成部分。事实上，有20种标准氨基酸参与蛋白质的合成，还有更多的氨基酸没有参与。

这是重要的一点。氨基酸就是我们所说的手。它们可以以两种形式存在，就像手一样，是彼此的镜像。右手和左手有相同顺序的相同数量的手指加上一个拇指。但右手和左手不一样；它们是镜像。就像手一样，氨基酸可以是右手的也可以是左手的。地球上组成蛋白质的20个都是左手的。现在，有机分析仪给人留下深刻印象的一个原因是，它不仅检测氨基酸的存在，还检测氨基酸的利手性。如果氨基酸被发现，如果它们显示出一种惯用手的流行，无论是左撇子，就像地球上的氨基酸，还是右撇子，那将是特别有趣的。

看，太空中的其他物理过程，不涉及生物体的过程，可以产生氨基酸。但是通过非生物过程合成的，也就是说不涉及微生物的，以相同数量的右手和左手出现。

因此，左旋氨基酸的普遍存在将表明它们是生物起源，这将是惊人的！惯用右手的人很普遍哦，那真是太神奇了！！因为创造它们的有机体与我们地球上的任何生物都不一样，地球上只有左手生物。

三、Jarosite 托福听力问题：

Q1:1.What is the lecture mainly about?

A. Evidence proving that water was once present on Mars

B. Scientific analyses currently being done on mineral samples from Mars

C. Recent developments that could help determine whether life ever existed on Mars

D. An approach to determining whether amino acids on Earth originated on Mars

Q2:2.What was discovered on Mars that suggests water once existed there?

A. Microorganisms that can form only in the presence of water

B. A mineral that can form only in the presence of water

C. Proteins that have the same structure as proteins found on Earth

D. Large deposits of iron and potassium that can form only in the presence of water

Q3:3.How might jarosite found on Mars differ from jarosite found on Earth?

A. Mars jarosite and Earth jarosite might have been created by different processes.

B. Mars jarosite might have been formed without water.

C. Mars jarosite might not contain as much iron or potassium as Earth jarosite.

D. Mars jarosite might be more acidic than Earth jarosite.

Q4:4.According to the professor, what are two important capabilities of the microfabricated organic analyzer? [Click on 2 answers.]

A. It can accurately test for the presence of water.

B. It can analyze soil samples without returning them to Earth.

C. It can return soil samples back to Earth quickly.

D. It can determine the handedness of amino acids.

Q5:5.What point does the professor make about the twenty amino acids that occur in proteins on Earth?

A. They can be either right-handed or left-handed.

B. They were synthesized through abiotic processes.

C. They all have a crystalline structure.

D. They are all left-handed.

Q6:6.What would a prevalence of right-handed amino acids in mineral samples collected on Mars indicate?

A. That amino acids on Mars probably originated on Earth

B. That amino acids existed on Mars long before they existed on Earth

C. That a type of microorganism may have existed on Mars that is different from any on Earth

D. That left-handed amino acids are probably present in some minerals on Mars

四、Jarosite 托福听力答案：

A1:正确答案：C

A2:正确答案：B

A3:正确答案：A

A4:正确答案：BD

A5:正确答案：D

A6:正确答案：C