『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 42 Lec 3听力练习：What is the lecture mainly about?原文题目答案解析，TPO/Official 42 Lec 3听力原文范文音频翻译。

托福TPO/Official 42 Lec 3听力原文What is the lecture mainly about?【新东方在线】

旁白：听一段环境科学课程节选。

Narrator: Listen to part of a lecture in an environmental science class.

教授：当你们试着想象真菌的时候，你们可能马上就想到蘑菇破土而出的画面。

When you try to imagine a fungus, you'd probably picture a mushroom popping up out of the ground.

但是像那样的真菌……大部分这类真菌实际上都生长在地下。

But a fungus like that... most of it actually lives underground.

而且一般而言菌类总是土壤中重要的活跃成分。

And fungi in general are often an important active component of the soil.

真菌分泌酶进入土壤中，酶能够分解土壤里的有机物质。

A fungus secretes enzymes into the soil, enzymes that break down, decompose organic material in the soil.

这样一来，真菌就可以吸收掉这些材料得到营养了。

So the fungus can absorb this material and get nutrition.

但是，我觉得最有意思的是这个过程中真菌如何能够清理在土壤中的环境污染物。

But to me, what's most interesting about this process is how it may enable fungi to help clean up environmental pollution in the soil.

这在一定程度上要归功于它们细胞壁中一种叫做甲壳质的物质

And that's thanks in part to a substance in their cell walls called Chitin.

现在很多人都认为真菌和植物相关，但它们并不是。

Now a lot of people think fungi are related to plants, but they are not.

信不信由你，除了真菌，甲壳素含量丰富的另一种东西是昆虫、螃蟹等的外骨骼

Believe it or not, the only other place chitin is found in abundance is in the exoskeletons of insects, crabs and such.

这么看的话，真菌和昆虫的联系要比和植物更紧密。

So in this sense, fungi are more associated with insects than with any plant.

而丝状真菌细胞壁中的甲壳素是一种长丝状结构，细胞一个接一个地连接在一起

And the chitin in the cell walls of a filamentous fungus... a filament, of course, is a long thread-like structure, cells joined end to end.

丝状真菌在土壤和腐烂的植被中生长。

Filamentous fungi grow in soil and in decaying vegetation.

并且和它们名字一样，他们以丝的形式存在。

And as their name implies they exist as filaments.

虽然被视为微生物，但是来自一个单独的真菌菌丝可以扇形撒开， 占据森林土地中好几平方米甚至好几平方千米的面积。

And although regarded as microorganisms, filaments from a single fungus can fan out to occupy many square meters or even several square kilometers of forest floor.

它们巨大的表面积使得它们可以分解并吸收大量的营养物质,但除此之外，真菌还能带出土壤中可能存在的大量污染物质，尤其是一些重金属。

Their vast surface area allows them to break down and take in huge amounts of nutrients, but beyond that, the filaments also pull out of the soil a great deal of the pollution that might be in there, especially heavy metals.

这就是甲壳素发挥作用的地方。和真菌细胞壁中的一些其他物质一样，在一个我们称之为吸附的过程中，甲壳素和环境中的重金属形成了牢靠的化学键

And here is where chitin comes in, like some other substances in fungal cell walls, chitin forms strong chemical bonds to heavy metals in the environment, in a process we call adsorption.

好，不要把这点和吸收混淆了。吸收指的是一个物质被吸入到了细胞内，进入到细胞内部。

Now, don't confuse this with absorption, where a substance is absorbed into a cell, into the interior of a cell.

我的意思是这个过程也在这里发生。

但是吸附指的是粘在细胞的外表面上。

But adsorption means binding to the outer surface of the cell.

丝状真菌可以吸附有毒金属，把他们粘在巨大的菌丝网的表面，由此为大的土壤生态系统解毒。

And a filamentous fungus can adsorb toxic heavy metals, bind them to the surface of its enormous network of filaments, and thereby detoxify a large soil ecosystem.

重金属还是在那，但是大量的重金属也许会一直黏着在甲壳素中，黏在土壤里丝状真菌的细胞壁上， 而不是渗透到水系统中污染地下水，因此保持化学不活泼状态长达30年，甚至更久。

The heavy metals are still there, but instead of leaching into the water system and contaminating the water underground, large amounts of these metals may remain bound to the chitin, to the cell walls of filamentous fungi in the soil, and thus remain chemically inactive for as long as 30 years, perhaps longer.

事实上，即使这些真菌死了，我们还可以把丝状真菌的细胞壁用作过滤器。

In fact, we can actually use the cell walls of filamentous fungi as a filter, even after the fungi are dead.

举个例子，制药行业在实验室中培育了大量的丝状真菌，比如为了制造抗菌的盘尼西林，医药公司会培育盘尼西林菌群，在盘尼西林被萃取后，我们可以利用盘尼西林菌丝细胞壁中的角素来制造工业过滤器吸附重金属。

For example, the pharmaceutical industry grows filamentous fungi in large quantities in the lab, like to produce the antibiotic penicillin, the drug company grows the fungus penicillium, and after the penicillin is extracted, these dead penicillium filaments, we can use the chitin in their cell walls to make industrial filters to adsorb heavy metals.

我们可以把这些过滤器放进工业工序的废弃管道中，用他们来困住像汞和锌这样的重金属。

We can put these filters into waste pipes from industrial processes, and use the filters to trap heavy metals, like mercury and zinc.

然后再用化学方法提取重金属，并且这样的过滤器可以被一直重复使用下去。

Later, we can chemically extract the heavy metals and reuse the filter over and over.

现在我们回到把有毒金属吸到真菌内部的吸收过程，让我们把注意力转向蘑菇上。

Now going back to the absorption of toxic metals into the body of the fungus, let's turn our attention to mushrooms.

和其他真菌一样，蘑菇能够吸收大量的重金属。

Like other fungi, mushrooms can absorb large quantities of heavy metals.

事实上，（吸收重金属之后）它们所含的重金属可能是自己生长的土壤内重金属浓度的2.5倍。

In fact, they may contain up to two and a half times the concentration of toxic metals found in the soil they grow in.

所以，蘑菇，至少是我们能在地面上看到的那些蘑菇，我们把它们采摘下来，然后就把其中的污染物永久性的处理掉了。

So mushrooms, at least what we see above ground... we can potentially harvest them and then once for all safely dispose of the pollutants contained within them.

事实上， 为了永久的清洁，尤其是地下水系统，采摘蘑菇可能是最好的方法了。

In fact, to clean up, especially the groundwater system, permanently, harvesting mushrooms is probably the best way to go.

据我了解，因为某些原因，这个方法还没有被采用，但是我能很容易想象得出只是为了去除大的地下水系统中的毒素而培育蘑菇的场景。

For some reason, this hasn't happened yet as far as I know, but I can easily envision cultivating mushrooms for the sole purpose of detoxifying a large underground ecosystem.

What does the professor say about the way fungi get their food?

What two points does the professor make about chitin? Click on two answers.

What do adsorption and absorption in fungi have in common?

Why does the professor mention the antibiotic penicillin?

Listen to part of a lecture in an environmental science class
When you are trying to imagine a fungus, you probably picture a mushroom popping up out the ground. And think that’s it. But the fungus is like that, most of it actually lives under ground, and fungi in general are often an important active component of the soil. A fungus secretes enzymes into the soil, enzymes that breakdown, decompose organic materials in the soil, so the fungus can absorb this material and get nutrition. But to me, what’s most interesting about this process is how it mean enable fungi to help clean up environment pollution in the soil. And that thanks in part to a substance in their cell walls called chitin.
Now a lot of people think fungi are related to plants, but they are not. Believe it or not, the only other place chitin is found abundance is in the exoskeletons of insects, crabs, in such. So in this sense, fungi are more associated with insects than with any plant. Strange, uh?
And the chitin in the cell walls of the filamentous fungus. A filament is of course a long threadlike structure so strong at the end. Filamentous fungi grow in soil and vegetation, and as the name implies, they exist as filaments. And although regarded as microorganisms, filaments from a single fungus can find out to occupy many square meters, or even several square kilometers of farthest floor. Their vast surface area allows them to break down and takes in huge amount of nutrients. But beyond that, the filaments also pour out the soil a great deal of the pollution that might be in there, especially heavy metals.
And here is what chitin comes in. Like some other substances in fungus cell walls, chitin forms strong chemical bounds to heavy metals environment, in a process we call adsorption. Now don’t confuse this with absorption, where substances absorbed into a cell into the interior of a cell. I mean that’s happening here too. But adsorption means binding to the outer surface of the cell. And filamentous fungus can adsorb toxicant metals, binding them to the surface of enormous network of filaments. And thereby detoxify a large soil ecosystem. The heavy metals are still there, but instead of leaching into the water system and contaminating the water on the ground, large amount of these metals may remain bound to the chitin, to the cell walls of filamentous fungi in the soil. And thus remain chemically ineffective for as long as thirty years, perhaps longer.
In fact, we can actually use the cell walls of filamentous fungi as a filter, even after the fungi are dead. For example, the pharmaceutical industries grow filamentous fungi in large quantities in the lab. Like, to produce the antibiotic penicillin, the drug company grows the fungus Penicillium. And after the penicillin is extracted, these dead Penicillium filaments, we can use the chitin in the cell walls to make industrious filters to adsorb the heavy metals. We can put these filters in the waste pipes from industrial processes, and use the filters to trap metals like zinc. Later, we can chemically extract the heavy metals and reuse the filter over and over.
Now, going back to the absorption of toxicant metals into the body of fungus. Let’s turn our attention to mushrooms. Like other fungi, mushrooms can absorb large quantities of heavy metals. In fact, they may contain up to two and a half times the concentration of toxicant metals found in the soil they’re growing. So mushrooms, at least what we say about ground, we can potentially harvest them and then, once for all, safely desposits the pollutants contained within them. In fact, to clean up, especially the ground water system permanently, harvesting mushrooms is probably the best way to go. For some reason, this hasn’t happen as far as I know. But I can easily envision cultivating mushrooms for the sole purpose of detoxifying a large underground ecosystem.<img src="/upload/image/1516178179337.png" alt="" width="510" height="384" /><img src="/upload/image/1516178190415.png" alt="" width="517" height="383" /><img src="/upload/image/1516178204521.png" alt="" width="514" height="391" /><img src="/upload/image/1516178220784.png" alt="" width="513" height="386" /><img src="/upload/image/1516178237862.png" alt="" width="505" height="381" /><img src="/upload/image/1516178251056.png" alt="" width="514" height="389" />

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