Fungi托福听力原文翻译及问题答案

Fungi托福听力原文翻译及问题答案

一、Fungi托福听力原文：

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

FEMALE PROFESSOR:When you try to imagine a fungus,you probably picture a mushroom popping up out of the ground…and think that’s it.But a fungus like that…most of it actually lives underground.

And fungi in general are often an important active component of the soil.A fungus secretes enzymes into the soil,enzymes that break down…decompose organic material 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 may enable fungi to help clean up environmental pollution in the soil…And that's 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're not.Believe it or not,the only other place chitin is found in abundance is in the exoskeletons of insects,crabs,and such!So,in this sense,fungi are more associated with insects than with any plant.Strange,huh?

And the chitin in the cell walls of a filamentous fungus…A filament,of course,is a long,threadlike structure—cells joined end to end.Filamentous fungi grow in soil and in decaying vegetation,and,as their name implies,they exist as filaments.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.Their vast surface area allows them to break down and take in huge amounts of nutrients.But beyond that,the filiments also pull out of the soil a great deal of the pollution that might be in there,especially heavy metals.

And here's 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.

Now don't confuse this with absorption,where a substance is 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 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.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 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 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.We can put these filters into waste pipes from industrial processes and use the filters to trap heavy metals,like mercury and zinc.Later,we can chemically extract the heavy metals and reuse the filter over and over.

Now,going back to the absorption of toxic metals into the body of the 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 toxic metals found in the soil they grow in.So mushrooms,at least what we see above ground…we can potentially harvest them and then,once and for all,safely dispose of the pollutants contained within them.

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

二、Fungi托福听力中文翻译：

旁白：在环境科学课上听讲座的一部分。

女教授：当你试着想象一种真菌时，你可能会想象一个蘑菇从地里冒出来……然后想就是这样。但像这样的真菌……大部分实际上生活在地下。

真菌通常是土壤的重要活性成分。真菌向土壤中分泌酶，分解酶……分解土壤中的有机物质……因此真菌可以吸收这些物质并获得营养。

但对我来说，这个过程最有趣的是它如何使真菌帮助清理土壤中的环境污染……这部分要归功于它们细胞壁中一种叫做甲壳素的物质。

现在很多人认为真菌与植物有关，但事实并非如此。信不信由你，甲壳素在昆虫、螃蟹等动物的外骨骼中也大量存在！因此，从这个意义上说，真菌与昆虫的关系比与任何植物的关系都要密切。奇怪吧？

丝状真菌细胞壁中的几丁质……当然，丝状结构是一种长的线状结构，细胞端对端连接在一起。丝状真菌生长在土壤和腐烂的植被中，顾名思义，它们以丝状存在。而且，尽管被视为微生物，但单个真菌的细丝可以扇出，占据许多平方米甚至数平方公里的森林地面。它们巨大的表面积使它们能够分解并吸收大量的营养物质。但除此之外，这些软泥还会从土壤中带走大量可能存在的污染，尤其是重金属。

这就是几丁质的来源。像真菌细胞壁中的其他一些物质一样，甲壳素与环境中的重金属形成强大的化学键……这一过程我们称之为吸附。

现在不要把这与吸收混淆，物质被吸收到细胞中，进入细胞内部。我的意思是，这也发生在这里，但吸附意味着结合到细胞的外表面。丝状真菌可以吸附有毒重金属……将它们结合到其巨大丝状网络的表面，从而为大型土壤生态系统解毒。重金属仍然存在，但大量的这些金属可能会与几丁质结合……与土壤中丝状真菌的细胞壁结合……从而在长达30年的时间内保持化学活性，甚至更长时间，而不是渗入水系统并污染地下水。

事实上，我们实际上可以使用丝状真菌的细胞壁作为过滤器，即使在真菌死亡之后。

例如，制药工业在实验室大量种植丝状真菌。例如，为了生产抗生素青霉素，制药公司种植真菌青霉。提取青霉素后，这些死青霉丝……我们可以利用其细胞壁中的几丁质制造工业过滤器来吸附重金属。我们可以将这些过滤器放入工业过程中的废水管道中，并使用这些过滤器来捕集汞和锌等重金属。之后，我们可以用化学方法提取重金属并反复使用过滤器。

现在，回到真菌体内对有毒金属的吸收，让我们把注意力转向蘑菇。

与其他真菌一样，蘑菇可以吸收大量重金属。事实上，它们所含的有毒金属浓度可能是它们生长的土壤中有毒金属浓度的两倍半。所以蘑菇，至少是我们在地面上看到的……我们可以潜在地收获它们，然后一劳永逸地安全处理其中所含的污染物。

事实上，为了永久性地清理……尤其是地下水系统……收获蘑菇可能是最好的方式。据我所知，出于某种原因，这种情况尚未发生。但我可以很容易地想象，培养蘑菇的唯一目的是为大型地下生态系统排毒。

三、Fungi托福听力问题：

Q1:1.What is the lecture mainly about?

A.Why fungi cannot grow well in polluted ecosystems

B.Why fungi pose a danger to the underground water system

C.How to prevent heavy metals from getting into the soil

D.How fungi can clean up pollution that is in the soil

Q2:2.What does the professor say about the way fungi get their food?

A.They use certain metal compounds in the soil as nutrients.

B.The enzymes that they produce allow them to absorb organic nutrients from the soil.

C.They separate nutrients from heavy metals and then return the metals to the soil.

D.Heavy metals interfere with their way of getting nutrients from the soil.

Q3:3.What two points does the professor make about chitin?[Click on 2 answers.]

A.Chitin binds strongly to certain heavy metals.

B.Insects need chitin in order to digest the fungi they eat.

C.Chitin can be added to soil to create a good habitat for fungi.

D.The cell walls of fungi,like the exoskeletons of insects,contain chitin.

Q4:4.What do adsorption and absorption in fungi have in common?

A.They both can help the production of new filaments.

B.They both can increase the production of chitin.

C.They both can help keep pollutants out of groundwater.

D.They both result in the strengthening of cell walls.

Q5:5.Why does the professor mention the antibiotic penicillin?

A.To suggest that more fungi should be investigated as potential sources of medications

B.To point out that certain heavy metals are needed for the production of penicillin

C.To criticize the pharmaceutical industry for contributing to environmental pollution

D.To show how a waste product from one process can be useful in another process

Q6:6.Replay:Why does the professor say this: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？

A.She does not have time to fully explain the reason.

B.She is hopeful that students will be able to figure out the reason.

C.She wonders why mushrooms are not already used for cleaning up pollution.

D.She realizes that the research she has been discussing is still in its early stages.

四、Fungi托福听力答案：

A1:正确答案：D

A2:正确答案：B

A3:正确答案：AD

A4:正确答案：C

A5:正确答案：D

A6:正确答案：C

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