The Role of Ethylene托福紅Delta聽力原文翻譯及問題答案

The Role of Ethylene托福紅Delta聽力原文翻譯及問題答案，今天中國教育在線就來為大家分析這個問題。

一、The Role of Ethylene托福紅Delta聽力原文：

W:Several of the processes related to growth and aging in plants involve the effects of hormones.Today I’ll talk about two aging processes—the ripening of fruit and the falling of leaves in autumn.These processes involve a hormone called ethylene.What is ethylene?It’s a chemical,a gas produced by plants as a hormone.Ethylene is unique among plant hormones because it’s the only hormone that’s a gas.The gaseous state is important because it enables ethylene to move through the plant.Like all other hormones,ethylene triggers certain responses in the plant.Ethylene is associated with a variety of aging processes.One example of the aging process is the ripening of fruit.The ripening of fruit involves several changes in structure and metabolism.Some of these changes are aging processes.One change is the weakening of cell walls,which softens the fruit.Another is the decrease in chlorophyll content,which causes the fruit to lose its greenness.Ethylene initiates or hastens both of these changes and also causes some ripened fruit to drop from the plant.A chain reaction occurs during ripening,as ethylene triggers aging.The aging cells then release more ethylene.Because ethylene is a gas,the signal to ripen spreads from fruit to fruit.You’ve heard the expression“One bad apple spoils the whole lot.”Well,it really is true!Yes,Randy?

M:So,when we buy fruit,like peaches that are still kind of green,and we store them in a plastic bag,and the peaches ripen faster—is this because of ethylene?I mean,I think I get it.The bag traps the ethylene gas,and this speeds up the ripening.

W:Right.That’s exactly what happens.Ethylene accumulates inside the plastic bag,and this starts a chain reaction.The signal to ripen spreads from one peach to another,and this causes all of the peaches to ripen faster.

By the way,the role of ethylene was discovered in sort of an interesting way.A century ago,citrus growers used to ripen fruit by“curing”it in sheds that were heated by kerosene stoves.The growers thought it was the heat from the stoves that ripened the fruit.However,they later discovered that the fruit didn’t ripen after they started using newer,cleaner-burning stoves.Botanists figured out that the reason the fruit ripened in the sheds with kerosene stoves was because of ethylene—not heat—because,as it turns out,ethylene is a by-product of kerosene combustion.Nowadays,a lot of fruit is ripened in huge storage containers that have ethylene gas piped in.It’s a new variation on the old curing shed.But in other cases,storage facilities have to slow down the ripening caused by natural ethylene.For example,apples are stored in bins that are flushed with carbon dioxide.Circulating the air with carbon dioxide prevents ethylene from accumulating,and carbon dioxide slows down the action of whatever ethylene isn’t flushed away.This is how apples can be stored for several months before they’re shipped to supermarkets.

Another aging process in plants where ethylene plays a role is the falling of leaves in autumn.When a leaf falls from a tree,the breaking point is a layer near the base of the leaf’s stalk.A change in the balance of two hormones—ethylene and auxin—controls the falling of leaves.An aging leaf produces less and less auxin,a hormone that stimulates cell growth.The drop in auxin makes the cells of the breaking layer more sensitive to ethylene.As the influence of ethylene becomes stronger,the cells start producing enzymes that weaken the cell walls of the breaking layer.Finally,with the help of wind or rain,the leaf breaks away at that layer and falls from the tree.

二、The Role of Ethylene托福紅Delta聽力中文翻譯：

W：與植物生長和衰老相關的幾個過程涉及激素的影響。今天，我將討論兩個衰老過程：果實的成熟和秋天樹葉的凋落。這些過程涉及一種叫做乙烯的激素。什么是乙烯？它是一種化學物質(zhì)，是植物作為激素產(chǎn)生的氣體。乙烯在植物激素中是獨一無二的，因為它是唯一一種氣體激素。氣態(tài)很重要，因為它使乙烯能夠在工廠中流動。像所有其他激素一樣，乙烯會引發(fā)植物的某些反應。乙烯與多種老化過程有關。衰老過程的一個例子是水果的成熟。水果的成熟涉及到結構和代謝的幾個變化。其中一些變化是老化過程。其中一個變化是細胞壁變?nèi)?，使果實變軟。另一個原因是葉綠素含量減少，導致水果失去綠色。乙烯會引發(fā)或加速這兩種變化，也會導致一些成熟的水果從植物上掉落。在成熟過程中會發(fā)生連鎖反應，因為乙烯會引發(fā)老化。然后老化的細胞釋放更多的乙烯。因為乙烯是一種氣體，成熟的信號從一個水果傳播到另一個水果。你聽過這樣一句話：“一個壞蘋果毀了一切?！编牛@真的是真的！是的Randy？

M：所以，當我們買水果時，比如桃子仍然是綠色的，我們把它們放在塑料袋里，桃子成熟得更快，這是因為乙烯嗎？我是說，我想我明白了。這種袋子可以捕獲乙烯氣體，從而加速成熟。

W：對。事實就是這樣。乙烯在塑料袋內(nèi)積聚，從而引發(fā)連鎖反應。成熟的信號從一個桃子傳播到另一個桃子，這會導致所有桃子更快成熟。

順便說一下，乙烯的作用是以一種有趣的方式被發(fā)現(xiàn)的。一個世紀前，柑橘種植者習慣于在煤油爐加熱的棚子里“固化”水果，使其成熟。種植者認為是爐子的熱量使水果成熟。然而，他們后來發(fā)現(xiàn)，在開始使用更新、更清潔的爐子后，水果并沒有成熟。植物學家發(fā)現(xiàn)，水果在煤油爐棚中成熟的原因是乙烯，而不是熱量，因為事實證明，乙烯是煤油燃燒的副產(chǎn)品。如今，許多水果在裝有乙烯氣體管道的巨大儲存容器中成熟。這是舊養(yǎng)護棚的新變種。但在其他情況下，儲存設施必須減緩天然乙烯引起的成熟。例如，蘋果儲存在用二氧化碳沖洗的箱子里。使空氣與二氧化碳循環(huán)可防止乙烯積聚，而二氧化碳會減緩任何乙烯未被沖走的情況下的反應。這就是蘋果在運到超市之前可以儲存幾個月的方法。

乙烯在植物中起作用的另一個老化過程是秋天落葉。當一片葉子從樹上掉落時，斷裂點是葉子莖基部附近的一層。乙烯和生長素兩種激素平衡的變化控制著葉片的脫落。衰老的葉子產(chǎn)生的生長素越來越少，生長素是一種刺激細胞生長的激素。生長素的下降使斷裂層的細胞對乙烯更加敏感。隨著乙烯的影響越來越強，細胞開始產(chǎn)生酶，削弱破壞層的細胞壁。最后，在風或雨的幫助下，樹葉從這一層脫落，從樹上落下。

三、The Role of Ethylene托福紅Delta聽力問題：

Q1:What is the lecture mainly about?

A.The role of ethylene in plant aging processes

B.The discovery of ethylene by fruit growers

C.Differences between ethylene and other hormones

D.How plant hormones influence growth

Q2:According to the professor,how is ethylene unique?

A.Ethylene is the only hormone that plants produce.

B.Ethylene is produced only in flowering plants.

C.Ethylene both stimulates and restricts plant growth.

D.Ethylene is the only plant hormone that is a gas.

Q3:According to the lecture,what are two effects of ethylene?

Click on two answers.

A.Fruit becomes softer as it ripens.

B.Plants develop complex root systems.

C.Trees shed their leaves in the fall.

D.Flower buds open in the spring.

Q4:Why does the professor say this:

A.To explain why she doesn’t like apples

B.To describe a common disease of fruit

C.To summarize the chain reaction of ripening

D.To caution against eating unwashed fruit

Q5:Based on the information in the lecture,indicate whether each process below is related to the hormone ethylene.

For each sentence,click in the correct box

Q6:What does the professor imply about the falling of leaves?

A.Leaves fall from old trees,but not from trees that are still young.

B.Both hormones and environmental factors cause leaves to fall.

C.The falling of leaves increases the tree’s risk of getting a disease.

D.Spraying ethylene into an orchard will prevent leaves from falling.

四、The Role of Ethylene托福紅Delta聽力答案：

A1:正確答案：A

A2:正確答案：D

A3:正確答案：AC

A4:正確答案：C

A5:正確答案：AABA

A6:正確答案：B

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