The Role of Ethylene托福红Delta听力原文翻译及问题答案

The Role of Ethylene托福红Delta听力原文翻译及问题答案，今天中国教育在线就来为大家分析这个问题。

一、The Role of Ethylene托福红Delta听力原文：

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托福红Delta听力中文翻译：

W：与植物生长和衰老相关的几个过程涉及激素的影响。今天，我将讨论两个衰老过程：果实的成熟和秋天树叶的凋落。这些过程涉及一种叫做乙烯的激素。什么是乙烯？它是一种化学物质，是植物作为激素产生的气体。乙烯在植物激素中是独一无二的，因为它是唯一一种气体激素。气态很重要，因为它使乙烯能够在工厂中流动。像所有其他激素一样，乙烯会引发植物的某些反应。乙烯与多种老化过程有关。衰老过程的一个例子是水果的成熟。水果的成熟涉及到结构和代谢的几个变化。其中一些变化是老化过程。其中一个变化是细胞壁变弱，使果实变软。另一个原因是叶绿素含量减少，导致水果失去绿色。乙烯会引发或加速这两种变化，也会导致一些成熟的水果从植物上掉落。在成熟过程中会发生连锁反应，因为乙烯会引发老化。然后老化的细胞释放更多的乙烯。因为乙烯是一种气体，成熟的信号从一个水果传播到另一个水果。你听过这样一句话：“一个坏苹果毁了一切。”嗯，这真的是真的！是的Randy？

M：所以，当我们买水果时，比如桃子仍然是绿色的，我们把它们放在塑料袋里，桃子成熟得更快，这是因为乙烯吗？我是说，我想我明白了。这种袋子可以捕获乙烯气体，从而加速成熟。

W：对。事实就是这样。乙烯在塑料袋内积聚，从而引发连锁反应。成熟的信号从一个桃子传播到另一个桃子，这会导致所有桃子更快成熟。

顺便说一下，乙烯的作用是以一种有趣的方式被发现的。一个世纪前，柑橘种植者习惯于在煤油炉加热的棚子里“固化”水果，使其成熟。种植者认为是炉子的热量使水果成熟。然而，他们后来发现，在开始使用更新、更清洁的炉子后，水果并没有成熟。植物学家发现，水果在煤油炉棚中成熟的原因是乙烯，而不是热量，因为事实证明，乙烯是煤油燃烧的副产品。如今，许多水果在装有乙烯气体管道的巨大储存容器中成熟。这是旧养护棚的新变种。但在其他情况下，储存设施必须减缓天然乙烯引起的成熟。例如，苹果储存在用二氧化碳冲洗的箱子里。使空气与二氧化碳循环可防止乙烯积聚，而二氧化碳会减缓任何乙烯未被冲走的情况下的反应。这就是苹果在运到超市之前可以储存几个月的方法。

乙烯在植物中起作用的另一个老化过程是秋天落叶。当一片叶子从树上掉落时，断裂点是叶子茎基部附近的一层。乙烯和生长素两种激素平衡的变化控制着叶片的脱落。衰老的叶子产生的生长素越来越少，生长素是一种刺激细胞生长的激素。生长素的下降使断裂层的细胞对乙烯更加敏感。随着乙烯的影响越来越强，细胞开始产生酶，削弱破坏层的细胞壁。最后，在风或雨的帮助下，树叶从这一层脱落，从树上落下。

三、The Role of Ethylene托福红Delta听力问题：

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托福红Delta听力答案：

A1:正确答案：A

A2:正确答案：D

A3:正确答案：AC

A4:正确答案：C

A5:正确答案：AABA

A6:正确答案：B

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