Desert Plants托福听力原文翻译及问题答案

Desert Plants托福听力原文翻译及问题答案

一、Desert Plants托福听力原文：

FEMALE PROFESSOR:Many organisms have developed the ability to survive in harsh environmental conditions—extreme heat or cold,or,very dry conditions....Like,plants in the desert—your textbook doesn’t have much about the specifics on desert plants,but I think that desert plants are great examples of specialized adaptations to extreme environmental conditions.

So with desert plants,there are basically three different adaptive strategies.And I should point out that these strategies are not specific to any particular species—many different species have developed each of the adaptations.

So,first off,there are succulent plants.

There are many different species of succulent plants,but they all can absorb and store a lot of water.Obviously,opportunities to get water in the desert are few and far between.Generally,rains are light and short,so the rain doesn’t seep too far down into the soil…and there's a limited window of time for any plant to get the water before it evaporates.

But succulent plants have a spread-out and shallow root system that can quickly pull in water from the top inch of soil,though the soil has to be saturated,since succulents aren't good at absorbing water from soil that’s only a little moist.

Succulent plants also are well suited to retaining water—important in an environment where rainy days are rare.Succulent plants can store water in their leaves,in their stems,or in their roots.

And to keep that moisture from evaporating in the hot desert sun,most succulent plants have a waxy outer layer that makes them almost waterproof when their stomates are closed.

They also preserve water by minimizing their surface area—the more of the plant that’s out in the sun,the more potential there is to lose stored-up water—and that means that most succulent plants have few,if any,leaves.

Now besides succulent plants,there are also drought-tolerant plants.Drought-tolerant plants are like bears in a way.You know how bears mostly sleep through the winter?They can survive without eating because their metabolism slows down.Well,drought-tolerant plants also go into a dormant state when resources—in their case,water—runs short.A drought-tolerant plant can actually dry out without dying.

I said before that most desert rains are light and brief,but occasionally there's a heavy one.Drought-tolerant plants revive after one of these significant rainfalls—and they're able to absorb a good bit of the rainfall due to their deep roots.Actually the root system for drought-tolerant plants is more extensive than the root systems of many plants that live in wetter climates.Drought-tolerant plants can even absorb water from relatively dry soil because of their deep roots,in contrast to succulent plants.

The third adaptive strategy is to avoid the drought conditions altogether.Yes,there are plants that do this—annual plants.

An annual plant will mature and produce seeds in a single season that will become the next generation of annual plants.In desert conditions,annual plants grow in the fall or spring to avoid the heat of summer and the cold of winter.Of course,these plants could face a serious problem if a particular fall or spring happened to be very dry—they would have difficulty growing and could die before producing seeds.

But they have a mechanism to prevent one year of low rainfall from wiping them out.Not all seeds an annual plant puts out will grow the following year.Some seeds remain dormant in the ground for several years.It's a type of insurance that protects the annual plants from a season of poor growing conditions,of unfavorable weather.

二、Desert Plants托福听力中文翻译：

女教授：许多生物体已经发展出在恶劣的环境条件下生存的能力，如酷热或寒冷，或非常干燥的条件。。。。比如，《沙漠中的植物》你的教科书没有太多关于沙漠植物的细节，但我认为沙漠植物是适应极端环境条件的绝佳例子。

因此，对于沙漠植物，基本上有三种不同的适应策略。我要指出的是，这些策略并不是特定于任何特定物种的，许多不同的物种已经发展出了每种适应。

首先，有肉质植物。

肉质植物有很多种，但它们都能吸收和储存大量水分。显然，在沙漠中取水的机会非常少。一般来说，雨水少而短，因此雨水不会渗入土壤太深……任何植物在蒸发之前获取水分的时间窗口都是有限的。

但是肉质植物有一个扩展的浅根系，可以快速地从土壤顶部吸水，尽管土壤必须是饱和的，因为肉质植物不善于从只有一点点潮湿的土壤中吸水。

多汁植物也非常适合在很少下雨的环境中保持水分。肉质植物可以在叶子、茎或根中储存水分。

为了防止水分在炎热的沙漠阳光下蒸发，大多数肉质植物都有一层蜡状的外层，当气孔关闭时，它几乎可以防水。

它们还通过最小化表面积来保存水分。植物在阳光下的面积越大，失去储存的水分的可能性就越大，这意味着大多数多汁植物的叶子就越少。

现在除了肉质植物外，还有耐旱植物。耐旱植物在某种程度上就像熊。你知道熊是怎么度过冬天的吗？它们可以不吃东西而生存，因为它们的新陈代谢减慢。嗯，耐旱植物在资源短缺时也会进入休眠状态。一种耐旱的植物实际上可以干涸而不死亡。

我之前说过，大多数沙漠降雨是短暂的，但偶尔也会有大雨。耐旱植物在其中一场重要的降雨后复活，由于根系深厚，它们能够吸收大量的降雨。实际上，耐旱植物的根系比生活在潮湿气候中的许多植物的根系更为广泛。与肉质植物相比，耐旱植物甚至可以从相对干燥的土壤中吸收水分，因为它们的根很深。

第三种适应性策略是完全避免干旱条件。是的，有这样的植物——一年生植物。

一年生植物将在一个季节成熟并产生种子，成为下一代一年生植物。在沙漠条件下，一年生植物在秋季或春季生长，以避免夏季炎热和冬季寒冷。当然，这些植物可能面临严重的问题，如果某个特定的秋天或春天非常干燥，它们将难以生长，并可能在产生种子之前死亡。

但他们有一种机制来防止一年的低降雨量将其抹去。并非一棵一年生植物产出的所有种子都会在第二年生长。有些种子在地里休眠了几年。这是一种保护一年生植物免受恶劣生长条件和不利天气影响的保险。

三、Desert Plants托福听力问题：

Q1:1.What is the lecture mainly about?

A.The growth rates of plants in different geographical regions

B.Different ways that plants have adapted to desert environments

C.The different mechanisms that plant roots use to absorb water

D.Different kinds of succulent plants

Q2:2.What are two features of succulent plants that help them survive in deserts?[Click on 2 answers.]

A.Succulent plants store water in their leaves and stems.

B.Succulent plants become dormant until the next rainfall.

C.Succulent plants have short stems.

D.Succulent plants have few leaves.

Q3:3.Why does the professor mention bears?

A.To remind students of information from a previous lecture

B.To point out a feature common to all desert plants

C.To reinforce a point about drought-tolerant plants

D.To help students understand the concept of adaptation

Q4:4.What is one ability that drought-tolerant plants have that succulent plants do not have?

A.The ability to absorb water from dry soil

B.The ability to absorb water through their leaves

C.The ability to prevent moisture from being lost through their leaves

D.The ability to shed leaves

Q5:5.Why can annual plants grow in a desert even after a year of no rainfall?

A.Annual plants have an extensive root system that can absorb water from far away.

B.Annual plants produce seeds all year long.

C.Seeds of annual plants can store water for a long time.

D.Seeds of annual plants can survive in the ground for a long time without water.

Q66.Listen again to part of the lecture.Then,answer the question.(PROFESSOR)The third adaptive strategy is to avoid the drought conditions altogether.Yes,there are plants that do this.Why does the professor say this:(PROFESSOR)Yes,there are plants that do this.

A.To correct a previous statement

B.To acknowledge a potentially surprising fact

C.To anticipate the types of questions that students might have about the topic

D.To make sure that students are paying attention:

四、Desert Plants托福听力答案：

A1:正确答案：B

A2:正确答案：AD

A3:正确答案：C

A4:正确答案：A

A5:正确答案：D

A6:正确答案：B

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