Desert Plants托福聽力原文翻譯及問題答案

Desert Plants托福聽力原文翻譯及問題答案

一、Desert Plants托福聽力原文：

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托福聽力中文翻譯：

女教授：許多生物體已經(jīng)發(fā)展出在惡劣的環(huán)境條件下生存的能力，如酷熱或寒冷，或非常干燥的條件。。。。比如，《沙漠中的植物》你的教科書沒有太多關(guān)于沙漠植物的細(xì)節(jié)，但我認(rèn)為沙漠植物是適應(yīng)極端環(huán)境條件的絕佳例子。

因此，對于沙漠植物，基本上有三種不同的適應(yīng)策略。我要指出的是，這些策略并不是特定于任何特定物種的，許多不同的物種已經(jīng)發(fā)展出了每種適應(yīng)。

首先，有肉質(zhì)植物。

肉質(zhì)植物有很多種，但它們都能吸收和儲存大量水分。顯然，在沙漠中取水的機會非常少。一般來說，雨水少而短，因此雨水不會滲入土壤太深……任何植物在蒸發(fā)之前獲取水分的時間窗口都是有限的。

但是肉質(zhì)植物有一個擴展的淺根系，可以快速地從土壤頂部吸水，盡管土壤必須是飽和的，因為肉質(zhì)植物不善于從只有一點點潮濕的土壤中吸水。

多汁植物也非常適合在很少下雨的環(huán)境中保持水分。肉質(zhì)植物可以在葉子、莖或根中儲存水分。

為了防止水分在炎熱的沙漠陽光下蒸發(fā)，大多數(shù)肉質(zhì)植物都有一層蠟狀的外層，當(dāng)氣孔關(guān)閉時，它幾乎可以防水。

它們還通過最小化表面積來保存水分。植物在陽光下的面積越大，失去儲存的水分的可能性就越大，這意味著大多數(shù)多汁植物的葉子就越少。

現(xiàn)在除了肉質(zhì)植物外，還有耐旱植物。耐旱植物在某種程度上就像熊。你知道熊是怎么度過冬天的嗎？它們可以不吃東西而生存，因為它們的新陳代謝減慢。嗯，耐旱植物在資源短缺時也會進(jìn)入休眠狀態(tài)。一種耐旱的植物實際上可以干涸而不死亡。

我之前說過，大多數(shù)沙漠降雨是短暫的，但偶爾也會有大雨。耐旱植物在其中一場重要的降雨后復(fù)活，由于根系深厚，它們能夠吸收大量的降雨。實際上，耐旱植物的根系比生活在潮濕氣候中的許多植物的根系更為廣泛。與肉質(zhì)植物相比，耐旱植物甚至可以從相對干燥的土壤中吸收水分，因為它們的根很深。

第三種適應(yīng)性策略是完全避免干旱條件。是的，有這樣的植物——一年生植物。

一年生植物將在一個季節(jié)成熟并產(chǎn)生種子，成為下一代一年生植物。在沙漠條件下，一年生植物在秋季或春季生長，以避免夏季炎熱和冬季寒冷。當(dāng)然，這些植物可能面臨嚴(yán)重的問題，如果某個特定的秋天或春天非常干燥，它們將難以生長，并可能在產(chǎn)生種子之前死亡。

但他們有一種機制來防止一年的低降雨量將其抹去。并非一棵一年生植物產(chǎn)出的所有種子都會在第二年生長。有些種子在地里休眠了幾年。這是一種保護(hù)一年生植物免受惡劣生長條件和不利天氣影響的保險。

三、Desert Plants托福聽力問題：

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托福聽力答案：

A1:正確答案：B

A2:正確答案：AD

A3:正確答案：C

A4:正確答案：A

A5:正確答案：D

A6:正確答案：B

>> 雅思 托福 免費測試、量身規(guī)劃、讓英語學(xué)習(xí)不再困難<<