托福备考托福阅读34套TPO样题+解析+译文26—2 Survival of Plants and Animals in Desert Conditions

托福考试 复习

TPO 26—2 Survival of Plants and Animals in Desert Conditions 原文：

【1】The harsh conditions in deserts are intolerable for most plants and animals. Despite these conditions, however, many varieties of plants and animals have adapted to deserts in a number of ways. Most plant tissues die if their water content falls too low: the nutrients that feed plants are transmitted by water; water is a raw material in the vital process of photosynthesis; and water regulates the temperature of a plant by its ability to absorb heat and because water vapor lost to the atmosphere through the leaves helps to lower plant temperatures. Water controls the volume of plant matter produced. The distribution of plants within different areas of desert is also controlled by water. Some areas, because of their soil texture, topographical position, or distance from rivers or groundwater, have virtually no water available to plants, whereas others do.

【2】The nature of plant life in deserts is also highly dependent on the fact that they have to adapt to the prevailing aridity. There are two general classes of vegetation: long-lived perennials, which may be succulent (water-storing) and are often dwarfed and woody, and annuals or ephemerals, which have a short life cycle and may form a fairly dense stand immediately after rain.

【3】The ephemeral plants evade drought. Given a year of favorable precipitation, such plants will develop vigorously and produce large numbers of flowers and fruit. This replenishes the seed content of the desert soil. The seeds then lie dormant until the next wet year, when the desert blooms again.

【4】The perennial vegetation adjusts to the aridity by means of various avoidance mechanisms. Most desert plants are probably best classified as xerophytes. They possess drought-resisting adaptations: loss of water through the leaves is reduced by means of dense hairs covering waxy leaf surfaces, by the closure of pores during the hottest times to reduce water loss, and by the rolling up or shedding of leaves at the beginning of the dry season. Some xerophytes, the succulents (including cacti), store water in their structures. Another way of countering drought is to have a limited amount of mass above ground and to have extensive root networks below ground. It is not unusual for the roots of some desert perennials to extend downward more than ten meters. Some plants are woody in type —an adaptation designed to prevent collapse of the plant tissue when water stress produces wilting. Another class of desert plant is the phreatophyte. These have adapted to the environment by the development of long taproots that penetrate downward until they approach the assured water supply provided by groundwater. Among these plants are the date palm, tamarisk, and mesquite. They commonly grow near stream channels, springs, or on the margins of lakes.

【5】Animals also have to adapt to desert conditions, and they may do it through two forms of behavioral adaptation: they either escape or retreat. Escape involves such actions as aestivation, a condition of prolonged dormancy, or torpor, during which animals reduce their metabolic rate and body temperature during the hot season or during very dry spells.

【6】Seasonal migration is another form of escape, especially for large mammals or

birds. The term retreat is applied to the short-term escape behavior of desert animals, and it usually assumes the pattern of a daily rhythm. Birds shelter in nests, rock overhangs, trees, and dense shrubs to avoid the hottest hours of the day, while mammals like the kangaroo rat burrow underground.

【7】Some animals have behavioral, physiological, and morphological (structural) adaptations that enable them to withstand extreme conditions. For example, the ostrich has plumage that is so constructed that the feathers are long but not too dense. When conditions are hot, the ostrich erects them on its back, thus increasing the thickness of the barrier between solar radiation and the skin. The sparse distribution of the feathers, however, also allows considerable lateral air movement over the skin surface, thereby permitting further heat loss by convection. Furthermore, the birds orient themselves carefully with regard to the Sun and gently flap their wings to increase convection cooling. 题目：

托福阅读试题

1.According to paragraph 1, water provides all of the following essential functions for plants EXCEPT

A.improving plants’ ability to absorb sunlight.

B.preventing plants from becoming overheated. C.transporting nutrients.

D.serving as a raw material for photosynthesis.

2.Paragraph 3 suggests that during a dry year ephemerals A.produce even more seeds than in a wet year. B.do not sprout from their seeds. C.bloom much later than in a wet year. D.are more plentiful than perennials.

3.How is paragraph 2 related to paragraph 3?

A.Paragraph 2 provides a general description of desert plants, and paragraph 3 provides a scientific explanation for these observations.

B.Paragraph 2 divides desert plants into two categories, and paragraph 3 provides further information about one of these categories.

C.Paragraph 2 proposes one way of dividing desert plants into categories, and paragraph 3 explains one problem with this method of classification.

D.Paragraph 2 discusses two categories of desert plants, and paragraph 3 introduces a third category of plants.

4.In saying that ephemerals will develop “vigorously\" when there is favorableprecipitation, the author means that their development will be A.sudden. B.early. C.gradual.

D.strong and healthy.

5.The word “countering”in the passage is closest in meaning to A.eliminating. B.making use of. C.acting against. D.experiencing.

6.According to paragraph 4, some desert plants with root systems that are extraordinarily well developed have A.relatively little growth aboveground. B.very leafy aboveground structures. C.non woody plant tissue resistant to wilting. D.water stored within their roots.

7.The word “assured”(paragraph 4)in the passage is closest in meaning to A.pure. B.diminished. C.guaranteed. D.deep.

8.What do “the date palm, tamarisk, and mesquite\"(paragraph 4) have in common? A.They are always found together.

B.They depend on surface water provided by streams, springs, and lakes. C.They are phreatophytes.

D.Their roots are capable of breaking through hard soils

9.Which of the sentences below best expresses the essential information inthe highlighted sentence in the passage(paragraph 5)? Incorrect choices change the meaning in important ways or leave out essential information.

A.One way animals escape is by entering a state of extended dormancy, known as aestivation, during the hottest and driest times of year.

B.Animals can escape without using direct action, or aestivation, simply by reducing their metabolic rate and body temperature.

C.The actions that an animal uses to escape are known as aestivation, which sometimes involves a reduction in metabolic rate or body temperature.

D.When the weather is especially hot and dry, an animal may suffer from a condition known as aestivation, at which point the animal needs to escape.

10.It can be inferred from paragraph 6 that all of the places desertanimals retreat to

A.provide shade from the sun. B.sometimes become crowded.

C.are places where supplies of food are plentiful. D.leave the animals vulnerable to predators.

11.According to paragraph 7, what special adaptation helps the ostrich copewith hot desert conditions?

A.Each of its feathers is very short and dense.

B.Its wings produce only lateral air movement when flapping. C.Its feathers are very thickly set on both its back and its wings.

D.It can make its feathers stand up on its back.

12. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Where would the sentence best fit? The increase in reward still did not attract young people to this hard life, and convicted criminals and slaves were pressed into services

The harsh conditions in deserts are in tolerable for most plants and animals. Despite these conditions, however, many varieties of plants and animals have adapted to deserts in a number of ways. Most plant tissues die if their water content falls too low: the nutrients that feed plants are transmitted by water; water is a raw material in the vital process of photosynthesis; and water regulates the temperature of a plant by its ability to absorb heat and because water vapor lost to the atmosphere through the leaves helps to lower plant temperatures. ■【A】Water controls the volume of plant matter produced. ■【B】The distribution of plants within different areas of desert is also controlled by water. ■【C】Some areas, because of their soil texture,to pographical position, or distance from rivers or groundwater, have virtually no water available to plants, whereas others do.■【D】

13.Directions: Select from the seven phrases below the two phrases that correctly characterize special adaptations found primarily in desert annuals and the three phrases that correctly characterize special adaptations found primarily in desert perennials. Select each phrase you select in the appropriate column of the table. This question is worth 3 points. A.Woody structures.

B.Explosive growth in wet years. C.Long, thin, shallow roots. D.Storage of water in plant tissue.

E.Minimization of the amount of water used for photosynthesis. F.Short life cycle.

G.Leaves designed to minimize water loss. 1 ）

Adaptations of Annuals A B C D E F G 2 ）

Adaptations of Perennials A B C D E F G 答案：

1.A选项的sunlight原文没有提到，所以错误，选；B项不容易找，可以找完C和D之后依靠并列在第三句的冒号之后找到，原文讲的是降低温度，也就是防止overheated，所以B正确，不选；C和D都在第三句的冒号之后，都正确，不选。

2.以dry year和ephemeral做关键词定位至首句，但只看这句话没有答案，于是看最后一句，讲植物种子直到下个wet year之前都dormant，也就是dry year的时候它们休眠，所以正确答案是B。注意C有迷惑性，虽然原文提到了wet year，但没有讲干湿年份进行比较，所以C错；A犯了跟C相同的错误；D错在原文没有把ephemeral跟perennial进行比较。

3.问两段关系，看开头。第二段开头说植物需要适应沙漠的干旱环境，第二句说有两类；第三段开头讲其中一类，因此应该是第二段总述，第三段分述，所以正确答案是B。A错在第三段没有scientific explanation；C错在第三段不是讲分类的问题；D错在第三段讲的是第二段两个分类中的一个，而不是第三类。

4.vigorously活泼地，精力旺盛地，所以正确答案是strong。代入，原文说在降水多的时候，植物怎么生长，这个凭常识也知道降水多的时候植物长的好吧，不认识precipitation的同学可以看后面的并列，叫做产生大量的花和果实，还是可以推出长得好。

5.countering反，抵御，抵抗，所以正确答案是C。counter本身就表示反对，想想encounter，counteract，counterbalance，还有著名游戏CS。不知道的同学代入，另外一种怎么样干旱的方法是植物地上部分小地下部分大，地下部分大吸收水分多，是应对干旱的方法。A消除干旱和B利用干旱明显不通；D经历干旱也不要什么特殊的方法，不对。

6.以root systems that are extraordinarily well developed做关键词定位至第五句，也就是上个词汇题的那句，说另外一种抗击干旱的方法是植物地上部分小地下部分大，所以正确答案是A。B刚好说反；C的nonwoody和D的water都不在定位句中。

7.assured确定的，经过证实的，所以正确答案是guaranteed。词根是sure，所以肯定与确定有关，pure跟deep就完全不对；不认识diminished的同学至少看到词中间有个mini，跟小或者少有关，所以也不对。

8.以date palm, tamarisk and mesqute做关键词定位至倒数第二句，这句尽管没法做答案，但these告诉我们和前句有关，往前看又发现一个these，于是继续往前，终于读到倒数第四句说另一种沙漠植物是ph，所以正确答案是C，其他都没说。

9.提取主干，去掉during which从句得到escape的方法包括aestivation。很容易排除B和D，因为B说不用aestivation，D说suffer；C最明显的错误是减少metabolic rate or

body temperature，而原文讲的是metabolic rate and body temperature，所以正确答案是A，而且C只讲了escape包含叫aestivation的方式。C选项错误的另一个原因是没有将involve这层包含关系讲出来。

10.以desert animals retreat做关键词定位至首句，说包含两种方法，一是escape，二是retreat，但接下来的整段都在讲escape，没有retreat的事儿，不知道是不是我的理解有问题，这道题真正的答案应该在下一段，下一段第二句开始讲retreat，尾句讲鸟retreat为了躲避炎热，哺乳动物躲到洞里，也就是说retreat是为了避暑，正确答案是A。如果没有看到下一段的同学，这段最后一句讲escape发生在炎热或者干燥的时期，同样可以推出躲避阳光，这是个infer题。

11.以ostrich做关键词定位至第二句和第三句，第三句说当炎热的时候，ostrich会竖起它们背上的羽毛，所以正确答案是D。B没提到feather，错；A说feather短，错；C的both blabla原文没说，错。

12.据flyjoy童鞋所说，待插入句是“For this reason, the total amount of plant material in a desert is often 100 times less than the amount of plant material in an equivalent area of temperate forest.”如果是这句，那么以不同的area做过渡点，可能的正确答案是B/C/D，但由于for this reason，说明待插入句与前句之间是因果关系，能够构成因果关系的只有D选项。感谢flyjoy童鞋提供正确版本。

13.Annual跟Perennial主要在第二至第四段讲到。Woody选项在第二段第二句刚讲到分类的时候，属于perennial。Explosive选项在第二段最后以及整个第三段都有讲到，尽管不是原词，但说到一旦降水多就立刻生长的很好，也就是explosive了，所以属于annual。Long选项错，因为原文说extensive root network是应付干旱的方法，没讲到shallow root。Storage选项同样在第二段第二句刚讲到分类的时候就说了，属于perennial。

Minimization选项原文完全没讲到，不是任何一个category的选项。Short选项同样在第二段第二句刚讲到分类的时候就说了，属于annual。Leaves选项在第四段第二句，属于perennial。