《托福TPO34阅读Passage3原文文本+题目+答案解析.pdf》由会员分享，可在线阅读，更多相关《托福TPO34阅读Passage3原文文本+题目+答案解析.pdf（11页珍藏版）》请在三一文库上搜索。
1、 为了帮助大家高效备考托福， 为大家带来托福 TPO34 阅读 Passage3 原文文本+题目+答案 解析，希望对大家备考有所帮助。 Protection of Plants by Insects 昆虫对植物的保护 Many plantsone or more species of at least 68 different familiescan secrete nectar even when they have no blossoms,because they bear extra floral nectaries(structures that produce nectar)on s
2、tems,leaves,leaf stems,or other structures.These plants usually occur where ants are abundant,most in the tropics but some in temperate areas.Among those of northeastern North America are various plums,cherries,roses,hawthorns,poplars,and oaks.Like floral nectar,extrafloral nectar consists mainly of
3、 water with a high content of dissolved sugars and,in some plants,small amounts of amino acids.The extrafloral nectaries of some plants are known to attract ants and other insects,but the evolutionary history of most plants with these nectaries is unknown.Nevertheless,most ecologists believe that al
4、l extrafloral nectaries attract insects that will defend the plant. 即使不开花，很多植物也能分泌花蜜(在至少 68 个不同的植物科里就有一种或多种分泌 花蜜的植物)。这是因为它们在茎，叶子，叶茎或其他结构上有花外蜜腺(保护花蜜的结构)。 这些植物通常生长在大量蚁群存在的地方，因此大多数生长在热带地方，但也有一些生长在 温带地区。在北美东北部地区就有这类植物，包括各种各样的李子，樱桃，蔷薇，山楂树， 白杨树和橡树。像花蜜一样，花外花蜜主要包括水，高浓度的溶解糖，在某些植物里，还有 少量的氨基酸。人们已经知道某些植物的花外蜜腺是为
5、了吸引蚂蚁和昆虫，但是目前大部分 带有花外蜜腺的植物的进化史人们还不得而知。尽管如此，大多数生态学家相信所有的花外 蜜腺都是为了吸引昆虫以便防御自身。 Ants are probably the most frequent and certainly the most persistent defenders of plants.Since the highly active worker ants require a great deal of energy,plants exploit this need by providing extrafloral nectar that suppl
6、ies ants with abundant energy.To return this favor,ants guard the nectaries,driving away or killing intruding insects that might compete with ants for nectar.Many of these intruders are herbivorous and would eat the leaves of the plants. 蚂蚁或许是植物的最常见也无疑是最执著的保护者了。因为高度活跃的工蚁需要很多能 量， 而植物正好可以利用这一需求， 为蚂蚁提供
7、花外蜜以满足它们的能量需求。 为了回报植物， 蚂蚁会保卫蜜腺，赶走或杀死入侵的昆虫，因为它们会和蚂蚁争夺蜜腺。很多入侵者是食草 动物，会吃掉植物的叶子。 Biologists once thought that secretion of extrafloral nectar has some purely internal physiological function,and that ants provide no benefit whatsoever to the plants that secrete it.This view and the opposing“protectionist
8、”hypothesis that ants defend plants had been disputed for over a hundred years when,in 1910,a skeptical William Morton Wheeler commented on the controversy.He called for proof of the protectionist view:that visitations of the ants confer protection on the plants and that in the absence of the insect
9、s a much greater number would perish or fail to produce flowers or seeds than when the insects are present.That we now have an abundance of the proof that was called for was established when Barbara Bentley reviewed the relevant evidence in 1977,and since then many more observations and experiments
10、have provided still further proof that ants benefit plants. 生物学家曾经认为分泌花外蜜只产生内部生理功能，蚂蚁对分泌花蜜的植物没有任何益 处。人们就该观点及其反方观点争执了很多年。反方观点坚持“保护主义者”假说，认为蚂 蚁能够保护植物。1910 年，怀疑论者威廉莫尔顿惠勒对这一争议做出了评论。他要求为“保 护主义者”观点提供证据 ： 蚂蚁能为植物提供保护;如果没有昆虫，更多植物将会消失，或者 不能开花或结种。 我们现在已经有充分证据表明昆虫的确有益于植物， 因为在 1977 年巴巴拉 宾利就已经研究了相关证据，并且自那以后，更多的观察
11、和实验也提供了更多的证据。 One example shows how ants attracted to extrafloral nectaries protect morning glories against attacking insects.The principal insect enemies of the North American morning glory feed mainly on its flowers or fruits rather than its leaves.Grasshoppers feeding on flowers indirectly block
12、pollination and the production of seeds by destroying the corolla or the stigma,which receives the pollen grains and on which the pollen germinates.Without their colorful corolla,flowers do not attract pollinators and are not fertilized.An adult grasshopper can consume a large corolla,about 2.5 inch
13、es long,in an hour.Caterpillars and seed beetles affect seed production directly.Caterpillars devour the ovaries,where the seeds are produced,and seed beetle larvae eat seeds as they burrow in developing fruits. 有一个例子向我们展示了被花外蜜腺吸引的蚂蚁如何保护牵牛花不被昆虫伤害的。北美 牵牛花的头号天敌昆虫主要吸食牵牛花的花朵和果实而不是叶子。因为草蜢吸食花朵，破坏 牵牛花的花冠或柱
14、头，而这正是接收花粉粒和花粉生长的地方，所以间接阻断了授粉和制造 种子。一旦花冠被破坏，花朵不能再吸引传份昆虫，因此不能受精。一个成年草蜢可以在不 到一个小时消耗一个 2.5 英寸的大型花冠。相比之下，毛毛虫和象鼻虫则是直接影响种子的 形成。毛毛虫毁坏子房，这是生产种子的地方。在果实成熟过程中，象鼻虫的幼虫进入果实 内部蚕食种子。 Extrafloral nectaries at the base of each sepal attract several kinds of insects,but 96 percent of them are ants,several different sp
15、ecies of them.When buds are still small,less than a quarter of an inch long,the sepal nectaries are already present and producing nectar.They continue to do so as the flower develops and while the fruit matures.Observations leave little doubt that ants protect morning glory flowers and fruits from t
16、he combined enemy force of grasshoppers,caterpillars,and seed beetles.Bentley compares the seed production of six plants that grew where there were no ants with that of seventeen plants that were occupied by ants.Unprotected plants bore only 45 seeds per plant,but plants occupied by ants bore 211 se
17、eds per plant.Although ants are not big enough to kill or seriously injure grasshoppers,they drive them away by nipping at their feet.Seed beetles are more vulnerable because they are much smaller than grasshoppers.The ants prey on the adult beetles,disturb females as they lay their eggs on developi
18、ng fruits,and eat many of the eggs they do manage to lay. 每个花萼底部的花外蜜腺可以吸引几种不同的昆虫，不过 96%都是蚂蚁，尽管种类会有 所不同。当蓓蕾还小时，已经有不到四分之一长的花萼蜜腺分泌花蜜了。随着花朵的发育和 果实变得成熟，花萼蜜腺仍然继续分泌花蜜。通过观察可以确定蚂蚁保护牵牛花的花朵和果 实不会受到草蜢、毛毛虫和象鼻虫的联合侵袭。宾利对比了六株生长在没有蚂蚁地域的植物 结出的果实和 17 株生长在有蚂蚁地域的植物结出的果实。结果发现 ： 不受蚂蚁保护的植物每 株只结出 45 个种子，而有蚂蚁保护的植物每株结出了 211 个
19、种子。尽管蚂蚁不够强大，不能 杀死或严重伤害草蜢，但是蚂蚁可以通过啃咬草蜢的脚驱赶它们。而比草蜢更小的象鼻虫则 更容易受到蚂蚁的攻击。蚂蚁以象鼻虫为食，干扰在果实上产卵的磁性象鼻虫，还能吃掉象 鼻虫的卵虫。 1.According to paragraph 1,floral nectar and extrafloral nectar are alike in that A)they are likely to be produced by the same plants B)they basically consist of the same chemical components C)the
20、y attract only insects that will defend the plant D)they are produced by the same parts of the plant Para.2Ants are portably the most frequent and certainly the most persistent defenders of plants.Since the highly active worker ants require a great deal of energy,plants exploit this need by providin
21、g extrafloral nectar that supplies ants with abundant energy.To return this favor,ants guard the nectaries,driving away or killing intruding insects that might compete with ants for nectar.Many of these intruders are herbivorous and would eat the leaves of the plants. 2.To say that ants are“persiste
22、nt”defenders of plants means that A)they defend plants against a wide variety of threats B)they continue to defend plants for as long as the plants are threatened C)they are successful defenders of plants D)they are easily observable defenders of plants 3.What can be inferred from paragraph 2 about
23、the ants that are attracted to the extrafloral nectaries? A)They do not eat the leaves of the plants that produce extrafloral nectar. B)They live almost entirely on extrafloral nectar. C)They spend most of their energy guarding extrafloral nectaries. D)They frequently fight among themselves over ext
24、rafloral nectar. Para.3Biologists once thought that secretion of extrafloral nectar has some purely internal physiological function,and that ants provide no benefit whatsoever to the plants that secrete it.This view and the opposing“ protectionist” hypothesis that ants defend plants had been dispute
25、d for over a hundred years when,in 1910,a skeptical William Morton Wheeler commented on the controversy.He called for proof of the protectionist view:that visitations of the ants confer protection on the plants and that in the absence of the insects a much greater number would perish or fail to prod
26、uce flowers or seeds than when the insects are present.That we now have an abundance of the proof that was called for was established when Barbara Bentley reviewed the relevant evidence in 1977,and since then many more observations and experiments have provided still further proof that ants benefit
27、plants. 4.According to paragraph 3,what was the position of the opponents of the “protectionist”hypothesis? A)Extrafloral nectar provides plants with a direct defense against attack by insects. B)Ants substantially benefit plants that secrete extrafloral nectar. C)The secretion of extrafloral nectar
28、 plays a role in the plants internal functioning. D)Ants visit plants that secrete extrafloral nectar as often as they visit plants that do not. 5.The word“skeptical”in the passage is closest in meaning to A)curious B)doubtful C)open-minded D)practical 6.Which of the sentences below best expresses t
29、he essential information in the highlighted sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information. A)We now have ample proof that ants benefit plants. B)Barbara Bentley has called for additional proof that ants benefit plants. C)In 1977 Bar
30、bara Bentley conducted research that proved that all prior studies were wrong. D)Proof that ants benefit plants will require many more observations and experiments. Para.4One example shows how ants attracted to extrafloral nectaries protect morning glories against attacking insects.The principal ins
31、ect enemies of the North American morning glory feed mainly on its flowers or fruits rather than its leaves.Grasshoppers feeding on flowers indirectly block pollination and the production of seeds by destroying the corolla or the stigma,which receives the pollen grains and on which the pollen germin
32、ates.Without their colorful corolla,flowers do not attract pollinators and are not fertilized.An adult grasshopper can consume a large corolla,about 2.5 inches long,in an hour.Caterpillars and seed beetles affect seed production directly.Caterpillars devour the ovaries,where the seeds are produced,a
33、nd seed beetle larvae eat seeds as they burrow in developing fruits. 7.According to paragraph 4,what effect does the destruction of the corolla have on plants? A)It leaves the seeds exposed and unprotected. B)It prevents the stigma from developing. C)It keeps pollen grains from attaching properly. D
34、)It prevents the flower from attracting pollinators. 8.The word“devour”in the passage is closest in meaning to A)attack B)eat C)damage D)prefer Para.5Extrafloral nectaries at the base of each sepal attract several kinds of insects,but 96 percent of them are ants,several different species of them.Whe
35、n buds are still small,less than a quarter of an inch long,the sepal nectaries are already present and producing nectar.They continue to do so as the flower develops and while the fruit matures.Observations leave little doubt that ants protect morning glory flowers and fruits from the combined enemy
36、 force of grasshoppers,caterpillars,and seed beetles.Bentley compares the seed production of six plants that grew where there were no ants with that of seventeen plants that were occupied by ants.Unprotected plants bore only 45 seeds per plant,but plants occupied by ants bore 211 seeds per plant.Alt
37、hough ants are not big enough to kill or seriously injure grasshoppers,they drive them away by nipping at their feet.Seed beetles are more vulnerable because they are much smaller than grasshoppers.The ants prey on the adult beetles,disturb females as they lay their eggs on developing fruits,and eat
38、 many of the eggs they do manage to lay. 9.What role does paragraph 5 play in the passage? A)It offers various kinds of evidence for the protectionist view. B)It presents the study that first proved that ants benefit plants. C)It explains how insects find sources of nectar. D)It presents information
39、 that partly contradicts the protectionist view. 10.The word“vulnerable”in the passage is closest in meaning to A)numerous B)harmful C)open to attack D)difficult to locate 11.According to paragraph 5,what did Bentleys comparative study show? A)Many more plants grew in places where ants were present
40、than where they were absent. B)The ants preferred plants with low seed production to plants with high seed production. C)The plants occupied by ants produced many more seeds than those that were not occupied by ants. D)The plants that grew in places without ants were much smaller and weaker than tho
41、se that grew in places where ants were present. 12.According to paragraph 5,ants defend morning glory plants from seed beetles in each of the following ways EXCEPT A)driving adult beetles off the plants by nipping at their feet B)catching and eating adult beetles C)eating beetle eggs they find on de
42、veloping fruits D)making it difficult for beetles to lay eggs on developing fruits 13.Look at the four squares【】that indicate where the following sentence could be added to the passage. Sometimes they capture the insects to feed their protein-hungry larvae. Where does the sentence best fit? Ants are
43、 portably the most frequent and certainly the most persistent defenders of plants.【 】 Since the highly active worker ants require a great deal of energy,plants exploit this need by providing extrafloral nectar that supplies ants with abundant energy.【】To return this favor,ants guard the nectaries,dr
44、iving away or killing intruding insects that might compete with ants for nectar.【】Many of these intruders are herbivorous and would eat the leaves of the plants.【】 14.Prose Summary Many plants have extrafloral nectaries that produce nectar even during periods in which the plant is not flowering. Ans
45、wer Choices A)Evolutionary history shows that plants that produce extrafloral nectar originated in the tropics. B)Extrafloral nectar has a higher concentration of sugar than floral nectar and is more attractive to ants and other insects. C)The protectionist hypothesis is that extrafloral nextar attr
46、acts ants,and that the ants,in order to preserve this energy-rich food source,attack insects that might harm the plant. D)Evidence accumulated during the twentieth century proved that ants provide significant benefits for plants with extrafloral nectaries. E)Research has shown that American morning
47、glory plants that are protected by ants produce significantly more seeds than morning glory plants that are not protected by ants. F)Ants generally ignore small insects,but they will eat the adults of large insect species as well as their eggs and larvae. Q1 正确答案：B 解析：根据题目关键词 alike 定位到原文 like floral
48、 nectar,extrafloral nectar consists mainly of water with a high content of dissolved sugars and,in some plants,small amounts of amino acids。 定位句的意思是说 extrfloral nectar(花外蜜腺) 和 floral nectar(花蜜)所含的组成物质是类似的， 只有 B 选项表述的 chemicals 能够概括这 句话所说的 water,sugar,acids.。 不要被 C 选项的表述误导，原文信息 all extrafloral nectar
49、ies attract insects that will defend the plant 说的只是 extrafloral nectaries 的特点。 Q2 正确答案：B 解析：persistent 意为“持久的，持续的，固执的，坚持不懈的” ，所以正确选项的表 述应该含有 continue for a long period of time 的意思,故选 B：they continue to defend plants for as long as the plants are threatened。 Q3 正确答案：A 解析：根据题目关键词 ants that are attracted to the extrfloral nectaries 定位到原 文信息为 To return this favor,ants guard the nectaries,driving away or killing intruding insects that might compete with ants for nectar,以及 Many of these intruders are herbivorous and would eat the leaves of the plants，所以蚂蚁做的事是保护植物不被 入侵的昆虫吃掉叶子，也就是说蚂蚁吃花蜜但是不吃叶子。 原文提