托福TPO38閱讀真題解析：Passage 3

TPO，即toefl Practice Online的首寫字母，就是托福在線練習的意思，TPO可以為考生提供全真的模擬考試環(huán)境和過往真題，而TPO題庫也是有著不斷的更新。在托福閱讀的備考過程中，除了大量的閱讀之外，全面了解托福閱讀的題型和解題方法也都是非常重要的環(huán)節(jié)。而對于很多備考托福的學生來說，TPO往往就是一個首先的備考材料。今天，小編就為大家?guī)�來托福TPO38閱讀真題解析：Passage 3。

托福TPO38閱讀Passage 3 真題解析 【在線咨詢】

Transgenic Plants

paragraph 1
1. According to paragraph 1, which of the following is true of transgenic plants that produce the protein Bt?
A. They are resistant to certain herbicides.
B. They grow best in the United States.
C. They were treated with the chemicals glyphosate.
D. They are resistant to destruction by insects.
答案：D選項正確

解析：本題根據(jù)題干給出的兩個關鍵詞transgenic plants和protein Bt定位到原文中的第一段，第一段里出題點在這半句話：they contain an insect-resistant gene that produces a protein called Bt toxin。這半句話的意思是含有Bt蛋白質基因的植物可以抵抗害蟲。選項D符合。選項A說它們可以抵抗除草劑，選項B說它們在美國生長地最好，選項C說它們被施加了一種農藥草甘膦，都不符合原文意思。選擇D。

paragraph 2
2. According to paragraph 2, supporters claim that producing transgenic plants enables farmers to
A. increase crop production by up to 21 percent
B. use fewer and less toxic chemicals
C. control weeds without the use of glyphosate
D. take advantage of more effective herbicides
答案：B選項正確

解析：本題根據(jù)題干給的關鍵詞enable farmers定位到這一句：On the positive side, proponents of transgenic crops argue that these crops are environmentally friendly because they allow farmers to use fewer and less noxious chemicals for crop production. 本句的大體意思是：轉基因作物的支持者說這些植物是環(huán)境友好的，因為它們可以讓使用的農藥量變少。選項B是正確的同義轉述。選項A說可以增加產量，選項C說可以不用草甘膦控制野草，選項D說可以利用更有效果的除草劑，都不符合原文。選擇B。

3. The word "persistent" in the passage in closest in meaning to
A. harmful
B. long lasting
C. expensive
D. hard to control
答案：B選項正確

解析：本題根據(jù)所考察的詞匯定位到原文中這一句：In addition, when glyphosate is used to control weeds, other, more persistent herbicides do not need to be applied. 本句的大意是：另外，草甘膦被用于控制雜草時，其他的更加效果持久的除草劑就不需要再用了。persistent的意思是長時間的。選項A是有害的，選項B是長期的持久的，選項C是貴的，選項D是難以控制的。選項B最貼合persistent的意思，選擇B。 

paragraph 3
4. Which of the following can be inferred about monarch caterpillars from paragraph 3?
A. They often cause damage to corn crops.
B. They are the only species that is immune to Bt toxin.
C. They are considered beneficial insects.
D. Their reactions to Bt pollen have not yet been studied.
答案：C選項正確

解析：本題根據(jù)題干所給關鍵詞monarch caterpillar進行定位，找到原文中這一句：For example, monarch caterpillars feeding on milkweed plants near Bt cornfields will eat some com pollen that has fallen on the milkweed leaves. for example告訴我們monarch caterpillar是作為例子去證實前一句所說的Bt plants have on nontarget organisms such as beneficial insects, worms, and birds that consume the genetically engineered crop的。所以monarch caterpillar在這里是作為有益處昆蟲出現(xiàn)的，選項C符合。其余三個選項原文中都沒有提到。選擇C。

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5. What conclusion does the author make in paragraph 3 about the effect of Bt plants on notarget organisms?
A. Bt toxins do not affect nontarget organisms because the toxins only harm pests that eat the leaves, stems, or fruit of the plants.
B. Bt plants have been shown in field studies to cause great harm to nontarget organisms.
C. Bt plants do not cause as much harm to nontarget species as the use of conventional pesticides.
D. Even if Bt toxins do not affect the insects that feed on the plants, they have harmful effects on birds that eat these insects.
答案：C選項正確

解析：本題的出題點在第五段最后兩句：However, field tests indicate that Bt corn is not likely to harm monarchs. Furthermore, the application of pesticides (the alternative to growing Bt plants) has been demonstrated to cause widespread harm to nontarget insects. 這兩句對比說明Bt作物不會傷害毛毛蟲，但是殺蟲劑的使用是會傷害它們這種非靶向物種的。選項C說Bt植物對非靶向物種的傷害比殺蟲劑小，正確。選項A說Bt物質不會傷害非靶向物種，錯誤，只是傷害比殺蟲劑小而已;選項B說Bt物質殺傷力非常大，錯誤，其實并不大;選項D說即使Bt物質不傷害以這種作物為食的昆蟲，但是會傷害鳥類，錯誤。選擇C。

paragraph 4
6. The word "perpetuated" in the passage is closest in meaning to
A. continued
B. reproduced
C. observed
D. spread
答案：A選項正確

解析：本題根據(jù)所考察的單詞定位到這一句：If the crop plants hybridize and reproduce with weedy relatives, then this herbicide-resistant gene will be perpetuated in the offspring. 本句大致意思是：如果農作物與雜草雜交，然后這種抗除草劑的基因就會一直保存在后代身上。perpetuate的意思是不朽，長存。選項A是持續(xù)的，選項B是再生產的，選項C是觀察的，選項D是傳播的。選項A最貼合perpetuate的意思。選擇A。

7. The word "scenario" in the passage is closest in meaning to
A. effect
B. problem
C. resistance
D. situation
答案：D選項正確

解析：本題根據(jù)所考察的單詞定位到這一句：This scenario is not likely to occur in many instances because there are no weedy relatives growing near the crop plant. 本句大致意思是：這種情況不容易廣泛發(fā)生，因為在這種作物周圍一般是沒有雜草存在的。scenario的意思是情景，場景，情況。選項A的意思是影響，選項B的意思是問題，選項C的意思是阻力，選項D的意思是場景。選項D最符合scenario的意思，選擇D。

8. Why does the author mention "mustard weed species" in the discussion of plants that hybridize?
A. To give an example of a weed that may become resistant to glyphosate due to hybridizing with a transgenic plant.
B. To argue that creating transgenic plants in the laboratory is not always necessary, as some can be created through hybridizing in the fields.
C. To provide evidence that competition from related species of plants can be a serious problem for transgenic plants.
D. To support the claim that it is difficult to determine whether or not a crop plant has been planted a safe distance from weedy relatives.
答案：A選項正確

解析：本題題干給的關鍵詞是mustard weed species和hybridize，帶著關鍵詞回溯原文，找到這里：For example, canola readily hybridizes with mustard weed species and could transfer its herbicide-resistant genes to those weeds. 結合前文，本句的大意是：例如canola這種作物就可以與mustard這種雜草雜交，把它的抗除草劑基因傳給這種雜草。所以作者在這里的意思是舉例雜交可以使得雜草具有抗除草劑的基因。選項A正確。選項B說為了論證沒必要創(chuàng)造轉基因作物，選項C說為了證明相關物種和轉基因作物的競爭很重要，選項D說為了支持很難把作物和雜草隔開一段安全距離種植，都是不合原文意思的。選擇A。

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paragraph 5
9. Paragraph 5 makes all of the following claims about Bt resistance in insect populations EXCEPT:
A. Regular use of Bt pesticides has not created resistant insect populations, so the use of Bt plants is probably safe as well.
B. The evolution of Bt-resistant insect populations will happen eventually if use of transgenic plants becomes widespread.
C. Because Bt plants are toxic at all times and in all tissues, they allow only Bt- resistant insects to survive and reproduce.
D. Planting nontransgenic plants alongside Bt plants may help Bt-susceptible insects to remain part of the population.
答案：A選項正確

解析：本題的出題點分布在整個第五段。選項A涉及到Bt殺蟲劑不會導致昆蟲產生抗性，所以具有Bt基因的作物的使用是安全的，不對，Bt基因作物的使用是有風險的，整段都在講這種作物使昆蟲產生抗藥性的事情;選項B涉及到We know that evolution will occur when transgenic plants grown on a large scale over a period of time，是這句話的同義轉述，正確;選項C是涉及到However, transgenic Bt plants express the toxin in all tissues throughout growing season. Therefore, all insects carrying genes that make them susceptible to the toxin will die.Bt基因的作物會殺死除了帶有抗性基因的所有昆蟲，正確;選項D 依據(jù)for example, planting nontransgenic border rows to provide a refuge for susceptible insects，種植不帶轉基因的作物使解決辦法之一，正確。選擇A。

paragraph 6
10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. The transgenic crop plants currently in use are probably far behind the transgenic plants of the future in terms of their sustainability.
B. Farmers who use transgenic crop plants are heading toward practices that allow natural resources to continually regenerate over the long run.
C. Transgenic crop plants may be used in place of other, more sustainable agricultural practices, and this is perhaps their biggest disadvantage.
D. Perhaps the most serious concern about the transgenic crop plants currently in use is the possibility that they may not be sustainable over the long run.
答案：D選項正確

解析：本題根據(jù)所考察的單詞定位到這一句：Perhaps the most serious concern about the transgenic crop plants currently in use is that they encourage farmers to move farther away from sustainable agricultural farming practices, meaning ones that allow natural resources to continually regenerate over the long run. 這句話的大體意思是：也許轉基因作物帶來的最嚴重問題是，它讓農民開始放棄可持續(xù)性的耕作方式，放棄了那種可以讓自然資源在長期自己再生的那種耕作方式。選項D是本句的同義轉述。選項A說現(xiàn)在用的轉基因作物比將來的可持續(xù)性差，原文中沒有提到;選項B說農民將要進行可持續(xù)的耕作活動，意思與這句話相悖;選項C說轉基因作物可以被用在更有持續(xù)性的地方，原文中沒有提及。選擇D。

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11. According to paragraph 6, a sustainable approach to weed and pest control includes all of the following EXCEPT
A. watching the fields closely to determine when weeds or pests are actually a problem
B. applying pesticides unless or until pesticides are needed
C. using only one type of herbicide throughout the growing season
D. planting nontransgenic crops
答案：C選項正確

解析：本題的選擇依據(jù)集中在第六段后半部分。選項A的依據(jù)是monitor the fields throughout the growing season，即全程監(jiān)控作物生長情況;選項B的依據(jù)是then apply a pesticide only if and when needed，即只在需要的時候使用殺蟲劑;選項D的依據(jù)是A more sustainable approach would be to plant nontransgenic corn，耕作無轉基因的作物。選項C說的一個耕作季節(jié)只用一種殺蟲劑，根據(jù)前文我們知道這樣很容易讓昆蟲剩下全是抗性的昆蟲，錯誤。選擇C。

12. The word "superficially" in the passage is closest in meaning to
A. in the opinion of experts
B. at the present moment
C. when done properly
D. without deeper analysis
答案：D選項正確

解析：本題根據(jù)所考察的單詞定位到這一句：Transgenics, at least superficially, simplify farming by reducing the choices made by the manager. 本句的大意是：轉基因，最起碼在表面上通過減少管理者的可選項而簡化了耕作過程(本句意思較抽象，具體而言是：選擇了具有哪種農藥抗性的作物，使用的農藥種類就固定了，只能用作物具有抗性的那一種，因此農民不需要再在多種農藥中選擇了)。superficially的意思是表面上。選項A是根據(jù)專家意見，選項B是在當前，選項C是當恰當?shù)刈鲆院螅�選項D是沒有更深的分析。選項D最貼合superficially的意思，選擇D。

13. Look at the four squares [■]that indicate where the following sentence could be added to the passage.
It is especially rare in the United States, where most transgenic plants are grown, because most of the crops grown in the United States originated elsewhere.
Where would the sentence best fit?
Click on a square [■] to insert the sentence in the passage.
答案：D選項正確

解析：本題需要先分析需要插入的句子：It is especially rare in the United States, where most transgenic plants are grown, because most of the crops grown in the United States originated elsewhere. 本句開頭的especially暗示了前文應該說到了一個比較廣泛的事情，這一句接著細化，繼續(xù)說明。帶著這個預設我們去一一嘗試四個可插入位置，發(fā)現(xiàn)最后一個合適。它前面一句講的是這種情況不大可能發(fā)生，需要插入句子接著說明在美國這種情況很少見，后面一句轉折說明但是某些情況下，這個問題會變得嚴重。三句話邏輯鏈條合理而且完整。選擇D。

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in summary because the express ideas that are not presented in the passage or are minor ideas in the passage. The Question is worth 2 points
Transgenic plants include genes from other organisms that make them resistant to glyphosate or toxic to insects.
Answers Choices
A. Proponents of transgenic plants argue that they reduce the use of harmful pesticides and allow the use of more environmentally friendly herbicides.
B. Use of transgenic plants may lead farmers to neglect more sustainable agricultural practices, and may also cause harm to nontarget organisms.
C. Over the long term, transgenic plants are likely to lose their glyphosate resistance through evolution and hybridization with nonresistant relatives.
D. Opponents of transgenic plants worry that resistance to glyphosate may spread to weeds and that resistance to Bt toxin may develop among insect pests.
E. One argument against Bt plants is that some of the most harmful pests are not Bt susceptible, making application of supplementary pesticides necessary.
F. Many of the problems identified with transgenic plants today will likely disappear as scientists design transgenic plants that are more ecologically friendly.
Drag your answer choices to the space where they belong. To remove an answer choice, double click on it.
答案：ABD選項正確

解析：本題需要依次分析每個選項。選項A說轉基因作物的支持者認為這些作物降低了有害殺蟲劑的使用，并且允許使用更加環(huán)境友好的除草劑，概括了第二段的內容，正確;選項B說轉基因作物的兩個壞處，概括了第三段和第六段的內容，正確;選項C認為時間一長，轉基因作物容易失去抗性，原文中沒有提到這個，錯誤;選項D說轉基因作物的反對者擔心抗藥基因傳入雜草中，概括了第四段的主要內容，正確;選項E說一些最有害的害蟲對于Bt物質是有抗性的，原文中沒有提到，錯誤;選項F說很多轉基因作物的問題在現(xiàn)在會消失，但是第六段只是提出了幾種解決辦法，并不能徹底解決問題，錯誤。綜合起來選擇A，B，D。

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