『新东方在线托福阅读』为托福考生准备了ETS托福TPO/Official 38 Passage 3阅读练习：Why does the author mention “mustard weed species” in the discussion of plants that hybridize?真题题目及答案解析，TPO/Official 38 Passage 3阅读原文范文音频翻译

托福TPO/Official 38 Passage 3阅读原文Why does the author mention “mustard weed species” in the discussion of plants that hybridize?题目答案及解析-新东方托福官方网校手机版

从病毒到人类，几乎任何生物体的基因现在都可以植入植物，从而创造出所谓的转基因植物。

Genes from virtually any organism, from viruses to humans, can now be inserted into plants, creating what are known as transgenic plants.

现在全世界用于农业的转基因作物大约有1.09亿英亩，其中68%在美国。

Now used in agriculture, there are approximately 109 million acres of transgenic crops grown worldwide, 68 percent of which are in the United States.

最常见的转基因作物是大豆、玉米、棉花和油菜。

The most common transgenic crops are soybeans, corn, cotton, and canola.

最常见的情况是，这些植物要么含有抗除草剂草甘膦的基因，要么含有抗虫基因，产生一种名为Bt毒素的蛋白质。

Most often, these plants either contain a gene making them resistant to the herbicide glyphosate or they contain an insect-resistant gene that produces a protein called Bt toxin.

从积极的方面来看，转基因作物的支持者认为这些作物是环境友好型的，因为它们允许农民在农作物生产中使用更少、更无害的化学物质。

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.

例如，关于Bt棉花（产生Bt毒素的转基因棉花）的杀虫剂使用量减少了21%。

For example, a 21 percent reduction in the use of insecticide has been reported on Bt cotton (transgenic cotton that produces Bt toxin).

此外，当草甘膦被用来控制杂草时，其他更持久的除草剂就不需要使用了。

In addition, when glyphosate is used to control weeds, other, more persistent herbicides do not need to be applied.

从消极的方面来说，反对转基因作物的人认为，在大规模种植转基因作物之前，有许多问题需要回答。

On the negative side, opponents of transgenic crops suggest that there are many questions that need to be answered before transgenic crops are grown on a large scale.

其中一个问题涉及Bt作物对非目标生物的影响，如益虫、蠕虫和食用转基因作物的鸟类。

One question deals with the effects that Bt plants have on nontarget organisms such as beneficial insects, worms, and birds that consume the genetically engineered crop.

例如，黑脉金斑蝶幼虫以Bt玉米地附近的马利筋植物为食，会吃掉掉在马利筋叶子上的一些玉米花粉。

For example, monarch caterpillars feeding on milkweed plants near Bt cornfields will eat some corn pollen that has fallen on the milkweed leaves.

实验室研究表明，毛虫可以死于食用Bt花粉。

Laboratory studies indicate that caterpillars can die from eating Bt pollen.

然而，田间试验表明，Bt玉米不太可能危害帝王蝶。

However, field tests indicate that Bt corn is not likely to harm monarchs.

此外，农药的应用（Bt作物的替代物）已被证明会对非目标昆虫造成广泛的危害。

Furthermore, the application of pesticides (the alternative to growing Bt plants) has been demonstrated to cause widespread harm to nontarget insects.

另一个悬而未决的问题是抗除草剂基因是否会进入杂草种群。

Another unanswered question is whether herbicide-resistant genes will move into the populations of weeds.

农作物有时生长在杂草也生长的地方。

Crop plants are sometimes grown in areas where weedy relatives also live.

如果作物与杂草亲戚杂交并繁殖，那么这种抗除草剂基因将在后代中得以延续。

If the crop plants hybridize and reproduce with weedy relatives, then this herbicide-resistant gene will be perpetuated in the offspring.

这样，耐药基因就可以进入杂草种群。

In this way, the resistant gene can make its way into the weed population.

如果发生这种情况，农民就不能再使用例如草甘膦这样的（除草剂）来杀死杂草。

If this happens, a farmer can no longer use glyphosate, for example, to kill those weeds.

这种情况在许多情况下不太可能发生，因为没有杂草类植物生长在农作物附近。

This scenario is not likely to occur in many instances because there are no weedy relatives growing near the crop plant.

然而，在某些情况下，它可能成为一个严重的问题。

However, in some cases, it may become a serious problem.

例如，油菜很容易与芥菜杂交，并能将其抗除草剂基因转移到这些杂草上。

For example, canola readily hybridizes with mustard weed species and could transfer its herbicide-resistant genes to those weeds.

我们知道，当转基因植物在一段时间内大规模生长时，进化就会发生。

We know that evolution will occur when transgenic plants are grown on a large scale over a period of time.

特别值得关注的是抗Bt毒素昆虫种群的发展。

Of special concern is the development of insect populations resistant to the Bt toxin.

这种杀虫剂已经在植物上使用了几十年，却没有出现抗药昆虫群。

This pesticide has been applied to plants for decades without the development of insect-resistant populations.

然而，转基因Bt植物在整个生长季节的所有组织中都表现出这种毒素。

However, transgenic Bt plants express the toxin in all tissues throughout the growing season.

因此，所有携带对毒素敏感基因的昆虫都会死亡。

Therefore, all insects carrying genes that make them susceptible to the toxin will die.

这样就只剩下那些基因上有抵抗力的昆虫来维持它们的种群。

That leaves only the genetically resistant insects alive to perpetuate the population.

当这些有抵抗力的昆虫交配时，它们将产生大量的后代，这些后代能够在Bt毒素的存在下存活下来。

When these resistant insects mate, they will produce a high proportion of offspring capable of surviving in the presence of the Bt toxin.

农民正试图通过种植非转基因作物来减缓Bt作物中昆虫抗性的发展，为易感昆虫提供避难所。

Farmers are attempting to slow the development of insect resistance in Bt crops by, for example, planting nontransgenic border rows to provide a refuge for susceptible insects.

这些昆虫可能使Bt的易感性留在种群中。

These insects may allow Bt susceptibility to remain in the population.

也许对目前使用的转基因作物最严重的担忧是，它们使得农民远离可持续的农业耕作方式，也就是那些让自然资源在长期内不断再生的方式。

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.

转基因，至少在表面上，通过减少管理者的选择来简化农业。

Transgenics, at least superficially, simplify farming by reducing the choices made by the manager.

种植一种抗草甘膦作物，使得农民在这个季节使用这种除草剂，而可能不使用所有其他除草剂和其他控制杂草措施。

Planting a glyphosate-resistant crop commits a farmer to using that herbicide for the season, probably to the exclusion of all other herbicides and other weed-control practices.

使用Bt转基因技术的农民可能觉得没有必要遵循综合害虫管理措施，即使用益虫和及时施用杀虫剂来控制害虫。

Farmers who use Bt transgenics may not feel that they need to follow through with integrated pest-management practices that use beneficial insects and timely applications of pesticides to control insect pests.

一种更可持续的方法是种植非转基因玉米，在整个生长季节监测田地，然后只在需要的时候使用杀虫剂。

A more sustainable approach would be to plant nontransgenic corn, monitor the fields throughout the growing season, and then apply a pesticide only if and when needed.

According to paragraph 1, which of the following is true of transgenic plants that produce the protein Bt?

According to paragraph 2, supporters claim that producing transgenic plants enables farmers to

The word “persistent” in the passage is closest in meaning to

Which of the following can be inferred about monarch caterpillars from paragraph 3 ?

What conclusion does the author make in paragraph 3 about the effect of Bt plants on nontarget organisms?

The word “perpetuated” in the passage is closest in meaning to

The word “scenario” in the passage is closest in meaning to

Why does the author mention “mustard weed species” in the discussion of plants that hybridize?

Paragraph 5 makes all of the following claims about Bt resistance in insect populations EXCEPT:

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.

According to paragraph 6, a sustainable approach to weed and pest control includes all of the following EXCEPT

The word “superficially” in the passage is closest in meaning to

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 add the sentence to the passage.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Transgenic Plants Genes from virtually any organism, from viruses to humans, can now be inserted into plants, creating what are known as transgenic plants. Now used in agriculture, there are approximately 109 million acres of transgenic crops grown worldwide, 68 percent of which are in the United States. The most common transgenic crops are soybeans, corn, cotton, and canola. Most often, these plants either contain a gene making them resistant to the herbicide glyphosate or they contain an insect-resistant gene that produces a protein called Bt toxin. 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. For example, a 21 percent reduction in the use of insecticide has been reported on Bt cotton (transgenic cotton that produces Bt toxin). In addition, when glyphosate is used to control weeds, other, more persistent herbicides do not need to be applied. On the negative side, opponents of transgenic crops suggest that there are many questions that need to be answered before transgenic crops are grown on a large scale. One question deals with the effects that Bt plants have on nontarget organisms such as beneficial insects, worms, and birds that consume the genetically engineered crop. For example, monarch caterpillars feeding on milkweed plants near Bt cornfields will eat some corn pollen that has fallen on the milkweed leaves. Laboratory studies indicate that caterpillars can die from eating Bt pollen. 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. Another unanswered question is whether herbicide-resistant genes will move into the populations of weeds. Crop plants are sometimes grown in areas where weedy relatives also live. If the crop plants hybridize and reproduce with weedy relatives, then this herbicide-resistant gene will be perpetuated in the offspring.  In this way, the resistant gene can make its way into the weed population.  If this happens, a farmer can no longer use glyphosate, for example, to kill those weeds.  This scenario is not likely to occur in many instances because there are no weedy relatives growing near the crop plant.  However, in some cases, it may become a serious problem. For example, canola readily hybridizes with mustard weed species and could transfer its herbicide-resistant genes to those weeds. We know that evolution will occur when transgenic plants are grown on a large scale over a period of time. Of special concern is the development of insect populations resistant to the Bt toxin. This pesticide has been applied to plants for decades without the development of insect-resistant populations. However, transgenic Bt plants express the toxin in all tissues throughout the growing season. Therefore, all insects carrying genes that make them susceptible to the toxin will die. That leaves only the genetically resistant insects alive to perpetuate the population. When these resistant insects mate, they will produce a high proportion of offspring capable of surviving in the presence of the Bt toxin. Farmers are attempting to slow the development of insect resistance in Bt crops by, for example, planting nontransgenic border rows to provide a refuge for susceptible insects. These insects may allow Bt susceptibility to remain in the population. 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.Transgenics, at least superficially, simplify farming by reducing the choices made by the manager. Planting a glyphosate-resistant crop commits a farmer to using that herbicide for the season, probably to the exclusion of all other herbicides and other weed-control practices. Farmers who use Bt transgenics may not feel that they need to follow through with integrated pest-management practices that use beneficial insects and timely applications of pesticides to control insect pests. A more sustainable approach would be to plant nontransgenic corn, monitor the fields throughout the growing season, and then apply a pesticide only if and when needed.