托福阅读辅导:老托福阅读真题及答案passage11

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老托福阅读文本 passage11

Plants are subject to attack and infection by a remarkable variety of symbiotic species and have evolved a diverse array of mechanisms designed to frustrate the potential colonists. These can be divided into preformed or passive defense mechanisms and inducible or active systems. Passive plant defense comprises physical and chemical barriers that prevent entry of pathogens, such as bacteria, or render tissues unpalatable or toxic to the invader. The external surfaces of plants, in addition to being covered by an epidermis and a waxy cuticle, often carry spiky hairs known as trichomes, which either prevent feeding by insects or may even puncture and kill insect larvae. Other trichomes are sticky and glandular and effectively trap and immobilize insects.

If the physical barriers of the plant are breached, then preformed chemicals may inhibit or kill the intruder, and plant tissues contain a diverse array of toxic or potentially toxic substances, such as resins, tannins, glycosides, and alkaloids, many of which are highly effective deterrents to insects that feed on plants. The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids that normally repel potential pests. Other possible chemical defenses, while not directly toxic to the parasite, may inhibit some essential step in the establishment of a parasitic relationship. For example, glycoproteins in plant cell walls may inactivate enzymes that degrade cell walls. These enzymes are often produced by bacteria and fungi.

Active plant defense mechanisms are comparable to the immune system of vertebrate animals, although the cellular and molecular bases are fundamentally different. Both, however, are triggered in reaction to intrusion, implying that the host has some means of recognizing the presence of a foreign organism. The most dramatic example of an inducible plant defense reaction is the hypersensitive response. In the hypersensitive response, cells undergo rapid necrosis — that is, they become diseased and die — after being penetrated by a parasite; the parasite itself subsequently ceases to grow and is therefore restricted to one or a few cells around the entry site. Several theories have been put forward to explain the basis of hypersensitive resistance.

老托福阅读题目 passage11

1. What does the passage mainly discuss?

(A) The success of parasites in resisting plant defense mechanisms

(B) Theories on active plant defense mechanisms

(C) How plant defense mechanisms function

(D) How the immune system of animals and the defense mechanisms of plants differ

2. The phrase "subject to" in line 1 is closest in meaning to

(A) susceptible to

(B) classified by

(C) attractive to

(D) strengthened by

3. The word "puncture" in line 8 is closest in meaning to

(A) pierce

(B) pinch

(C) surround

(D) cover .

4. The word "which" in line 12 refers to

(A) tissues

(B) substances

(C) barriers

(D) insects

5. Which of the following substances does the author mention as NOT necessarily being toxic to the Colorado beetle?

(A) resins

(B) tannins

(C) glycosides

(D) alkaloids

6. Why does the author mention "glycoproteins" in line 17?

(A) to compare plant defense mechanisms to the immune system of animals

(B) to introduce the discussion of active defense mechanisms in plants

(C) to illustrate how chemicals function in plant defense

(D) to emphasize the importance of physical barriers in plant defense

7. The word "dramatic" in line 23 could best be replaced by

(A) striking

(B) accurate

(C) consistent

(D) appealing

8. Where in the passage does the author describe an active plant-defense reaction?

(A) Lines 1-3

(B) Lines 4-6

(C) Lines 13-15

(D) Lines 24-27

9. The passage most probably continues with a discussion of theories on

(A) the basis of passive plant defense

(B) how chemicals inhibit a parasitic relationship.

(C) how plants produce toxic chemicals

(D) the principles of the hypersensitive response.

老托福阅读答案 passage11

正确答案： CAABD CADD

托福阅读技巧：词汇题应对方法

为什么很多考生会对词汇题束手无措?一方面是因为考生的词汇量达不到，OG中词汇题的解释里有一句话，there is no “list of words” that must be tested. 这句话就告诉考生死了那条心去背所谓的大纲词汇，因为没有大纲，而考试中要考查到的单词可能是来自牛津字典或朗文字典中的任何一个单词，范围大的离谱;而另一方面则是因为有的考生没有学会从上下文或者从语法结构去猜测词义。

因为OG中的解释还有一句a word might have more than one meaning, but in the reading passage, only one of those meaning is relevant. 所以很有可能考生在考试中所碰到的词汇并不是已经让人熟知的第一词义，而是要根据语境上下文推断出的第二词义甚至是第三词义，所以又对考生做题增加了难度。最可悲的是不仅文章中的单词意思不知道，连4个选项中的单词都有不认识不熟悉的，这样的结果就只能是乱猜一气，听天由命全凭运气，当然考试结果也不会好。所以在此将给考生一点准备新托福阅读考试词汇题的建议和解题方法，希望能给考生攻克词汇题给予一些帮助。

Tip: 单词记忆

单词记忆主要就是背单词。背单词是很多同学觉得非常痛苦的事情，经常会有学生来问药怎么背，背了一些又马上忘了另外一些。所以关于如何去背单词，在这里有几点建议：

1、利用零散的时间背单词。利用零散的时间背单词可以使用单词卡片。不过，为了保证效率，首先要确定哪些单词需要记忆。理论上，单词量越多越好。实际上，如果一味贪多，结果容易打疲劳战，而且效率低。所以，只记那些常考的核心词汇，而对于那些不太常用的学科名词、物质名词一般加以忽略。

2、进行高频率的重复，建议把重复的周期控制在7天以内。具体说来，就是每天背100个单词，将过一遍这些单词的时间控制在半个小时以内，每天过4遍，第二天再过一遍前一天的。如果程度不是很好的同学可以压缩到50个左右，但尽量不要低于50个。单词材料可以找一些相关的新托福阅读词汇书，或者是以往考过的词汇题内容。

把背单词和阅读相结合。广泛的阅读也是增加词汇量的一种方法，并且能够在阅读中加强对已经背过的单词的记忆。当一篇文章的生词量在5%左右的时候，这些生词的词义是可推的。所以我们在选择阅读材料的时候，应尽量将单词量控制在10%左右。单词太多，看不懂文章，太少又起不到提高的作用。相关材料可以上一些网站看，例如economist, national geographic等等。

托福阅读辅导:老托福阅读真题及答案 passage11