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托福阅读真题集锦〔六〕
PASSAGE 11
Plants are subject to attack and infection by a re 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
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parasite itself subsequently ceases togrow and is therefore restricted to one or a few cells around the entry theories have been put forward to explain the basis of hypersensitive resistance.
1. What does the passage mainly discuss?
The success of parasites in resisting plant defense mechanisms
Theories on active plant defense mechanisms
How plant defense mechanisms function
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Howthe immunesystem of animals and the defense mechanisms of plants differ
2. The phrase "subject to" in line 1 is closest in meaning to
susceptible to
classified by
attractive to
strengthened by
3. The word "puncture" in line 8 is closest in meaning to
pierce
pinch
surround
cover .
4. The word "which" in line 12 refers to
tissues
substances
barriers
(D) insects
Which of the following substances does the author mention as NOT necessarily bei