proficiency exam samples - Text 4 Read the text and choose...

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Text 4. (Questions 54 – 62) Read the text and choose the best alternative according to the information in it. It’s a sound you will probably never hear, a sickened tree sending out a distress signal. But a group of scientists has  heard the cries, and they think some insects also hear the trees and are drawn to  them  like vultures to a dying animal. Researchers with the U.S. Forest Service fastened sensors to the bark of drought-stricken trees and clearly heard  distress calls. According to one of the scientists, most  parched  trees transmit their  plight  in the 50- to 500-kilohertz range.  (The unaided human ear can detect no more than 20 kilohertz.) Red oak, maple, white pine, and birch all make slightly different  sounds in the form of vibrations at the surface of the wood. The scientists think that the vibrations are created when the water columns inside tubes that run the length of the tree  break, a result of too little water flowing through them. These  fractured  columns send out distinctive vibration patterns.  Because some insects communicate at ultrasonic frequencies,  they  may pick up the trees’ vibrations and attack the weakened  trees. Researchers are now running tests with potted trees that have been deprived of water to see if the sound is what attracts  the insects. “Water-stressed trees also smell differently from other trees, and they experience thermal changes, so insects could be  responding to something other than sound,” one scientist said. THIS MATERIAL HAS BEEN PRODUCED ONLY FOR PRACTISE PURPOSES. 1 5 5 10
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A A A A A A A A A A A A A A A ITU PREP. PROGRAMME PROFICIENCY EXAM JULY 23, 2004 54. Which of the following is the main topic of the passage? a) the vibrations produced by insects b) the mission of the U.S. Forest Service c) the effect of insects on trees d) the sounds made by trees 55 . The word “ them ” in line 3 refers to __________. 56 . The word “ parched ” in line 6 is closest in meaning to __________.
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