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 vulture to a dying animal. Researchers with the US Department of Agriculture’s Forest Service fastened sensors to the bark of drought-stricken trees clearly heard distress calls. According to one of the scientists, most parched trees transmit their plight in the 50-hertz to 50-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 along the length of the tree break, a result of too little water following through them. These fractured columns send out distinctive vibration pattems. Because some insects communicate at ultrasonic frequencies, they may pick up the trees' vibration 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.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions

All the following are mentioned as possible factors in drawing insects to weakened trees EXCEPT .............

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• The writer himself __________ .

• The word "drastically" in line 21 is closest in meaning to ..........

• The word “They” in paragraph 2 refers to ...............

ZUNIA12

• How did John feel about his fears in the end?

• All of the following are TRUE about long – term memory EXCEPT that ..........

• What happens to nitrogen in body tissues if a diver ascends too quickly?

• What does the author imply about the rate hummingbirds’ wings beat?

• The phrase “more achievement oriented” in the paragraph 6 is closest in meaning to ______.

• The word “constituting” is closest in meaning to .........

• The expression “Curiously enough” is used because the author finds it strange that ............

• Which of the following phrases best explains the meaning of the word “verbal”?

• The first songs of the Beatles were ................

• According to the passage, the depression of the 1930's caused which of the following?

• Which of the following is NOT true about humpback whale music?

• According to the passage, which of the following statements is NOT true?

• According to the passage, why someone would choose to drink tea instead of coffee?

• Throughout the passage, the author implies that the Mandans _____.

• The word “There” in paragraph 5 refers to ____.

• In the second paragraph, the word “stored” is closest in meaning to _________.

• Which of the following properties is NOT mentioned as protected by copyright?