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 from 35 to 44.Bird migration is one of the most interesting yet least understood natural phenomena. Every fall birds from northern latitudes fly in groups to the warmer southern latitudes and then return north in the spring. Scientists agree on the main reasons for migration: to follow the food supply and to avoid harsh climate conditions. For example,...
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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 from 35 to 44.
Bird migration is one of the most interesting yet least understood natural phenomena. Every fall birds from northern latitudes fly in groups to the warmer southern latitudes and then return north in the spring. Scientists agree on the main reasons for migration: to follow the food supply and to avoid harsh climate conditions. For example, insects disappear during the cold months, prompting insect-dependent birds to fly south to warm areas where insects breed. No similar consensus has emerged, however, about how birds are able to navigate. Despite many recent experiments, bird experts still do not know how birds arrive at the same destinations every year and then find their way back home in the spring.
Some have suggested that birds find their way by following landmarks, such as rivers and mountain ranges. Experiments have confirmed that some species do follow such topographic features. But that method cannot explain how some birds travel at night. Other studies show that some nocturnal birds navigate by the stars. But that explanation cannot explain daytime migration or travel when the skies are cloudy.
The most popular explanation currently is that birds are guided by Earth’s magnetic poles. The mechanism by which that works has not yet been proved. One theory points to the fact that some birds’ contain magnetite, a naturally occurring magnetic compound consisting of iron oxide. Magnetite has been found in many animals, including birds. With magnets embedded in their brains, birds would be able to sense the magnetic fields of the North and South Poles.
A recent experiment with homing pigeons provided some evidence that magnetite does play a crucial role in migration. Homing pigeons are known to have the ability to return to their homes after being taken hundreds of miles away. Researchers found that they could train homing pigeons to recognize changes in a magnetic field. When a surrounding magnetic field was normal, the birds would gather at one end of a cage. But when the field’s polarity was altered, they hopped to the other end, suggesting that they were directing and responding to changes in the magnetic field.
Another theory has been offered to explain this sensitivity to magnetic poles, a theory that draws upon quantum mechanics, which is the study of how particles move inside an atom. It relies on the fact that electrons come in pairs that orbits the nucleus of an atom. The two electrons spin in opposite directions, creating two magnets that neutralize each other. But when molecules split and react with other molecules to form compounds, the electrons pairs may no longer spin in opposite directions. Instead, they may repel each other, as when two north ends of magnets are pressed together. The electrons struggle to change direction in order to achieve a stable state in which the two electrons again neutralize each other, giving off no magnetic field.
According to paragraph 1, insects influence bird migration in which of the following ways?
A. insects generate a magnetic field that birds can detect
B. Insects provide a food supply that exists only in warm climates
C. Birds follow the paths taken by flying insects
D. birds know when to migrate by a sudden increase in insect population
1. Scientists are able to explain the consequences of habitat (destroy) ________destruction___ _______ now.
2. Every year about 15,000 acres of fertile topsoil are washed away in Haiti, which has resulted in massive soil (erode) __________erosion__________
3. Cultural diversity make our country richer by making it a more (interest) ________interesting________ place to live.
4. In every culture, there are (base) ____________basic_________ standards for social (interact) _________interaction________ such as
5. The (consume)__________consumption___________ of fossil fuels has gradually increased in many countries which is concern for many environmentalists.
6. The increase in cases of skin cancer has been recorded in parallel with ozone layer (deplete) ___________depletion___________
7. Harry asked for a _______receipt____ _______ and the casher gave him one ( receive )
8. __________interestingly_ _______ , my father used to go to school with your father. ( interest )
9. Do you think you have the ________ability___ _______ to pass the test ( able )
10. They didn’t give Gary the job as he was _____inexperienced______ _______ ( experience )
1. Scientists are able to explain the consequences of habitat (destroy) _destruction__ now.
2. Every year about 15,000 acres of fertile topsoil are washed away in Haiti, which has resulted in massive soil (erode) __erosion____
3. Cultural diversity make our country richer by making it a more (interest) ___interesting ____ place to live.
4. In every culture, there are (base) ____basic_ standards for social (interact) __interaction_____ such as…
5. The (consume)____consumption____ of fossil fuels has gradually increased in many countries which is concern for many environmentalists.
6. The increase in cases of skin cancer has been recorded in parallel with ozone layer (deplete) __depletion_____
7. Harry asked for a ___receipt___ and the casher gave him one ( receive )
8. ___Interestingly___ , my father used to go to school with your father. ( interest )
9. Do you think you have the ____ability__ to pass the test ( able )
10. They didn’t give Gary the job as he was ____inexperienced_____ _______ ( experience )