Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 43 to 50.

     It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be adapted. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species.

     The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions many species became extinct at the same time - a mass extinction. One of the best-known examples of mass extinction occurred 65 million years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass extinctions can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, even affect organisms not living in the oceans. Such a change would probably lead to a mass extinction.

     One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intense every 26 million years. The periodic extinction might be due to intersection of the earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of essentially random events.

 

Why is "plankton" mentioned?

Whether it's English __________ mathematics, at Exeter we call our classes Harkness classes and our teachers Harkness teachers.

Mark the letter A, B, C or D to indicate the word that differs from the other three in the position of the primary stress in each of the following questions

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42.

     A rather surprising geographical feature of Antarctica is that a huge freshwater, one of the world's largest and deepest, lies hidden there under four kilometers of ice. Now known as Lake Vostok, this huge body of water is located under the ice block that comprises Antarctica. The lake is able to exist in its unfrozen state beneath this block of ice because its waters are warned by geothermal heat from the earth's core. This thick glacier above Lake Vostok actually insulates it from frigid temperatures (the lowest ever recorded on Earth) on the surface.

     The lake was first discovered in the 1970s while a research team was conducting an aerial survey of the area. Radio waves from the survey equipment penetrated the ice and revealed a body of water of indeterminate size. It was not until much more recently that data collected by satellite made scientists aware of the tremendous size of the lake; satellite-borne radar detected an extremely flat region where the ice remains level because it is floating on the water of the lake.

     The discovery of such a huge fresh water lake trapped under Antarctica is of interest to the scientific community because of the potential that the lake contains ancient microbes that have survived for thousands upon thousands of years, unaffected by factors such as nuclear fallout and elevated ultraviolet light that have affected organisms in more exposed areas. The downside of the discovery, however, lies in the difficulty of conducting research on the lake in such a harsh climate and in the problems associated with obtaining uncontaminated samples from the lake without actually exposing the lake to contamination. Scientists are looking for possible ways to accomplish this.

The paragraph following the passage most probably discusses _________.

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 43 to 50.

     It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be adapted. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species.

     The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions many species became extinct at the same time - a mass extinction. One of the best-known examples of mass extinction occurred 65 million years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass extinctions can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, even affect organisms not living in the oceans. Such a change would probably lead to a mass extinction.

     One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intense every 26 million years. The periodic extinction might be due to intersection of the earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of essentially random events.

In paragraph 3, the author makes which of the following statements about a species' survival?

Mark the letter A, B, C or D to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 43 to 50.

     It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be adapted. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species.

     The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions many species became extinct at the same time - a mass extinction. One of the best-known examples of mass extinction occurred 65 million years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass extinctions can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, even affect organisms not living in the oceans. Such a change would probably lead to a mass extinction.

     One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intense every 26 million years. The periodic extinction might be due to intersection of the earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of essentially random events.

According to paragraph 2, evidence from fossils suggests that .....

The band is planning to go on _______ in Europe and Asia next year.