HUGEdu®新TOEFL模拟考试

5. Which of the following statements most accurately describes the relationship of paragraph 3 to paragraph 2?

  • A. Paragraph 2 explains the causes of the spruce bark beetle epidemic in Alaska, and paragraph 3 discusses the chain of events that occurred as a result of that epidemic.
  • B. Paragraph 2 shows that warming air temperatures can affect a large number of species, and paragraph 3 shows that warming soil temperatures can have even greater effects.
  • C. Paragraph 2 discusses one explanation for the disappearance of spruce trees from a part of Alaska, but paragraph 3 shows that an alternative explanation is more likely to be correct.
  • D. Paragraph 2 describes the negative consequences of climate warming for some species, but paragraph 3 shows that there are also some positive consequences for these same species.

6. According to paragraph 3, a decline in the vole population in Alaska may have which TWO of the following consequences  To receive credit, you must select TWO answer choices.

  • A. Some predators may have less to eat.
  • B. Hawk and red squirrel populations may be more successful.
  • C. Plants may find it more difficult to absorb water and nutrients.
  • D. Mycorrhizal fungi numbers may increase.

Paragraph 3

In the late 1990s, the effects of the bark beetle epidemic rippled throughout Alaska’s white spruce ecosystem and affected virtually every population of living organisms, but not all of the impacts were negative. Fewer spruce trees meant a sunnier area in the forest below the treetops, which allowed grasses to move in and take hold. The grasses, in turn, changed the soil temperature, making the environment more friendly for some other types of vegetation. Animals that feed on grasses, including moose, elk, and some birds, also benefited. But the beetle infestation was bad news for organisms that rely on white spruce for their habitat, like hawks, owls, red squirrels, and voles. Voles a type of small, mouselike rodent are an especially vital part of the ecosystem because they help spread mycorrhizal fungi, which attach to the roots of plants and help them take in water and nutrients. Voles are also an important food for a number of predators.

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