托福阅读真题+题目+答案：The Decline of the Arctic Fox in Scandinavia

托福阅读真题+题目+答案：The Decline of the Arctic Fox in Scandinavia

The arctic fox has lived in the Scandinavian countries of Norway, Finland, and Sweden since the last Ice Age, which ended more than10,000 years ago. ⬛Today, however, the arctic fox in Scandinavia is in severe trouble. Despite intense conservation efforts, its numbers have been radically declining.⬛ Why this most resourceful of species has been unable to rebound since hunting it was prohibited is not altogether clear.⬛

1.The word “prohibited" in the passage is closest in meaning to

O discouraged

O forbidden

O uncommon

O reduced

One possibility is that the animals have gone through what biologists refer to as a population bottleneck. ⬛Such bottlenecks occur when the number of animals in a given population is reduced to the point where inbreeding enables the enhanced proliferation of genes that may be detrimental to a species' overall fitness (ability to survive). A related hypothesis is that the arctic foxes had lost their genetic advantage owing to the spread of genes from selectively bred foxes that escaped from farms. Captive-raised foxes are known to have escaped, and recent genetic studies from Norway have shown that such interbreeding between farm-bred foxes and foxes in the wild has indeed taken place. While these results are being viewed as potential future trouble, there is still no indication that they explain past difficulties. The number of crossover genes detected in the Norwegian study was small, suggesting that mixing between wild and escaped foxes is a recent occurrence.

2.The word "proliferation" in the passage is closest in meaning to

O relationship

O evolution

O spread

O protection

3.According to paragraph 2, why do scientists believe that mixing between wild and escaped foxes cannot explain past difficulties?

O There is no indication that farm-bred foxes and foxes in the wild have interbred.

O The mixing of genes is minimal and therefore probably began recently.

O The number of farm-bred foxes that have escaped is still small.

O Introducing crossover genes generally gives a species a genetic advantage.

4.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

O Changes in the environment might be to blame because wolves also disappeared from most of Norway and Sweden during the twentieth century.

O Wolves that for thousands of years filed the role of top predator throughout Scandinavia disappeared there after hundreds of years of persecution.

O One early idea was that the absence of wolves, which had been the top predator throughout Scandinavia until they nearly disappeared in the twentieth century, might be to blame.

O One of the earliest ideas was that changes in the environment might be to blame for the disappearance of wolves from most of Norway and Sweden during the twentieth century.

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