2019年11月9日托福阅读真题+题目+答案：How Aquatic Insects Remain Unseen by Predators

2019年11月9日托福阅读真题+题目+答案：How Aquatic Insects Remain Unseen by Predators

As with most small animals, aquatic insects often use camouflage to help them escape the notice of predators, and over the years a great deal of research and experimentation has gone into studying the various ways they do this, and why, and to what extent they are effective. Camouflage is, in essence, a way of trying to be invisible. Whereas most insects blend in with the background, the light sand of a beach, the dark bark of a tree, or the green of a leaf, some phantom midge larvae are virtually transparent and almost truly invisible. The only phantom midge that lives in certain Swedish pools occupied by fish is almost completely transparent.When Jan Stenson removed the fish from these pools, not only did this species become more abundant, but it was joined by another, less transparent, yellowish-brown species that Stenson thought would not survive in the presence of fish, because it is darker and more visible. He tested his idea by presenting fish in tanks with both species of phantom midge. The fish almost always ate the darker ones and virtually ignored the more transparent ones. But the darker species was also more conspicuous because of its activity.Did the fish attack the darker midges because of their color or because of their more energetic movements? Stenson found the answer by giving the fish a choice between naturally dark larvae and transparent larvae stained to resemble them. The fish attacked both species equally, although the naturally dark larvae were more active.
1.The word “essence” in the passage is closest in meaning to

A.without doubt

B.among other things

C.in some cases

D.basically

2.The word “resemble” in the passage is closest in meaning to

A.identify

B.keep track of

C.look like

D.contrast with

3.Why does the author mention that "the naturally dark larvae were more active"?

A.To confirm that the fish were attracted to the darker midges by their color and not by their activity

B.To raise the possibility that staining the midges may have had an effect on the way they moved

C.To help explain why, in the first experiment, the fish had virtually ignored the transparent species and had mainly eaten the darker ones

D.To emphasize that even after being stained. the transparent larvae were still not as active as the naturally dark larvae

4.According to paragraph 1, Jan Stenson was interested in examining which of the following TWO questions? To receive credit, you must select TWO answers.

A.Could darker species of phantom midges survive in certain ponds where fish were found?

B.Why are phantom midges almost completely invisible in water?

C.What exactly caused fish to attack darker species of phantom midges?

D.Why are darker species of midges more active than lighter colored ones?

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