2019年11月10日托福阅读真题+题目+答案：Sea Turtle Hatching strategies for Navigation

2019年11月10日托福阅读真题+题目+答案：Sea Turtle Hatching strategies for Navigation

Sea turtles’ eggs are laid at night to minimize the likelihood of their discovery by predators, and the offspring, when ready to emerge from their eggshells and dig their way out of the sand, hatch at night for the same reason. Since the offspring are especially vulnerable immediately after hatching, it is vital for them to get to the sea as soon as possible. Turtle hatchlings use a number of cues to tell them where the sea is.

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

A. Sea turtle eggs are laid at night and hatch at night for the same reason.

B. To minimize the likelihood of their discovery by predators, sea turtle hatchlings dig their way out of the sand at night.

C. To minimize the likelihood of discovery by predators, sea turtle eggs are laid and hatch at night.

D. Eggs that laid at night and offspring that emerge from the eggs at night are less likely to be discovered by predators

The most important cue seems to be light. The night sky is usually brightest over the sea. Cover a turtle hatchling’s eyes, and it cannot find the sea even if there is other information available, such as a downward slope of the sand toward the water’s edge. The hatchlings respond to light cues covering a vertical range of only about 30°above the horizon or, depending on the species, even less. Responding only to lights that are close to the horizon decreases the risk that hatchlings will become confused. They seem less attracted to yellow light than to other colors—loggerhead turtles show an aversion to yellow light—and this preference may keep them from becoming disoriented by the rising Sun.

2. In paragraph 2, why does the author provide the information that sea turtle hatchlings cannot find the sea when their eyes are covered?

A. To identify a major reason that such turtles might not reach the sea

B. To support the claim that light is an important directional cue for such turtles

C. To point out the effect of yellow light on the attempts of such turtles to reach the sea

D. To provide evidence showing that such turtles easily lose their sense of direction

3. According to paragraph 2, which of the following is true of turtle hatchlings that are trying to make their way to the sea?

A. They are unable to distinguish the light of the rising Sun from other types of light.

B. They require the presence of yellow light in order to reach the water’s edge.

C. They have trouble crossing downward slopes near the water’s edge.

D. They respond to light only when it is close to the horizon.

It is usually safest to have more than one internal compass, and hatchlings seem to be guided by more than light alone. They steer away from sand dunes and vegetation. Possibly these objects merely block light behind them that might mislead turtle hatchlings about where the sea is, but it is also possible that turtles are sensitive to the shape of such objects and process these shapes as signals that the sea is located in some other direction. Such reinforcing cues, however, are not enough to guide hatchlings away from the artificial lights that now burn on many a beach environment. Artificial lighting is often strong enough to completely overcome the signals a hatchling sea turtle is programmed to recognize. Artificial light, if it is bright enough, becomes a stimulus so powerful that the hatchlings respond to nothing else, crawling toward it from hundreds of meters away.

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