Official17 托福阅读Passage2Animal Signal in the Rain Forest文本+题目原文+答案解析【雷哥托福】2019-01-29 11:20:53 发布 来源：雷哥托福 阅读量:3731
TPO17 托福阅读Passage2Animal Signal in the Rain Forest文本+题目原文+答案解析
Animal Signal in the Rain Forest
The daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in these various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite conspicuous in another.
In the varied and constantly changing light environment of the forest, an animal must be able to send visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themselves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can change from a rather dull appearance to a full riot of carnival colors in seconds. By this means, they signal their level of aggression or readiness to mate.
Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradise may put himself in the limelight by displaying his spectacular plumage in the best stage setting to attract a female. Certain butterflies move into spots of sunlight that have penetrated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights. They also compete with each other for the best spot of sunlight.
Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelengths predominate. A signal might be most easily seen if it is maximally bright. In the green-to-yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, these colors would not be very visible if the animal was sitting in an area with a yellowish or greenish background. The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen. In this part of the rain forest, therefore, red and orange are the best colors for signaling, and they are the colors used in signals by the ground-walking Australian brush turkey. This species, which lives in the rain forests and scrublands of the east coast of Australia, has a brown-to-black plumage with bare, bright-red skin on the head and neck and a neck collar of orange-yellow loosely hanging skin. During courtship and aggressive displays, the turkey enlarges its colored neck collar by inflating sacs in the neck region and then flings about a pendulous part of the colored signaling apparatus as it utters calls designed to attract or repel. This impressive display is clearly visible in the light spectrum illuminating the forest floor.
Less colorful birds and animals that inhabit the rain forest tend to rely on forms of signaling other than the visual, particularly over long distances. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. The male riflebird exploits both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.
Less colorful birds and animals that inhabit the rain forest tend to rely on forms of signaling other than the visual, particularly over long distances.
■ The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. ■In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. ■In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. ■The male riflebird exploits both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.
TPO17托福阅读Passage2 Animal Signal in the Rain Forest 题目
Question 1 of 14: The phrase “conspicuous” in the passage is closest in meaning to
Question 2 of 14: According to paragraph 2 what is problematic about an animal’s sending visual signals to members of its own species?
A. signs that make an animal visible to its species also make it visible to predators
B. an animal that changes color to avoid predators can confuse members of its species
C. changing light may require an animal to move beyond the visual range of other members
D. the animal may mistakenly signal aggression when it meant to signal readiness to mate.
Question 3 of 14: The word “signal” in the passage is closest in meaning to
Question 4 of 14: According to paragraph 2 all of the following are reasons amphibians and reptiles change color EXCEPT
A. changing seasons
B. to signal others of their species
C. to match the light
D. to hide from predators
Question 5 of 14: According to paragraph 3, butterflies move into spots of sunlight in order to
A. warm their wings in order to open them
B. compete with each other
C. take advantage of favorable light conditions on the forest floor
D. imitate birds of paradise
Question 6 of 14: According to paragraph 4, what is true about light that reaches ground level?
A. It reveals only the yellow and green colors animals use to signal each other.
B. It reflects the yellow and green colors to make the floor as bright as sunshine
C. It camouflages animals whose natural colors are yellow and green
D. It consists mostly of yellow-to-green wavelengths
Question 7 of 14: 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.
A. When an animal is signaling in an area with green-to-yellow lighting conditions, its signal will not be visible if the background is brightly lit
B. In the lowest levels of the forest, an animal’s signals are not easily seen unless there is a yellowish or greenish background
C. In the green-to-yellow lighting conditions at the lowest levels of the forest, only signals that are themselves green or yellow will be bright enough to be seen in most areas.
D. Although green and yellow would be the brightest colors near the forest floor, these colors would make poor signals whenever the forest background was also in the green-to-yellow range
Question 8 of 14: The word “inflating” in the passage is closest in meaning to
Question 9 of 14: Which of the following can be inferred from paragraph 4 about yellow and green colors compared with red and orange colors at the bottom of the forest?
A. Yellow and green are better colors for signaling than red and orange colors.
B. Orange and red are brighter colors than yellow and green.
C. Yellow and green are likely to be more common in the background than red and orange
D. Orange and red colors do not contrast as well with the forest floor as yellow and green do
Question 10 of 14: What can be inferred from paragraph 5 about the less colorful birds and animals that inhabit the forest?
A. These species are less able to see color, and therefore they communicate with one another using nonvisual signals.
B. These species generally live in less densely wooded environments than more colorful birds and animals do.
C. The cries of these species do not carry as well over distances as the cries of more colorful birds and animals.
D. These species depend more on nonvisual signals for communication because they are less visible in their environment
Question 11 of 14: The word “impediment” in the passage is closest in meaning to
Question 12 of 14: The word “exploits” in the passage is closest in meaning to
B. makes use of
C. increases the intensity of
Question 13 of 14: Look at the four squares ■ that indicate where the following sentence could be added to the passage.
There is also the long, rather terrifying call of the male orangutan, which carries over considerable distances to advertise his presence.
Where would the sentence best fit?
A. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons.
B. In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation.
C. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees.
D.The male riflebird exploits both of these modes of signaling simultaneously in his courtship display.
Question 13 of 14: In the rain forest, an animal must be able to send signals to members of its own species and at the same time avoid being detected by predators.
A. Animals that have different predators at different times of day change color to avoid being detected
B. To be noticed, an animal may draw attention to the contrast between its colors and the colors of its environment.
C. Yellow and green are the most common colors found in the rainforest.
D. To escape notice an animal may move or change color so that its color pattern is not visible
E. Animals must have signals for aggression as well as to indicate readiness to mate
F. An animal may use sound rather than color to attract attention, because sound signals are not hindered by light conditions.
TPO17托福阅读Passage2Animal Signal in the Rain Forest真题解析
Question 1 of 14
Question 2 of 14
解析：以members of its own species做关键词定位至第二段第一句，说动物给自己的同类发信号的时候必须同时避免被天敌看到，所以答案是A，动物的信号也会被捕食者看到。B的confuse members，C的beyond the visual range和D的mistakenly signal aggression原文都未提及。
Question 3 of 14
Question 4 of 14
解析：EXCEPT题，A在原文没有对应点，所以A错，选；B的signal others做关键词定位至第二段倒数第三句，正确，不选；C的light做关键词定位至第一句，说根据不同的光线环境不断改变自己的颜色，所以C正确，不选；D的hide from predators做关键词定位至倒数第四句，说camouflage themselves，所以D正确，不选。
Question 5 of 14
解析：根据关键词spots of sunlight定位到第三段最后两句：某些蝴蝶飞到落在森林地面的太阳光点处，在明亮的光点中扇动着带有美丽图案的翅膀来展现自己。它们还会互相争夺最佳的光照位置。对应C选项，运用森林地表良好的光线条件。AD没有提到，B错在竞争是手段，不是目的，而题干问的是目的。
Question 6 of 14
解析：根据关键词light that reaches ground定位到第一句后半句：at those level the yellow-to-green wavelengths predominate。到达森林地表的光中，黄绿色光最多。对应D选项。
Question 7 of 14
Question 8 of 14
Question 9 of 14
解析：以red and orange colours做关键词定位至第四句和五句，提到最好的信号不仅要亮，而且要与背景对比鲜明，在靠近森林地表处，红色和橙色是最好的信号色。说明比起红色和橙色，黄色和绿色与森林地表的背景色更接近，对应C选项。
Question 10 of 14
解析：以less colourful birds and animals做关键词定位至第一句，原句提到这些动物会更多依靠非视觉的信号来交流，答案是D。B和C未提及，另外A错在原文说的是这个鸟本身less colourful，而不是less able to see colour，这里偷换了概念。
Question 11 of 14
Question 12 of 14
解析：exploit“开采，开发，剥削，利用”，所以B make use of正确。原文提到在雄性风鸟在求爱的时候会同时_____声音和视觉两种方式。能推出是利用的意思。所以选B。
Question 13 of 14
解析：通过副词also和句中出现的名词call可以推出前面也出现了与call意思类似的词，所以选B，B前面一句出现了the piercing cries与插入句中的the long, rather terrifying call相对应。
Question 14 of 14
A错在原文没有提到have different predators at different times，原文第二段第三句提到的是：为了躲避天敌，动物要选择最不突出它们存在的光线环境，所以要在一天不同的时间去不同的地方。A偷换了概念，所以错误。第四段第一句提到黄色绿色是靠近森林地表最常见的颜色，而不是整个雨林，所以C错误；E在原文中没有提到，原文第二段最后一句只是说它们通过这种方式来发送侵略或者求爱的信号，并没有提到分别有不同的方式来进行这两个行为。