托福阅读真题第184篇Plant and Animal Life of the Pacific Islands
Plant and Animal Life of the Pacific Islands
Paragraph 1: There are both great similarities and considerable diversity in the ecosystems that evolved on the islands of Oceania in and around the Pacific Ocean. The islands, such as New Zealand, that were originally parts of continents still carry some small plant and animal remnants of their earlier biota (animal and plant life), and they also have been extensively modified by evolution, adaptation, and the arrival of new species. By contrast, the other islands, which emerged via geological processes such as volcanism, possessed no terrestrial life, but over long periods, winds, ocean currents, and the feet, feathers, and digestive tracts of birds brought the seeds of plants and a few species of animals. Only those species with ways of spreading to these islands were able to undertake the long journeys, and the various factors at play resulted in diverse combinations of new colonists on the islands. One estimate is that the distribution of plants was 75 percent by birds, 23 percent by floating, and 2 percent by wind.
1. The passage supports which of the following statements about species on volcanic islands?
O Volcanic island species are unlike the species found in other Pacific Ocean locations.
O Volcanic islands lack the diversity of species found elsewhere in the Pacific.
O Volcanic island species are all transplants from distant locations and exist in combinations not found elsewhere.
O Volcanic island species differ from those on other islands in that animal species have greater diversity than plant species do.
2. According to paragraph 1, how did the majority of plant species arrive on islands created by geological processes such as volcanism?
O They were transported by ocean currents.
O They were carried to the islands by birds.
O They were brought to the islands by humans.
O They were transported by winds.
Paragraph 2: The migration of Oceanic biota was generally from west to east, with four major factors influencing their distribution and establishment. The first was the size and fertility of the islands on which they landed, with larger islands able to provide hospitality for a wider range of species. Second, the further east the islands, generally the less the species diversity, largely because of the distance that had to be crossed and because the eastern islands tended to be smaller, more scattered, and remote. This easterly decline in species diversity is well demonstrated by birds and coral fish. It is estimated that there were over 550 species of birds in New Guinea, 127 in the Solomon Islands, 54 in Fiji, and 17 in the Society Islands. From the west across the Pacific, the Bismarck Archipelago and the Solomon Islands have more than 90 families of shore fish (with many species within the families), Fiji has 50 families, and the Society Islands have 30. Third, the latitude of the islands also influenced the biotic mix, as those islands in relatively cooler latitudes, notably New Zealand, were unsuited to supporting some of the tropical plants with which Pacific islands are generally associated.
3. In paragraph 2, what is the author’s purpose in mentioning the estimated numbers of birds and coral fish species on various Oceanic islands?
O To give examples of the wide range of species that can be found on Oceanic islands
O To demonstrate how much knowledge about Oceanic species has been accumulated
O To illustrate the decline in species diversity from west to east on Oceanic islands
O To identify the influence of latitude upon Oceanic plants and animals
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 Because of its latitude, New Zealand had a relatively cooler climate than other Pacific islands.
O New Zealand, like other Pacific islands, showed the effects of latitudes on its rich tropical plants.
O Because the latitudinal position of an island also affected its biotic mix, islands in cooler latitudes did not support some tropical species typical of the Pacific islands.
O Pacific islands were notable for their impressive biotic mix and association with tropical plants.
Paragraph 3: Finally, a fourth major factor in species distribution, and indeed in the shaping of Pacific ecosystems, was wind. It takes little experience on Pacific islands to be aware that there are prevailing winds. To the north of the equator these are called north-easterlies, while to the south they are called south-easterlies. Further south, from about 30°south, the winds are generally from the west. As a result on nearly every island of significant size there is an ecological difference between its windward and leeward (away from the wind) sides. Apart from the wind action itself on plants and soils, wind has a major effect on rain distribution. The Big Island of Hawaii offers a prime example; one can leave Kona on the leeward side in brilliant sunshine and drive across to the windward side where the city of Hilo is blanketed in mist and rain.
5. The Big Island of Hawaii is discussed in the passage as an example of
O the relationship between latitude and wind
O how prevailing winds influence rainfall patterns
O the relationship between rainfall and species distribution
O the effects of wind action upon plants and soils
6 What can be inferred from paragraph 3 about Kona and Hilo?
O The ecosystems of Kona and Hilo differ from each other.
O Kona and Hilo have approximately the same rainfall in a given year.
O Kona receives northeasterly winds while Hilo receives southeasterly winds.
O Both Kona and Hilo have plants and soils that are often damaged by winds.
Paragraph 4: While such localized plant life and climatic conditions are very noticeable, over Oceania as a whole there is relatively little biodiversity, and the smaller the island and the further east it lies, the less there is likely to be. When humans moved beyond the islands of Near Oceania (Australia, New Guinea, and the Solomon Islands), they encountered no indigenous mammals except for flying foxes, fruit bats, and seals on some islands. Other vertebrate species were restricted to flying animals and a few small reptiles. However, local adaptations and evolution over long periods of isolation promoted fascinating species adaptations to local conditions. Perhaps most notable, in the absence of mammals and other predators, are the many species of flightless and ground-nesting birds. Another consequence of evolution was that many small environments boasted their own endemic (native) species, often small in number, unused to serious predation, limited in range, and therefore vulnerable to disruption. In Hawaii, for example, the highly adapted 39 species and subspecies of honeycreepers, several hundred species of fruit flies, and more than 750 species of tree snails are often cited to epitomize the extent of localized Oceanic endemism (species being native to the area).
7. According to paragraph 4, why have species of flightless and ground-nesting birds become so numerous on Oceanic islands?
O They have no predators on the islands.
O They were some of the strongest species to arrive on the islands.
O They live closer to their food sources than other species do.
O They are affected less by climatic changes than other animals are.
8. Which of the following is NOT mentioned in paragraph 4 about the species that live on Oceanic islands?
O Certain species are native only to particular islands.
O Species that are native to Oceanic islands include relatively few mammals.
O Populations of most species are small in number.
O Some species have evolved over time to become predators.
Paragraph 1: There are both great similarities and considerable diversity in the ecosystems that evolved on the islands of Oceania in and around the Pacific Ocean. ■The islands, such as New Zealand, that were originally parts of continents still carry some small plant and animal remnants of their earlier biota (animal and plant life), and they also have been extensively modified by evolution, adaptation, and the arrival of new species. ■By contrast, the other islands, which emerged via geological processes such as volcanism, possessed no terrestrial life, but over long periods, winds, ocean currents, and the feet, feathers, and digestive tracts of birds brought the seeds of plants and a few species of animals. ■Only those species with ways of spreading to these islands were able to undertake the long journeys, and the various factors at play resulted in diverse combinations of new colonists on the islands. ■One estimate is that the distribution of plants was 75 percent by birds, 23 percent by floating, and 2 percent by wind.
9. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
When varied ecosystems are present, they can be explained as resulting in part from the process that formed the islands.
Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.
10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your choices to the spaces where they belong. To review the passage, click on View Text.
Biodiversity on Oceanic islands is dependent on a number of factors.
Answer Choices
O Unlike Oceanic islands that were once part of continental landmasses, islands formed by such geological processes as volcanism contain only plants and animals that could be transported there.
O An island’s size is less important than its latitude in determining species diversity.
O Though biodiversity is low on many Oceanic islands, many native species have evolved that are uniquely adapted to their local environments.
O Species distribution in Oceania is determined by the location of islands, their size, and the direction of the wind.
O Most Oceanic islands are similar to one another in latitude and contain plants and animals typical of tropical islands.
O The absence of natural predators on the eastern Oceanic islands allowed many species of large mammals to evolve that were capable of inhabiting a wide range of territory.
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