2018年10月13日托福阅读真题+题目+答案：The Distribution of Gliding Animals
Generally, gliding is used for some animal species as a mean of fleeing from the predators since it enables them to move between trees without the need to descend to the ground and it also is an energy-efficient way to travel long distances between scattered food resources. For scientist, gliding animals (flying squirrels, flying frogs, and flying lizards with wings of skin that allow them to glide through the tropical forest) have long been the intriguing subject of study. Recently, researchers have found that Southeast Asia has a unique abundance and diversity of these animals. This observation leads them to the following questions. What could be an explanation about biological diversity of these animals found in the forest of Southeast Asia and what could explain the scarcity of gliding animals in other regions? Most of all, what makes Southeast Asian rain forests unusual?
Several theories have been proposed by many scientists to explain the diversity of gliding animals in Southeast Asia. The first theory might be called the tall-trees hypothesis. According to this theory, taller trees in Southeast Asia could offer longer glides as well as the opportunity to boost in a dive before gliding because the forests of this region are taller than any other forests in the world, which comes from the domination of dipterocarp family, a family of tall, tropical hardwood trees. And by providing a more advantageous situation for gliding between tall-trees, the lower wind speeds might also contribute to the great number of appearance of gliding animals. This speculation, however, has several flaws. First, gliding animals are found throughout the Southeast Asian region, even in relatively short-stature forests located in the northern area of the rain forest in China, Thailand and Vietnam. Also, some gliders thrive in low secondary forests, plantations, and even city parks. It is obvious that gliding animals do not need tall trees for their activities. In addition, many gliding animals initiate their glides from the middle of tree trunks, not necessarily ascending to the tops of trees to take off.
Another theory, known as broken-forest hypothesis, speculates that animals in Southeast Asia must risk descending to the ground or glide to move between trees because the top layer of the forest-the tree canopy-has fewer woody vines connecting tree crowns in Southeast Asian forests than in New World and African forests. It also presumes that the tree canopy in Asian forests is more uneven in height, due to the existence of tall dipterocarp trees with lower trees between them, and this imbalance is favored by gliding animals. But it is observed by ecologist working in different regions of world that, depending on the site conditions of soil, climate, slope elevation, and local disturbance, there is a tremendous local variation in tree height, canopy structure, and abundance of vines. Indeed, we can find many locations with abundant woody vines and numerous connections between trees in Southeast Asia and similarly many Amazonian forests with few woody vines.
A last theory differs from the others in suggesting that it is the presence of dipterocarp trees themselves that is promoting the evolution of gliding species. ■ According to this theory, dipterocarp forests can be "food-deserts" for the animals that live in them. _ The animals living in dipterocarp forests that have developed gliding divide into two main groups: leaf eaters and carnivores that eat small prey such as insects and small vertebrates. _ For leaf-eating gliders the problems is not the absence of any leaves but the desert-like absence of edible leaves. Dipterocarp trees often account for 50 percent or more of the total number of canopy trees in a forest and over 95 percent of the large trees, yet dipterocarp leaves are unavailable to most vertebrate plant eaters because of the high concentration of toxic chemicals in their leaves. ■ Many species of gliding animals avoid eating dipterocarp leaves and so must travel widely through the forest, bypassing the dipterocarp tree, to find the leaves they need to eat. And gliding is a more efficient way of traveling between trees than descending to the ground and walking or else jumping between trees.
Since there is the lower abundance of prey and other insects, many carnivorous animals also may need to forage more widely for food. This scarcity of food source is caused by dipterocarps’ irregular flowering and fruiting cycles of two- to seven-year intervals, resulting in a shortage of the flowers, fruits, seeds, and seedlings that are the starting point of so many food chains. The lower abundance of prey in dipterocarp forests forces animals such as lizards and geckos to move between tree crowns in search of food, with gliding being the most efficient means.
1 • The word scattered in paragraph 1 is closest in meaning to
(A) seasonally available
(B) hard to find
(C) highly varied
(D) widely separated
2. According to paragraph 1, why is the ability to glide considered useful to forest-dwelling species?
(A) Because gliding removes the need to travel long distances in search of food.
(B) Because gliding serves as a rapid, energy efficient way of descending from trees.
(C) Because gliding gives them an advantage of moving through the forest without being exposes to predators in the ground.
(D) Because gliding makes them possible to adapt to various forests conditions.
3. According to paragraph 1, researchers are trying to answer which of the following question about gliding species
(A) Why gliding animals, which are uncommon in most tropical forests, have developed in so many different families in Southeast Asia.
(B) Why gliding animals developed in many tropical forests in Southeast Asia before they evolved in other tropical forests in the world.
(C) Why gliding animals limitedly evolved in tropical rain forests.
(D) Why gliding animals evolved so slowly in the tropical forests of Southeast Asia.
4. According to paragraph 2, which of the following does NOT support the tall-trees hypothesis
(A) tall trees let longer glides possible.
(B) gliding from the middle of tree trunks can be possible because trees are tall.
(C) tall trees make increased speed in a dive possible.
(D) there is lower wind speeds between tall trees.,
5. Select the TWO answer choices that point to flaws in the tall-trees hypothesis, according to paragraph 2. To receive credit,you must select TWO answers.
(A) Many gliding animals begin their glides from midway positions of tree trunks.
(B) Gliding animals are not evenly spread throughout the forests of the Southeast Asian region.
(C) Most gliding animals are incapable of ascending to the tops of trees.
(D) Many gliding animals are found in locations where trees tend to be relatively short.
6. The word speculates in paragraph 3 is closest in meaning to
(B) puts forward as a possibility
(D) concludes from evidence
7. Paragraph 3 suggests which of the following ideas about forests in which there are abundant woody vines connecting tree crowns?
(A) There are likely fewer predators on the ground in such forests than in other forests.
(B) In such forest, the tree canopy is more even than that in other forests.
(C) In such forest, there is a wider diversity of animals than other forests.
(D) Animals in such forests can move between trees by traveling on vines.
8. The word tremendous in paragraph 3 is closest in meaning to
9. Paragraph 3 supports the idea that one problem with the broken-forest hypothesis is that
(A) in broken forests with an uneven canopy structure, gliding is difficult, and it is easy in forests where the trees are all about the same height
(B) ecologists in different region have found that gliding animals are as abundant and varied in some forests of Africa and the New World as they are in Southeast Asian forests
(C) ecologists have found gliding animals in areas of Southeast Asia where trees are connected by vines and not found them in Amazonian forests where trees are not connected by vines
(D) with the fewest woody vines connecting the tops of trees, the forest in Southeast Asia turn out to have the most gliding animals
10. According to paragraph 4, what difficulty do leaf-eating animals have in a dipterocarp forest?
(A) There is no efficient method of obtaining from one tree to another.
(B) There is a large gap between trees that have edible leaves.
(C) Leaves of most trees locates very high tree trunk so it makes animals difficult to reach.
(D) Dipterocarp trees have less leaves than those of other canopy trees.
11. How does paragraph 5 related to paragraph 4?
(A) Paragraph 5 finishes the explanation of the food-desert theory initiated in paragraph 4.
(B) Paragraph 5 explains why the author calls the theory set out in paragraph 4 the food-desert theory.
(C) Paragraph 5 suggests an alternative to the food-desert theory described in paragraph 4.
(D) Paragraph 5 mentions the limitations of the food-desert theory introduced in paragraph 4.
12. According to paragraph 5, what is responsible for the relative scarcity insects and other prey in dipterocarp forests?
(A) The proficient hunting method of lizards and geckos
(B) A plethora of carnivorous animals in dipterocarp forests
(C) The unusual behavior of insects and other prey to eat the toxic seeds, flowers, and fruits of dipterocarp trees
(D) Irregular flowering and fruiting cycles of Dipterocarps trees
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
For each group, a dipterocarp forest is like a desert in that food resources are few and far apart.
Where would the sentence best fit?
14. Summary Various theories have been suggested to explain the unique abundance and diversity of gliding animals in the rain forests of Southeast Asia.
(A) The fact that the abundance of gliding animals in different regions of the world corresponds to difference in tree height,canopy structure and amount of vines has been explained by ecologists.
(B) One theory suggests that so many gliding species evolved in Southeast Asia because the forests are exceptionally tall,but there is evidence that the theory is not enough.
(C) Jumping from tree to tree or descending to the ground and walking in forests that are dominated by tall trees may be a more energy-efficient way of traveling through the forest than gliding.
(D) The fact that gliding animals are most abundant in the short-structure forests of Southeast region indicates that gliding did not evolve as an adaptation to an environment of tall trees.
(E) Dipterocarp trees create an environment in which many species must travel widely to find food, and gliding may have evolved as a rapid and efficient way of moving between tree crowns.
(F) The hypothesis that gliding evolved to compensate for a scarcity of vines linking tree canopies overlooks problematic evidence from both Southeast Asian and Amazonian forests.