1、托福（阅读）模拟试卷 7及答案与解析 一、 Sections Three： Reading Comprehension 0 “Symbiotic Relationships“ Symbiosis is a close, long-lasting physical relationship between two different species. In other words, the two species are usually in physical contact and at least one of them derives some sort of benefit from t
2、his contact. There are three different categories of symbiotic relationships: parasitism, commensal-ism, and mutualism. Parasitism is a relationship in which one organism, known as the parasite, lives in or on another organism, known as the host, from which it derives nourishment. Generally, the par
3、asite is much smaller than the host. Although the host is harmed by the interaction, it is generally not killed immediately by the parasite, and some host individuals may live a long time and be relatively little affected by their parasites. Some parasites are much more destructive than others, howe
4、ver.Newly established parasite-host relationships are likely to be more destructive than those that have a long evolutionary history. With a longstanding interaction between the parasite and the host, the two species generally evolve in such a way that they can accommodate one another. It is not in
5、the parasites best interest to kill its host. If it does, it must find another. Likewise, the host evolves defenses against the parasite, often reducing the harm done by the parasite to a level the host can tolerate. Parasites that live on the surface of their hosts are known as ectoparasites. Fleas
6、, lice, and some molds and mildews are examples of ectoparasites. A Many other parasites, such as tapeworms, malaria parasites, many kinds of bacteria, and some fungi, are called endoparasites because they live inside the bodies of their hosts. B A tapeworm lives in the intestines of its host where
7、it is able to resist being digested and makes use of the nutrients in the intestine. C Even plants can be parasites. Mistletoe is a flowering plant that is parasitic on trees. It establishes itself on the surface of a tree when a bird transfers the seed to the tree. It then grows down into the water
8、-conducting tissues of the tree and uses the water and minerals it obtains from these tissues to support its own growth. D Commensalism is a relationship between organisms in which one organism benefits while the other is not affected. It is possible to visualize a parasitic relationship evolving in
9、to a commensal one. Since parasites generally evolve to do as little harm to their host as possible and the host is combating the negative effects of the parasite, they might eventually evolve to the point where the host is not harmed at all. Many examples of commensal relationships exist. Many orch
10、ids use trees as a surface upon which to grow. The tree is not harmed or helped, but the orchid needs a surface upon which to establish itself and also benefits by being close to the top of the tree, where it can get more sunlight and rain. Some mosses, ferns, and many vines also make use of the sur
11、faces of trees in this way. In the ocean, many sharks have a smaller fish known as a remora attached to them. Remoras have a sucker on the top of their heads that they can use to attach to the shark. In this way, they can hitchhike a ride as the shark swims along. When the shark feeds, the remora fr
12、ees itself and obtains small bits of food that the shark misses. Then, the remora reattaches. The shark does not appear to be positively or negatively affected by remoras. Mutualism is another kind of symbiotic relationship and is actually beneficial to both species involved. In many mutualistic rel
13、ationships, the relationship is obligatory; the species cannot live without each other. In others, the species can exist separately but are more successful when they are involved in a mutualistic relationship. Some species of Acacia, a thorny tree, provide food in the form of sugar solutions in litt
14、le structures on their stems. Certain species of ants feed on the solutions and live in the tree, which they will protect from other animals by attacking any animal that begins to feed on the tree. Both organisms benefit; the ants receive food and a place to live, and the tree is protected from anim
15、als that would use it as food. One soil nutrient that is usually a limiting factor for plant growth is nitrogen. Many kinds of plants, such as legumes, beans, clover, Acacia trees, and Alder trees, have bacteria that live in their roots in little nodules. The roots form these nodules when they are i
16、nfected with certain kinds of bacteria. The bacteria do not cause disease but provide the plants with nitrogen-containing molecules that the plants can use for growth. The nitrogen-fixing bacteria benefit from the living site and nutrients that the plants provide, and the plants benefit from the nit
17、rogen they receive. Glossary sucker: an adaptation for sucking nourishment or sticking to a surface nodules: growths in the form of knots 1 The word derives in the passage is closest in meaning to （ A） requests （ B） pursues （ C） obtains （ D） rejects 2 The word it in the passage refers to （ A） host （
18、 B） organism （ C） parasite （ D） relationship 3 The word relatively in the passage is closest in meaning to （ A） comparatively （ B） routinely （ C） adversely （ D） frequently 4 Which of the sentences below best expresses the information in the highlighted statement in the passage? The other choices cha
19、nge the meaning or leave out important information. （ A） A parasite is less likely to destroy the host when it attaches itself at first. （ B） Parasites that have lived on a host for a long time have probably done a lot of damage. （ C） The most destructive phase for a host is when the parasite first
20、invades it. （ D） The relationship between a parasite and a host will evolve over time. 5 The word tolerate in the passage is closest in meaning to （ A） permit （ B） oppose （ C） profit （ D） avoid 6 According to paragraph 3, how do ectoparasites survive? （ A） They live in mold and mildew on their hosts
21、. （ B） They digest food in the intestines of their hosts. （ C） They live on the nutrients in their bacterial hosts. （ D） They inhabit the outside parts of their hosts. 7 Which of the following is mentioned as an example of a commensal relationship? （ A） Orchids （ B） Mistletoe （ C） Ants （ D） Fungus 8
22、 The word actually in the passage is closest in meaning to （ A） frequently （ B） initially （ C） really （ D） usually 9 In paragraph 8, why does the author use the example of the Acacia tree? （ A） To demonstrate how ants survive by living in trees （ B） To explain how two species can benefit from contac
23、t （ C） To show the relationship between plants and animals （ D） To present a problem that occurs often in nature 10 According to paragraph 9, how does bacteria affect beans and clover? （ A） It causes many of the plants to die. （ B） It limits the growth of young plants. （ C） It supplies nitrogen to t
24、he crops. （ D） It infects the roots with harmful nodules. 11 Look at the four squares that show where the following sentence could be inserted in the passage. They live on the feathers of birds or the fur of animals. Where could the sentence best be added? Click on a square to insert the sentence in
25、 the passage. 12 In which of the following chapters would this passage most probably appear? （ A） Environment and Organisms （ B） Pollution and Policies （ C） Human Influences on Ecosystems （ D） Energy Resources 13 An introduction for a short summary of the passage appears below. Complete the summary
26、by selecting the THREE answer choices that mention the most important points in the passage. Some sentences do not belong in the summary because they express ideas that are not included in the passage or are minor points from the passage. This question is worth 2 points. Symbiosis is a close, contin
27、uing physical relationship between two species. - - - Answer Choices A Parasitic species will feed on the host species, causing varying degrees of damage to the host as a result of the relationship. B Orchids benefit from being near the top of a tree where they can be exposed to more sunlight and ra
28、in. C Nodules in the roots of plants supply nitrogen from bacteria, thereby enriching the soil. D In commensalism, one species will benefit from the relationship, but the other species is not affected by it. E Certain species form mutualistic relationships in which both species benefit from the phys
29、ical contact. F Evolutionary changes in species may allow them to live in close physical contact with little damage to each other. 13 “Civilization“ Between 4000 and 3000 B.C., significant technological developments began to transform the Neolithic towns. The invention of writing enabled records to
30、be kept, and the use of metals marked a new level of human control over the environment and its resources. Already before 4000 B.C., craftspeople had discovered that metal-bearing rocks could be heated to liquefy metals, which could then be cast in molds to produce tools and weapons that were more u
31、seful than stone instruments. Although copper was the first metal to be utilized in producing tools, after 4000 b.c. craftspeople in western Asia discovered that a combination of copper and tin produced bronze, a much harder and more durable metal than copper. Its widespread use has led historians t
32、o call the period the Bronze Age; thereafter, from around 3000 to 1200 b.c, bronze was increasingly replaced by iron. At first, Neolithic settlements were hardly more than villages. But as their inhabitants mastered the art of farming, more complex human societies emerged. As wealth increased, these
33、 societies began to develop armies and to build walled cities. By the beginning of the Bronze Age, the concentration of larger numbers of people in the river valleys of Southwest Asia and Egypt was leading to a whole new pattern for human life. As we have seen, early human beings formed small groups
34、 that developed a simple culture that enabled them to survive. As human societies grew and developed greater complexity, a new form of human existence called civilization came into being. A civilization is a complex culture in which large numbers of human beings share a number of common elements. Hi
35、storians have identified a number of basic characteristics of civilization, most of which are evident in the Southwest Asian and Egyptian civilizations. These include (1) an urban focus: cities became the centers of political, economic, social, cultural, and religious development; (2) a distinct rel
36、igious structure: the gods were deemed crucial to the communitys success, and professional priestly classes, as stewards of the gods property, regulated relations with the gods; (3) new political and military structures: an organized government bureaucracy arose to meet the administrative demands of
37、 the growing population while armies were organized to gain land and power and for defense; (4) a new social structure based on economic power: while kings and an upper class of priests, political leaders, and warriors dominated, there also existed large groups of free people (farmers, artisans, cra
38、ftspeople) and at the very bottom, socially, a class of slaves; (5) the development of writing: kings, priests, merchants, and artisans used writing to keep records; and (6) new forms of significant artistic and intellectual activity: monumental architectural structures, usually religious, occupied
39、a prominent place in urban environments. Why early civilizations developed remains difficult to explain. A Since civilizations developed independently in India, China, Mesopotamia, and Egypt, can general causes be identified that would explain why all of these civilizations emerged? B A number of po
40、ssible explanations of the beginning of civilization have been suggested. A theory of challenge and response maintains that challenges forced human beings to make efforts that resulted in the rise of civilization. Some scholars have adhered to a material explanation. C Material forces, such as the g
41、rowth of food surpluses, made possible the specialization of labor and development of large communities with bureaucratic organization. D But the area of the Fertile Crescent, in which civilization emerged in Southwest Asia, was not naturally conducive to agriculture. Abundant food could be produced
42、 only with a massive human effort to carefully manage the water, an effort that created the need for organization and bureaucratic control and led to civilized cities. Some historians have argued that nonmaterial forces, primarily religious, provided the sense of unity and purpose that made such org
43、anized activities possible. Finally, some scholars doubt that we are capable of ever discovering the actual causes of early civilization. 14 Which of the following is the best definition of a “civilization“? （ A） Neolithic towns and cities （ B） Types of complex cultures （ C） An agricultural communit
44、y （ D） Large population centers 15 The word its in the passage refers to （ A） copper （ B） bronze （ C） metal （ D） iron 16 According to paragraph 2, what happens as societies become more prosperous? （ A） More goods are produced. （ B） Walled cities are built. （ C） Laws are instituted. （ D） The size of
45、families increased. 17 The word hardly in the passage is closest in meaning to （ A） frequently （ B） likely （ C） barely （ D） obviously 18 Why does the author mention “Neolithic settlements“ in paragraph 2? （ A） To give an example of a civilization （ B） To explain the invention of writing systems （ C）
46、 To argue that they should be classified as villages （ D） To contrast them with the civilizations that evolved 19 According to paragraph 3, how was the class system structured? （ A） An upper class and a lower class （ B） Slaves, free people, and a ruling class （ C） A king, an army, and slaves （ D） In
47、tellectuals and uneducated farmers and workers 20 Which of the sentences below best expresses the information in the highlighted statement in the passage? The other choices change the meaning or leave out important information. （ A） Southwest Asian and Egyptian civilizations exhibit the majority of
48、the characteristics identified by historians. （ B） The characteristics that historians have identified are not found in the Egyptian and Southwest Asian cultures. （ C） Civilizations in Southwest Asia and Egypt were identified by historians who were studying the characteristics of early cultures. （ D
49、） The identification of most historical civilizations includes either Egypt or Southwest Asia on the list. 21 The word crucial in the passage is closest in meaning to （ A） fundamental （ B） arbitrary （ C） disruptive （ D） suitable 22 The word prominent in the passage is closest in meaning to （ A） weak （ B） important （ C） small （ D） new 23 According to paragraph 4, how can the independent development of civilization in different geographic regions be explained? （ A） Scholars agree that food surpluses encouraged populations to be concentrated in certain areas. （ B） There are sev
