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托福阅读TPO31真题原文及答案

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托福阅读TPO31真题Part1原文及答案

Plant Colonization

Colonization is one way in which plants can change the ecology of a site. Colonization is a process with two components: invasion and survival. The rate at which a site is colonized by plants depends on both the rate at which individual organisms (seeds, spores, immature or mature individuals) arrive at the site and their success at becoming established and surviving. Success in colonization depends to a great extent on there being a site available for colonization – a safe site where disturbance by fire or by cutting down of trees has either removed competing species or reduced levels of competition and other negative interactions to a level at which the invading species can become established. For a given rate of invasion, colonization of a moist, fertile site is likely to be much more rapid than that of a dry, infertile site because of poor survival on the latter. A fertile, plowed field is rapidly invaded by a large variety of weeds, whereas a neighboring construction site from which the soil has been compacted or removed to expose a coarse, infertile parent material may remain virtually free of vegetation for many months or even years despite receiving the same input of seeds as the plowed field.

Both the rate of invasion and the rate of extinction vary greatly among different plant species. Pioneer species – those that occur only in the earliest stages of colonization – tend to have high rates of invasion because they produce very large numbers of reproductive propagules (seeds, spores, and so on) and because they have an efficient means of dispersal (normally, wind)

If colonizers produce short-lived reproductive propagules, then they must produce very large numbers unless they have an efficient means of dispersal to suitable new habitats. Many plants depend on wind for dispersal and produce abundant quantities of small, relatively short-lived seeds to compensate for the fact that wind is not always a reliable means of reaching the appropriate type of habitat. Alternative strategies have evolved in some plants, such as those that produce fewer but larger seeds that are dispersed to suitable sites by birds or small mammals or those that produce long-lived seeds. Many forest plants seem to exhibit the latter adaptation, and viable seeds of pioneer species can be found in large numbers on some forest floors. For example, as many as 1,125 viable seeds per square meter were found in a 100-year-old Douglas fir/western hemlock forest in coastal British Columbia. Nearly all the seeds that had germinated from this seed bank were from pioneer species. The rapid colonization of such sites after disturbance is undoubtedly in part a reflection of the large seed bank on the forest floor.

An adaptation that is well developed in colonizing species is a high degree of variation in germination (the beginning of a seed’s growth). Seeds of a given species exhibit a wide range of germination dates, increasing the probability that at least some of the seeds will germinate during a period of favorable environmental conditions. This is particularly important for species that colonize an environment where there is no existing vegetation to ameliorate climatic extremes and in which there maybe great climatic diversity.

Species succession in plant communities, i.e., the temporal sequence of appearance and disappearance of species is dependent on events occurring at different stages in the life history of a species. Variation in rates of invasion and growth plays an important role in determining patterns of succession, especially secondary succession. The species that are first to colonize a site are those that produce abundant seed that is distributed successfully to new sites. Such species generally grow rapidly and quickly dominate new sites, excluding other species with lower invasion and growth rates. The first community that occupies a disturbed area therefore may be composed of species with the highest rate of invasion, whereas the community of the subsequent stage may consist of plants with similar survival rates but lower invasion rates.

1. According to paragraph 1, how does disturbance of a site influence its colonization by a plant species?

A) Disturbance reduces or eliminates competition by other species.

B) Disturbance increases negative interactions with other organisms on the site. C) Disturbance prevents a plant species from colonizing a new site.

D) Disturbance reduces the fertility of a site.

2. The word “virtually” in the passage is closest in meaning to

A) almost totally

B) unusually

C) consistently

D) unnaturally

3. Why does the author mention a plowed field and a construction site in the passage?

A) To argue that sites that have been affected by human activity tend to be colonized slowly

B) To illustrate the kind of sites that may be invaded by weeds

C) To contrast sites in terms of their suitability for colonization

D) To explain that exposing or compacting the soil results in successful colonization

4. The word “despite” in the passage is closest in meaning to

A) without

B) almost never

C) even though

D) perhaps

5. 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) The seeds of pioneer species are usually carried by the wind to fertile sites, where they reproduce very efficiently.

B) Pioneer species are successful invaders because they produce lots of seeds that are dispersed effectively.

C) Pioneer species produce their largest numbers of propagules during the earliest stages of their colonization.

D) Pioneer species reproduce very quickly and efficiently because they produce very large number of seeds.

6. What can be inferred from paragraph 3 about the reason that large seeds are dispersed by birds or small animals rather than by wind?

A) Large seeds are easier for birds and animals to see than are the small seeds dispersed by the wind.

B) Large seeds are too heavy for the wind to disperse.

C) Large seeds cannot be eaten by birds and animals.

D) Large seeds are short-lived and thus require a more efficient means of dispersal than small seeds do.

7. The phrase “the latter adaptation” in the passage refers to

A) producing fewer seeds

B) producing larger seeds

C) dispersal by birds and small mammals

D) producing long-lived seeds

8. The word “viable” in the passage is closest in meaning to

A) able to survive

B) individual

C) large

D) remaining

9. The example of the 100-year-old Douglas fir/western hemlock forest in paragraph to illustrates which of the following ideas?

A) It is uncommon for older seed to germinate.

B) Pioneer species tend to prefer forest floors for colonization purposes.

C) Long-lived seeds of pioneer species can successfully germinate over long

periods of time.

D) Coastal British Columbia is particularly suited for pioneer species to develop.

10. According to paragraph 4, how do plants manage to germinate in areas with great climatic diversity and climatic extremes?

A) By producing seeds only during favorable climatic conditions

B) By generating large numbers of seeds

C) By colonizing only those areas where other plants have survived

D) By producing seeds that have a wide range of germination dates

11. The word “abundant” in the passage is closest in meaning to

A) new

B) improved

C) suitable

D) plentiful

12. According to paragraph 5, which of the following determines the sequence in which plant species will colonize a site?

A) The extent of growth of a species on a prior site before it begins to colonize a secondary site

B) The differences in invasion and growth rates across species

C) The degree of fertility of a site

D) The kind of disturbance that the site has undergone

13. Look at the four squares [ ] that indicate where the following sentence could be added to the passage.

They require relatively little protection or nutrients.

Where does the sentence best fit?

14. Prose Summary

The ecology of a site is changed through its colonization by new plants that arrive and grow there.

Answer Choices:

A) The species that first colonize a disturbed site are typically ones that produce a large number of efficiently dispersed seeds.

B) Plants that cannot successfully compete with other species can invade and colonize a site only if it is fertile and moist, such as a plowed field.

C) Pioneer species arrive at a site first but have lower survival rates than do species that arrive later.

D) Producing seeds that germinate at various times over long periods allows some plants to colonize sites that only occasionally present the right conditions for growth.

E) Large, long-lived seeds tend to result in large seed banks with short germination periods requiring favorable environmental conditions for development.

F) The successive appearance and disappearance of species on a site is a result of variation in species’ rates of invasion, growth, and survival.

托福阅读TPO31真题Part2原文及答案【含翻译】

Siam, 1851 – 1910

In the late nineteenth century, political and social changes were occurring rapidly in Siam (now Thailand). The old ruling families were being displaced by an evolving centralized government. These families were pensioned off (given a sum of money to live on) or simply had their revenues taken away or restricted; their sons were enticed away to schools for district officers, later to be posted in some faraway province; and the old patron-client relations that had bound together local societies simply disintegrated. Local rulers could no longer protect their relatives and attendants in legal cases, and with the ending in 1905 of the practice of forcing peasant farmers to work part-time for local rulers, the rulers no longer had a regular base for relations with rural populations. The old local ruling families, then, were severed from their traditional social context.

The same situation viewed from the perspective of the rural population is even more complex. According to the government’s first census of the rural population, taken in 1905, there were about thirty thousand villages in Siam. This was probably a large increase over the figure even two or three decades earlier, during the late 1800s. It is difficult to imagine it now, but Siam’s Central Plain in the late 1800s was nowhere near as densely settled as it is today. There were still forests closely surrounding Bangkok into the last half of the nineteenth century, and even at century’s end there were wild elephants and tigers roaming the countryside only twenty or thirty miles away.

Much population movement involved the opening up of new lands for rice cultivation. Two things made this possible and encouraged it to happen. First, the opening of the kingdom to the full force of international trade by the Bowring Treaty (1855) rapidly encouraged economic specialization in the growing of rice, mainly to feed the rice-deficient portions of Asia (India and China in particular). The average annual volume of rice exported from Siam grew from under 60 million kilograms per year in the late 1850s to more than 660 million kilograms per year at the turn of the century; and over the same period the average price per kilogram doubled. During the same period, the area planted in rice increased from about 230,000 acres to more than350,000 acres. This growth was achieve as the result of the collective decisions of thousands of peasants families to expand the amount of land they cultivated, clear and plant new land, or adopt more intensive methods of agriculture.

They were able to do so because of our second consideration. They were relatively freer than they had been half a century earlier. Over the course of the Fifth Reign (1868 – 1910), the ties that bound rural people to the aristocracy and local ruling elites were greatly reduced. Peasants now paid a tax on individuals instead of being required to render labor service to the government. Under these conditions, it made good sense to thousands of peasant families to in effect work full-time at what they had been able to do only part-time previously because of the requirement to work for the government: grow rice for the marketplace.

Numerous changes accompanied these developments. The rural population both dispersed and grew, and was probably less homogeneous and more mobile than it had been a generation earlier. The villages became more vulnerable to arbitrary treatment by government bureaucrats as local elites now had less control over them. By the early twentieth century, as government modernization in a sense caught up with what had been happening in the countryside since the 1870s, the government bureaucracy intruded more and more into village life. Provincial police began to appear, along with district officers and cattle registration and land deeds and registration for compulsory military service. Village handicrafts diminished or died out completely as people bought imported consumer goods, like cloth and tools, instead of making them themselves. More economic variation took shape in rural villages, as some grew prosperous from farming while others did not. As well as can be measured, rural standards of living improved in the Fifth Reign. But the statistical averages mean little when measured against the harsh realities of peasant life.

1. The word “severed” in the passage is closest in meaning to

A) cut off

B) viewed

C) protected

D) rescued

2. According to paragraph 1, the situation for Siam’s old ruling families changed in all of the following ways EXCEPT:

A) Their incomes were reduced.

B) Their sons were posted as district officers in distant provinces.

C) They could sell lands that had traditionally belonged to them.

D) They had less control over the rural populations.

3. According to paragraph 2, which of the following was true of Siam in 1905?

A) Its urban population began to migrate out of the cities and into the country.

B) Its Central Plain was almost as densely populated as it is today.

C) It was so rural that wild elephants and tigers sometimes roamed Bangkok.

D) It had many more villages than it did in the late 1800s.

4. The phrase “rice-deficient portions” in the passage is closest in meaning to

A) the parts that consume rice

B) the parts that do not have enough rice

C) the parts where rice is grown

D) the parts that depend primarily on rice

5. Paragraph 3 mentions all of the following as signs of economic growth in Siam EXCEPT

A) an increase in the price of rice

B) an increase in the amount of rice leaving Siam

C) an increase in the nutritional quality of the rice grown

D) an increase in the amount of land used for rice production

6. According to paragraph 3, farming families increased the amount of rice they grew in part by

A) growing varieties of rice that produced greater yields

B) forming collective farms by joining together with other farm families

C) planting rice in areas that had previously remained unplanted

D) hiring laborers to help them tend their fields

7. According to paragraph 4, what happened after the government ended the practice of requiring rural people to perform labor for it?

A) Rural people became more closely connected to the aristocracy.

B) Rural people spent more time growing rice for profit.

C) The government began to pay the laborers who grew rice for it.

D) The government introduced a special tax on rice.

8. Which of the following best describes the relationship between paragraphs 3 and 4 in the passage?

A) Paragraph 4 provides further evidence of the economic growth of Siam discussed in paragraph 3.

B) Paragraph 4 continues the discussion begun in paragraph 3 of farming improvements that led to economic growth.

C) Paragraph4 examines a particular effect of the Bowring Treaty mentioned in paragraph 3.

D) Paragraph 4 discusses the second of two factors that contributed to the expansion of rice farming mentioned in paragraph 3.

9. The word “dispersed” in the passage is closest in meaning to

A) spread out

B) gained power

C) adapted

D) specialized

10. The word “compulsory” in the passage is closest in meaning to

A) foreign

B) formal

C) required

D) preferred

11. According to paragraph 5, which of the following was true of Siam’s rural people during the Fifth Reign?

A) They were forced to spend most of the profits from rice growing on registrations required by the government.

B) Their lives remained very difficult even though statistics suggest that their quality of life improved.

C) The non-farmers among them were helped by the government more than the farmers among them were.

D) They were more prosperous when they were ruled by local elites than when they were ruled by the more modern government of the Fifth Reign.

12. According to paragraph 5, the government bureaucracy intruded in village life by

A) requiring the people to register their cattle and land

B) requiring the people to buy certain kinds of imported goods

C) discouraging the people from making handicrafts and tools

D) encouraging more people to take up farming

13.Look at the four squares [ ] that indicate where the following sentence could be added to the passage.

And yet, how is it that the peasants were able to choose to expand their economic activity in response to the market opportunities?

Where does the sentence best fit?

14. Prose Summary

During the late nineteenth century, changes in Siam’s power structure had important economic consequences.

Answer Choices:

A) Population movement occurred and rice cultivation intensified because Siam became more actively involved in international trade.

B) Changes in taxation and the ending of the requirement that people work part-time for the rulers allowed farmers to produce more rice for the marketplace.

C) Population increases occurred in part because Siam’s farmers were able to produce more rice to feed the population.

D) Land became so valuable that villagers had to pay the government for the land that they worked on.

E) Although rural living standards may have improved somewhat, prosperity varied from village to village and government bureaucracy played a greater role in village life.

F) Government modernization in the early twentieth century resulted in the loss of some freedoms that the rural population had gained from the traditional ruling classes.

托福阅读TPO31真题Part3原文及答案【含翻译】

Distributions of Tropical Bee Colonies

In 1977 ecologists Stephen Hubbell and Leslie Johnson recorded a dramatic example of how social interactions can produce and enforce regular spacing in a population. They studied competition and nest spacing in populations of stingless bees in tropical dry forests in Costa Rica. Though these bees do no sting, rival colonies of some species fight fiercely over potential nesting sites.

Stingless bees are abundant in tropical and subtropical environments, where they gather nectar and pollen from a wide variety of flowers. They generally nest in trees and live in colonies made up of hundreds to thousands of workers. Hubbell and Johnson observed that some species of stingless bees are highly aggressive to members of their species from other colonies, while other species are not. Aggressive species usually forage in groups and feed mainly on flowers that occur in high-density clumps. Nonaggressive species feed singly or in small groups and on more widely distributed flowers.

Hubbell and Johnson studied several species of stingless bees to determine whether there is a relationship between aggressiveness and patterns of colony distribution. They predicted that the colonies of aggressive species would show regular distributions, while those of nonaggressive species would show random or closely grouped (clumped) distribution. They concentrated their studies on a thirteen-hectare tract of tropical dry forest that contained numerous nests of nine species of stingless bees.

Though Hubbell and Johnson were interested in how bee behavior might affect colony distributions, they recognized that the availability of potential nest sites for colonies could also affect distributions. ?So as one of the first steps in their study, they mapped the distributions of trees suitable for nesting. ?They found that potential nest trees were distributed randomly through the study area. ?They also found that the number of potential nest sites was much greater than the number of bee colonies. ?What did these measurements show the researchers? The number of colonies in the study area was not limited by availability of suitable trees, and a clumped or regular distribution of colonies was not due to an underlying clumped or regular distribution of potential nest sites.

?

Hubbell and Johnson mapped the nests of five of the nine species of stingless bees accurately, and the nests of four of these species were distributed regularly. All four species with regular nest distributions were highly aggressive to bees from other colonies of their own species. The fifth species was not aggressive, and its nests were randomly distributed over the study area.

The researchers also studied the process by which the aggressive species establish new colonies. Their observations provide insights into the mechanisms that establish and maintain the regular nest distribution of these species. Aggressive species apparently mark prospective nest sites with pheromones, chemical substances secreted by some animals for communication with other members of their species. The pheromone secreted by these stingless bees attracts and aggregates members of their colony to the prospective nest site; however, it also attracts workers from other nests.

If workers from two different colonies arrive at the prospective nest at the same time, they may fight for possession. Fights may be escalated into protracted battles. The researchers observed battles over a nest tree that lasted for two weeks. Each dawn, fifteen to thirty workers from two competing colonies arrived at the contested nest site. The workers from the two colonies faced off in two swarms and displayed and fought with each other. In the displays, pairs of bees faced each other, slowly flew vertically to a height of about three meters, and then grappled each other to the ground. When the two bees hit the ground, they separated, faced off, and performed another aerial display. Bees did not appear to be injured in these fights, which were apparently ritualized. The two swarms abandoned the battle at about 8 or 9 A.M. each morning, only to re-form and begin again the next day just after dawn. While this contest over an unoccupied nest site produced no obvious mortality, fights over occupied nests sometimes kill over 1,000 bees in a single battle.

1. The word “rival” in the passage is closest in meaning to

A) established

B) competing

C) nearby

D) different

2. According to paragraph 2, some species of stingless bees are aggressive mainly toward

A) nonaggressive bees that forage on the same flowers

B) aggressive bees of other species

C) bees from their own colony

D) bees of their own species from different colonies

3. According to paragraph 3, Hubbell and Johnson hypothesized that

A) the distribution pattern of bee colonies determines the degree of aggressiveness the bees display

B) nests of nonaggressive bees have either a random or a clumped distribution, while nests of aggressive bees have a regular distribution

C) nests of nonaggressive bees are generally both closer together and more regularly distributed than those of aggressive bees

D) nests of aggressive bees tend to be more regular in shape than those of nonaggressive bees

4. According to paragraph 4, why did Hubbell and Johnson begin their study by mapping all the potential nest sites?

A) To determine whether the availability of potential nest sites played a role in the distribution of bee colonies

B) To know exactly where in the study area the colonies of all the different bee species were located

C) To be sure that suitable nesting sites were equally available in all parts of the study area

D) To find out whether different species of bees preferred different types of trees as potential nest sites

5. 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) The limited number of colonies was not due to the distribution or availability of potential nesting sites.

B) There was no lack of suitable trees or potential nesting sites in the study area.

C) The number of nests was directly related to the number or the distribution of suitable trees.

????D) Neither the number nor the distribution of colonies could be explained by the availability of suitable nest sites.

6. According to paragraph 5, Hubbell and Johnson determined

A) the order in which the colonies in the study area had been established

B) the level of aggressiveness of each of the nine species

C) the distribution pattern of the nests of five of the nine species

D) the number of colonies of each of the nine species

7. Why does the author indicate that “The fifth species was not aggressive, and its nests were randomly distributed over the study area.”?

A) To identify research results that contradicted Hubbell and Johnson’s original hypothesis

B) To indicate that research results confirmed that nest distribution was related to aggressiveness

C) To introduce the hypothesis that, within the same species, not all colonies are aggressive

D) To point out that both aggressive and nonaggressive species are equally successful at finding nest sites

8. The phrase “insights into” in the passage is closest in meaning to

A) tools to study

B) opportunities for

C) evidence of

D) an understanding of

9. According to paragraph 6, what is one result of using pheromones to mark nest sites?

A) The use of pheromones tends to result in nest clumping.

B) Pheromones attract animals other than bees to prospective nest sites.

C) Pheromones tend to make bees aggressive.

D) Pheromones secreted by bees of one colony also attract bees of other colonies.

10. The word “escalated” in the passage is closest in meaning to

A) intensified

B) transformed

C) combined

D) lengthened

11. Paragraph 7 supports which of the following ideas about fights over occupied nests?

A) They are more violent than battles over unoccupied nest sites.

B) They mostly occur between colonies of different species.

C) They are more frequent than battles over unoccupied sites.

D) They last longer than battles over unoccupied sites do.

12. Look at the four squares [?] that indicate where the following sentence could be added to the passage.

For example, a clumped distribution of nests might simply reflect a clumped distribution of suitable nesting sites.

Where does the sentence best fit?

13. Select from the seven sentences below the three sentences that correctly characterize aggressive species of stingless bees and the two sentences that correctly characterize nonaggressive species.

Answer Choices:

A) Nests are regularly distributed

B) Nests are sometimes located close together

C) Nests always occur in large clumps

D) Colonies are generally made up of fewer than 100 workers

E) Members of a colony feed alone or in small groups

F) Bees feed mainly on flowers that grow in high-density clumps

G) Nest spacing is maintained by fighting

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