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1、 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：【王鑫托福阅读】托福 TPO 全集之 TPO29-2TPO 29-21. The phrase “mechanisms of natural selection” in the passage is closest in meaning toA types of natural selection B dangers of natural selection C problems natural selection solves D ways natural selection works2. Accordi
2、ng to paragraph 1, what is one effect of competition among individuals of different species?A It results in the eventual elimination of the resource for which they are competing.B It leads to competition among individuals of the same species.C It encourages new species to immigrate to an area.D It c
3、ontrols the number of individuals in the competing populations.3. The word “indigenous” in the passage is closest in meaning to A native B rate C most D numerous4.In paragraph 1, why does the author mention what happened in New Zealand?A To indicate that Darwin understood the importance of competiti
4、onB To illustrate that competition can lead to the extinction of speciesC To identify where the idea of competition among species first arose 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：D To argue against the idea that the process of selection is a natural occurrenceCompetitionWhen several individuals
5、 of the same species or of several different species depend on the same limited resource, a situation may arise that is referred to as competition. The existence of competition has been long known to naturalists; its effects were described by Darwin in considerable detail. Competition among individu
6、als of the same species (intraspecies competition), one of the major mechanisms of natural selection, is the concern of evolutionary biology. Competition among the individuals of different species (interspecies competition) is a major concern of ecology. It is one of the factors controlling the size
7、 of competing populations, and extreme cases it may lead to the extinction of one of the competing species. This was described by Darwin for indigenous New Zealand species of animals and plants, which died out when competing species from Europe were introduced.5. According to paragraph 2, competitio
8、n is not usually a significant factor among two coexisting species when A one of the species has only recently moved into the territory of the other B the species are closely related to each otherC the population of one species is much larger than that of the otherD both of the species are herbivore
9、s1. The word “graphically” in the passage is closest in meaning to A vividly B frequently C broadly D typically7.In paragraph 2, why does the author talk about what happened as a result of North and South America becoming joined at the Isthmus of Panama?A To make the point that predation can have as
10、 much effect on species survival as competition does B To show how the ability to switch to an alternative resource can give a species a competitive advantage C To account for the current species composition of North and South America 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：D To provide an example
11、 of the serious effects of competition between unrelated speciesNo serious competition exists when the major needed resource is in superabundant supply, as in most cases of the coexistence of herbivores (plant eaters). Furthermore, most species do not depend entirely on a single resource, if the maj
12、or resource for a species becomes scarce, the species can usually shift to alternative resources. If more than one species is competing for a scarce resource, the competing species usually switch to different alternative resources. Competition is usually most severe among close relatives with simila
13、r demands on the environment. But it may also occur among totally unrelated forms that compete for the same resource, such as seed-eating rodents and ants. The effects of such competition are graphically demonstrated when all the animals or all the plants in an ecosystem come into competition, as ha
14、ppened 2 million years ago at the end of Pliocene, when North and South America became joined by the Isthmus of Panama. North and South American species migrating across the Isthmus now came into competition with each other. The result was the extermination of a large fraction of the South American
15、mammals, which were apparently unable to withstand the competition from invading North American speciesalthough added predation was also an important factor.8. Paragraph 3 supports the idea that Gauses experiments were important because theyA provided a situation in which competition could be remove
16、d from the interaction between two species B showed that previous ideas about the extent to which competition determines the composition of a community were completely mistaken C helped establish that competition will remove all but one species from any given ecological niche D offered evidence that competition between species is minimal when there is an overabundance of a single food source9. Which of the sentences belo
