托福阅读真题+题目+答案：The Ecological Roles of Birds

托福阅读真题+题目+答案：The Ecological Roles of Birds

Birds provide numerous invaluable ecological services, and one of the most important is by scattering plant seeds. Seed dispersal enables plants to migrate into new territory and reduces competition with others of their own species, thereby increasing survival rates. In fact, if you enjoy spicy foods, you owe some appreciation to birds, who played a pivotal role in the evolution of chili peppers. In an example of evolutionary partnership, chili plants evolved in a way that offers birds a nutritious food source, while the plants benefited from the wide distribution of their seeds after passing through the birds’ digestive systems. Capsaicin is the molecule in spicy peppers that creates the sensation of heat we feel when it binds to pain receptors in the mouth. On a human tongue, a solution of just ten parts per million creates a distinct sense of burning, but nerve receptors in birds do not register the heat of capsaicin even if they ingest as much as twenty thousand parts per million.

1.The word "pivotal" in the passage is closest in meaning to

A early

B surprising

C crucial

D hidden

2. The word ''distinct" in the passage is closest in meaning to

A definite

B familiar

C unpleasant

D immediate

3.According to paragraph 1, which TWO of the following are benefits that birds provide? To receive full credit, you must select TWO answers.

A Birds help plants move into new territories.

B Birds help plants in their competition against other plant species.

C Birds increase the likelihood that plants will survive.

D Birds make it possible for humans to digest spicy plants.

Bird digestive systems also do the seeds of the chili pepper no harm, because many birds with a fondness for them have a rather short, straight digestive pipe through which food transits quickly. Researchers have even found snails that had been eaten by a bird, passed through its digestive tract, cast out the other end, and were still alive. Moreover, chili peppers can be plucked readily from the stem only when they are ripe, which means only those seeds ready to germinate (begin growing from a seed into a plant) are swallowed by the bird. Catching the eye of birds helps pepper plants expand their range. If mammals ate chilies, they would digest and destroy them or deposit them fairly close to the plant. Birds, however, drop the undigested seeds in faraway places. The cradle of chili pepper civilization is in Brazil, in a lowland region dubbed “the nuclear area” because it has the largest number of wild varieties of chilies in the world. It is believed that the first wild chili peppers sprang to life here and were spread across much of the Western Hemisphere by birds.

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