托福阅读真题+题目+答案：Mesozoic Seed Dispersal

托福阅读真题+题目+答案：Mesozoic Seed Dispersal

Many plants rely on wind to disperse(spread)their seeds. ⬛ However, because seeds often fall into the wrong places. wind dispersal seems wasteful; it can work only in plants that produce great numbers of seeds. ⬛ Wind-dispersed seeds must be light and small, so they cannot carry much energy for seedling growth. ⬛ They have to germinate(grow from a seed) in relatively well-lit areas, where they can obtain energy from sunlight. ⬛ Alternatively, a plant could have its seeds carried away by an animal and dropped into a good place for growth. Many animals can carry larger seeds, which can successfully germinate in darker places. Some animals visit plants to feed on pollen or nectar, and others eat parts of the plants. Others simply walk by the plant, brushing it as they pass. Small seeds may be picked up accidentally during such visits, especially if the seed has special hooks, burrs, or glues to help attach it to hairy or feathery visitor.

1.According to paragraph 1, all of the following are true of small seeds EXCEPT:

O They usually fall in places where they successfully germinate.

O They cannot carry much energy for germination.

O They sometimes have ways to attach themselves to animals.

O They are dispersed both by wind and by animals passing by.

However, seed dispersal by animals is not cost-free. Many dispersers eat the seeds, passing only a few undamaged through their internal organs. So there is a significant wastage of seeds, depending on a delicate balance between the seed coat and the teeth and stomach of the disperser. Too strong a seed coat, and the disperser will turn to easier food or germination will be too difficult; too weak a seed coat, and too many seeds will be destroyed. Some plants' seeds germinate well only if they are eaten by a particular disperser.

2.Paragraph 2 answers which of the following questions?

O Why is animal dispersal more effective than wind dispersal?

O What causes some seeds to have strong coats and some to have weak ones?

O What are the steps in the process by which animals pass seeds through their stomach after eating them?

O What factors contribute to whether or not the seeds dispersed by animals will successfully germinate?

Scientists believe animals first began dispersing seeds sometime during the Mesozoic era(252-65 million years ago). Seed dispersal by animals surely evolved after insect pollination. Insects of the Jurassic period (206-145 million years ago) may have become good pollinators, but they were too small to have been large-scale seed transporters. Jurassic reptiles (including dinosaurs)were large enough, but often had low food-processing rates, so any seeds they swallowed were exposed to digestive juices for a long time. Reptiles do not even have fur in which seeds can be entangled (though feathered therapod dinosaurs might have). Seeds were undoubtedly dispersed by dinosaurs to some extent, since the huge vegetarian dinosaurs ate great quantities of vegetation. But in spite of the size of the deposits of fertilizer (in the form of waste) that must have surrounded seeds passing through dinosaur, browsing dinosaurs (ones that eat grass, leaves, and shrubs) probably damaged and trampled plants more than they helped them. It is unlikely that any Mesozoic plant would have encouraged dinosaur browsing.

3.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.

O Browsing dinosaurs, the ones that ate grass, leaves, and shrubs, produced large deposits of fertilizer in the form of waste.

O Seeds that passed through a dinosaur would have been surrounded by large deposits of waste that must have served as fertilizer.

O Dinosaurs probably damaged plants more by trampling them than they helped them by depositing and fertilizing their seeds.

O The size of the plants that a dinosaur browsed probably determined how likely it was that they would be destroyed or trampled

4.According to paragraph 3, which TWO of the following could explain why many Jurassic reptiles were not good seed dispersers? To receive credit, you must select TWO answers.

A Food stayed in their digestive system for a long time

B They were not covered by fur.

C They did not travel very far or very fast.

D They did not eat sufficient quantities of plants.

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