2018年6月30日托福阅读真题+题目+答案：The Angiosperm Revolution 

2018年6月30日托福阅读真题+题目+答案：The Angiosperm Revolution 

Of all the kinds of modern land plants one group dominates: the angiosperms, or flowering plants. With over 250,000 living species, they are the majority of plants of most habitats- except marine environments, which are still habitats for the more primitive algae. But angiosperms were a comparatively recent development in plant evolution. They arose in the mid-Mesozoic (approximately 200 million years ago to 145 million years ago), but by about 100 million years ago they had pushed the conifers (plants having cone-shaped reproductive structures rather than flowers for reproduction) into the background. Even earlier types of plants such as ferns are now restricted to certain wet habitats, and many of the dominant gymnosperms (plants with exposed seeds, such as conifers) of the early Mesozoic have now been largely replaced by angiosperms; the formerly dominant gymnosperms that did not become completely extinct now survive in comparatively few places.

1.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 Angiosperms gradually replaced gymnosperms and ferms when these became extinct during the early Mesozoic.

O Angiosperms began to evolve from earlier plants such as gymnosperms during the late Mesozoic, and gymnosperms now exist only as ferns in certain wet habitats.

O Angiosperms have replaced gymnosperms, even in the wet habitats where gymnosperms were formerly dominant.

C Angiosperms succeeded at the expense of earlier plants such as fems and gymnosperms, which now exist in limited habitats or have become completely extinct.

2.What can be inferred from paragraph 1 about conifer plants?

O They were more common than angiosperms through the mid- Mesozoic.

O Like angiosperms, they are a relatively recent development in plant evolution.

O They can be found in most of the same habitats as angiosperms.

O They arose at about the same time as ferns.

Why were the angiosperms so successful? ⬛ A major advantage they have over more primitive plants is their efficient mode of reproduction- -the flower and all of its complex reproductive mechanisms that ensure success. Instead of the inefficient wind-pollinated gymnosperm seed, which wastes a huge amount of pollen and is dependent on random breezes, angiosperms have evolved flowers specifically as devices to attract pollinators- -mainly insects (especially moths, butterflies, and bees) but also birds, bats, and other flying creatures. ⬛ The pollinators ensure that the pollen is carried directly from one flower of the same species to another, which is more efficient than relying on the wind. ⬛ This process of delivery is called cross-pollination. ⬛ The reproductive cycle is highly modified: the ovules (egg-producing organs) are fully enclosed within protective covers called carpels, which form the core of the flower. The carpel protects the ovule from drying out, from fungal infection, and from predation by plant-eating insects. Pollen-producing organs called stamens are surrounded by petals (which serve to attract the pollinator and guide it to the ovules in many cases) and an outer covering of sepals for protection. Typically, a pollinator gets pollen stuck onto it as it climbs into a flower, seeking the nectar that is generated to lure it. The ovule is usually pollinated by the sperm carried from a different flower, thus minimizing self-fertilization (but angiosperms can also self-fertilize if cross-pollination is not possible).

3.The word “random” in the passage is closest in meaning to

O rare

O seasonal

O steady

O chance

4.According to paragraph 2, which of the following describes the most common method of fertilization used by angiosperms?

O Pollen is transported from one flower to another by the wind.

O Pollinators deposit pollen as they move from flowers of one species to flowers of other species.

O Angiosperms pollinate their own ovules in a process called self- fertilization.

O Pollen is carried from one flower to another by a flying insect or other creatures.

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