2019年12月21日托福阅读真题+题目+答案：Surviving as a Conifer

2019年12月21日托福阅读真题+题目+答案：Surviving as a Conifer

Conifers, including pine and spruce trees, belong to the category of non-flowering plants known as gymnosperms. (Flowering plants known as angiosperms, include broad-leaved trees such as oaks.) Conifers live predominantly in nutrient-poor soils or harsh climates-difficult conditions for the growth of most other plants-yet there is no evidence that they prefer such locations to others. Indeed, many species experiencing these conditions in their natural habitat grow exceedingly well if planted in fertile soils. It appears that conifers have adapted to these environments to avoid competition from angiosperms, in particular fast-growing, large-leaved herbs, shrubs, and trees. While many studies show that conifers can be more productive than angiosperms in terms of the amount of carbon or wood produced, each tree is slow to attain this overall growth and thus placed at an early disadvantage, and it is this slow start, compared with that of angiosperms, that has driven conifers to marginal habitats. Only in places where conditions are poor for plant growth in general do immature conifers have a natural chance against other plants. But how do conifers overcome the handicaps of nutrient-poor soils and short growing seasons? What are the adaptations that nave allowed them to prosper under these limitations?

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

A.However

B.Often

C.In fact

D.In turn

2.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.Conifers can produce more carbon or wood than angiosperms, leaving angiosperms at an early disadvantage when driven to marginal habitats.

B.Despite their productivity, conifers are placed at an early disadvantage compared with angiosperms because they grow in marginal habitats.

C.Studies showing that conifers are more productive than angiosperms also explain why conifers have been driven to marginal habitats.

D.Conifers can produce more carbon or wood than angiosperms, but their slow start at growth compared with that of angiosperms has driven them to marginal habitats.

With regard to soil conditions, a plant uses its root system to take up water from the soil in which minerals, including necessary nutrients such as nitrogen, phosphorus, and potassium, are dissolved.▋ Root systems can be very extensive and provide as much plant surface underground as the crown with leaves provides aboveground.▋ Yet in nutrient-poor soil extensive root systems are still not enough. ▋The surface must be enlarged to take in enough of the very little nutrients that become available from the weathering of rock (rock that wears away) and bacterial activity decomposing organic matter.▋ This is done through the symbiotic (mutually advantageous) relationship of plant roots with mycorrhizal fungi. Fungi have extensive underground networks of hyphae, or fine fungal threads. The hyphae of mycorrhizal fungi form numerous connections with the tips of roots, replacing the hair roots, the smallest roots of a shrub or tree responsible for water and nutrient uptake. These fungi greatly extend the root length and surface-in some experimental trials with pine seedlings by 10,000 times. The hyphae handle the task of taking up water and nutrients. This results in greatly increased growth rates of the seedlings, despite the fact that the fungus takes something in return, the biochemical building blocks (molecules) for growth. It leaves more than enough for the tree to grow faster than without fungi. Almost all conifers, and some other plants such as orchids, have mycorrhizae on which they totally depend. Although mycorrhizal symbiosis also occurs in angiosperm trees such as birches, beeches, and oaks, it is absent or poorly developed in many others. Generally, in fertile soils mycorrhizal colonization is much reduced, so that most angiosperms did not evolve the ability to form these symbiotic relationships. We can see lots of mushrooms (fungal fruiting bodies) in forests on fertile soils, but they are mostly not mycorrhizal fungi.

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