福建省厦门市2020-2021学年高二上学期期末考试英(7)

C

We know that carbon dioxide is a major driver of climate change, so the more that can be taken out of the atmosphere by plants, the better. With the warmer climate leading to a longer growing season, some scientists have suggested that more carbon dioxide would be absorbed by trees. But a new study has turned this theory on its head.

The researchers, led by Deborah Zani at the Swiss Federal Institute of Technology, studied certain tree species and recorded how much carbon each tree absorbed per season. With data from other projects, the researchers found as the rate of photosynthesis (光合作用) increased with warmer climate, leaves changed color and fell earlier in the year.

Climate-controlled experiments show what could be behind this unexpected result. In the trials, the trees were exposed to full sun, half shade or full shade. The results show there’s a limit to the amount of photosynthesis that a tree can carry out over a growing season and that certain trees can only absorb a set amount of carbon each year. Think of it like filling a bucket with water. It can be done slowly or quickly, but once the bucket is full, there’s nowhere for any more water to go.

Once that limit is reached, leaves begin to change color. The limit is set by the availability of nutrients, particularly nitrogen, which is a key nutrient that plants need to grow. The amount of available nitrogen often limits total growth. That’s why farmers and gardeners use nitrogen fertilizer.

These new findings have significant implications (启示) for climate change modelling. If we accept that warmer weather and longer growing seasons won’t allow trees to take up more carbon dioxide, carbon dioxide levels will rise more quickly than previously expected. The only way to change this will be to increase the capacity (容纳能力) of trees to absorb carbon.

27. What does the new study suggest?

A. More carbon dioxide would be absorbed by trees.

B. Global warming shortens the growing season of plants.

C. The amount of carbon dioxide decides the photosynthesis.

D. Warmer climate may cause leaves to change color earlier.

【主旨大意】本文是说明文，主要讲科学家发现植物在生长季节内通过光合作用吸收二氧化碳的能力是有极限的，随着吸收量增加超过能力上限，植物就更容易老化死去。容纳能力上限可能和植物可获得的氮有关。

【答案】D

【解析】本题属于细节题之多重细节题，考查获取事实性信息的能力．解题步骤：1.确定题干关键词：new study。2.定位原文。根据关键词可定位第一段和第二段。3.对比选项确定答案。

A项是新的研究出现前科学家的看法。(some scientists have suggested that more carbon dioxide would be absorbed by trees.)

B项表述与原文相反（With the warmer climate leading to a longer growing season）。

C项无提及且常识错误，二氧化碳量不能决定光合作用。

D项根据第二段最后一句the researchers found as the rate of photosynthesis (光合作用) increased with warmer climate, leaves changed color and fell earlier in the year. 可知，温暖的气候可能导致树叶更快变色。故选D选项。

28. How did the researchers carry out the study?

A. By analyzing collected data.

B. By measuring temperature.

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