Question

阅读理解 　　Have you ever wondered why stems(茎)grow upwards and roots downwards? Why plants always seem to turn, towards the light and climbing plants run up rather than down? The answer is simple：auxin,a chemical substance that controls growth in plants． 　　Auxin gives away its secrets 　　Auxin is a plant hormone(激素)．Darwin was already interested in it in the 19th century．Only in recent years, however, has the hormone started to give away its secrets ,thanks to intensive molecular research．Auxin is produced in the young,growing parts of plants and then transported throughout the plant－to a low -lying stem for example．The stem needs to straighten out as soon as possible to be able to absorb the topside,resulting in the underside growing faster and the stem straightening out．For the same reason, plants in front of windows will always turn to the light．This active regulation of auxin transport allows plants to take ideal advantage of local and changing conditions． 　　A new means of transport for auxin? 　　The transport of auxin through the plant plays a vital role．And ,from all appearances,it is not a simple matter．The researchers identified an important new link and means of transport for auxin：PILS proteins(蛋白质)．PILS proteins are vital for auxin-dependent plant growth and adjust the intracellular(细胞内的)storage of the hormone．It is exactly this compartmentalizing(分类)of auxin that seems functionally important for the various developmental processes． 　　Growing crops more efficiently：the right amount of auxin in the right place 　　Higher auxin levels at the right moment and in the right place result in better growth and greater harvest．Better adjustment of auxin levels would make plants grow more efficiently．The researchers hope to contribute to the development of more efficient growing processes by continuing to sort out auxin transport processes． (1) Which of the following is true of ausin according to the text? [　　] A． It helps the plant to bend at the right places while growing． B． It prevents the roots of plants from growing faster． C． It is no use when the surroundings have changed． D． It helps the underside of plants grow faster than the topside． (2) Which of the following is true of auxin? [　　] A． It helps the plant to bend at the right places while growing． B． It helps the roots of plants to grow faster． C． It keeps the stems and roots from growing． D． It helps the stems to grow upward． (3) From Paragraph 3 we know that ________ [　　] A． the researchers are not so sure if the transport for auxin is a new one B． the levels of auxin remain the same during the growing processes of plants C． PILS proteins delay the growth of plants D． PILS proteins play an important part in the transport of auxin (4) According to Paragraph 2, the researchers got their results mainly by ________． [　　] A． referring to Darwin's theory B． observing plants straightening C． doing intensive molecular research D． watching plants in different places (5) Which of the following can be the best title for this passage? [　　] A． Why Plants Grow Towards the Light? B． Darwin's Dream Has Come True C． How Did Scientists Find Out the Secret? D． A New Way of the Growing of Plants

Answer 1

答案：1．D;2．D;3．C;4．C;5．A;
解析：

(1)	细节判断题。植物生长素的功能在第二段中体现的是resulting in the underside growing faster．
(2)	细节判断题。The researchers identified an important new link and means of transport for auxin：PILS proteins．PILS蛋白质在生长素的传播过程中起着至关重要的作用。
(3)	细节判断题。综合生长素的功能，对作物的成长体现最明显的就是向日葵。
(4)	细节理解题。达尔文一开始只是对生长现象感兴趣但并没有得出结论，只有现在的研究者经过了"密集的分子生物学研究"之后才得出结论。
(5)	解析：主旨大意题。文章一开始就以疑问的方式提出了主题，然后陆续揭示auxin的功能。 　　简述：属于科技题材，讲述了现代研究条件下对于植物生长素(auxin)的研究成果。