About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course: The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.

　　The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.

　　61. What is the main topic of the passage?

　　A. The relationship between a plant's roots and its shoots.

　　B. What can be learned by growing roots in isolation.

　　C. How plants can be grown without roots.

　　D. What elements are necessary for the growth of plants.

　　62. The underlined word "themselves" in Paragraph 1 refers to ______

　　A. plant physiologists B. solutions

　　C. laboratory flasks D. roots

　　63. The scientists found what the isolated roots need is ______

　　A. quite natural

　　B. sugar, minerals and vitamins

　　C. some rare vitamins

　　D. organic nitrogen compounds

　　64. Roots have the ability to ______

　　A. make proteins

　　B. obtain fresh air

　　C. produce inorganic nitrogen

　　D. carry out activities without energy

　　65. According to the passage, what is ATP?

　　A. A biochemical process.

　　B. The tip of a root.

　　C. A chemical compound.

　　D. A type of plant cell.

　　66. The underlined word "intact" in Paragraph 2 is closest in meaning to ______

　　A. mature B. wild

　　C. whole D. tiny

　　67. The use of the phrase "comes in handy" underlined in Paragraph 2 indicates that the process is ______

　　A. unavoidable B. predictable

　　C. necessary D. successful

　　68. It can be inferred from the passage that, in the early spring, the buds of plants ______

　　A. "export" protein in the form of amino acids

　　B. do not require water

　　C. have begun photosynthesizing

　　D. obtain organic compounds from the root

　　69. Which of the following best describes the organization of the passage?

　　A. The results of two experiments are compared.

　　B. A generalization is made, and several examples of it are given.

　　C. The findings of an experiment are explained.

　　D. A hypothesis is presented, and several means of proving it are suggested.

　　70. Where is this passage likely to be found?

　　A. A newsletter. B. A magazine.

　　C. A storybook. D. A novel.

　　KEYS：

　　61.A[分析] 主旨題型。

　　見本文主旨句，第二段第一句：The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants.(第一段談的是the study of isolated roots;第二段談的是the relationship between shoots and roots)：因此選項A應(yīng)為答案。

　　62.A[分析] 細(xì)節(jié)題型。

　　見第一段第一句：About fifty years ago，plant physiologists set out to grow roots by themselves in solutions in laboratory flasks，這里指plant physiologists自己培育根用作物;因此themselves在此應(yīng)為正確選項。

　　63.B[分析] 細(xì)節(jié)題型。

　　見第一段第三句：They required sugar and the usual minerals and vitamins.所以選項B是答案。

　　64.A[分析] 細(xì)節(jié)題型。

　　見第一段第六句：Roots are capable of making their own proteins and other organic compounds.所以選項A是答案。

　　65.C[分析] 推斷題型。

　　第一段提到(塊)根需要sugar and the usual minerals and vitamins，但不需要 organic nitrogen compounds，因(塊)根可自造所需的蛋白質(zhì)和其它organic compounds;這里反復(fù)提到的organic compounds應(yīng)包括the high energy compound ATP(見第一段倒數(shù)第二句);因此可推斷出選項C(一種化合物)為答案。

　　66.C[分析] 詞義題型。

　　本句意為：對于分離出(孤立)的根所做的研究為了解根和芽作為一植物 _____的關(guān)系提供了幫助。當(dāng)然intact應(yīng)為：包括根和芽的植物整體，因此選項C為答案。

　　67.C[分析] 詞義題型。

　　見第二段第四句：This comes in handy for the growth of buds in the early spring when leaves are not yet functioning.這對于芽(蓓蕾)在早春的生長很是必要，因為葉在那時還沒有起作用。所以comes in handy應(yīng)表“必要”，所以選項 C為答案。

　　68.D[分析] 推斷題型。

　　見第二段第三、四句：根為芽提供有機(jī)氮，這對于芽(蓓蕾)在早春的生長很是必要，因為葉在那時還沒有起作用。因此可推斷出：在那時，植物的芽是從根處獲得有機(jī)化合物的：所以選項D為答案。

　　69.C[分析] 主旨題型。

　　第二段第一句為本文的主旨。而這是植物生理學(xué)家通過研究種植在實驗瓶中的根，及在此基礎(chǔ)上研究根、芽作為植物整體間的關(guān)系取得的;本文對此作了較詳盡的解釋。因此選項C為答案。

　　70.B[分析] 推斷題型。

　　根據(jù)本篇文章的結(jié)構(gòu)和文體，不可能是一篇時事通訊(因發(fā)生在大約50年前)，也不會是一篇故事或小說;在此只可能是發(fā)表在一份專業(yè)刊物上，因此選項B為答案。