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.

　　Natural flavorings and fragrances are often costly and limited in supply. For example, the vital ingredient in a rose fragrance is extracted from natural rose oil at a cost of thousands of dollars a pound; an identical synthetic substance can be made for 1% of this cost. Since the early twentieth century, success in reproducing these substances has created a new industry that today produces hundreds of artificial flavors and fragrances.

　　Some natural fragrances are easily synthesized; these include vanillin, the aromatic ingredient in vanilla, and benzaldehyde, the aromatic ingredient in wild cherries. Other fragrances, however, have dozens, even hundreds of components. Only recently has it been possible to separate and identit3, these ingredients by the use of gas chromatography and spectroscopy. Once the chemical identity is known, it is often possible to synthesize them. Nevertheless, some complex substances, such as the aroma of fresh coffee, have still not been duplicated satisfactorily.

　　Many of the chemical compounds making up these synthetics are identical to those found in nature, and are as harmless or harmful as the natural substances. New products must be tested for safety, and when used in food, must be approved by the U.S. Food and Drug Administration.

　　The availability of synthetic flavors and fragrances has made possible a large variety of products, from inexpensive beverages to perfumed soap to used cars with applied "new car odor."

　　71. From the passage we can learn that ______

　　A. natural flavorings and fragrances are not quite dear

　　B. the limitation of natural flavorings and fragrances is clear

　　C. the supply of natural flavorings and fragrances is adequate to meet the demand

　　D. the cost of producing natural flavorings and fragrances is high

　　72. Which of the following is true according to the passage?

　　A. Natural rose fragrance is 100 times more expensive to produce than artificial rose fragrance.

　　B. The most important ingredient in a rose fragrance is obtained from natural rose oil at a low cost.

　　C. A different synthetic substance can be made for 1% of the cost.

　　D. Natural rose oil costs the same as its fragrances.

　　73. The industry of producing hundreds of artificial flavors and fragrances probably appeared in ______

　　A. 2000 B. 1953

　　C. 1909 D. 1810

　　74. According to the passage, all the following are easier to synthesize EXCEPT ______

　　A. aromatic ingredient in vanilla

　　B. vanilla

　　C. aromatic ingredient in wild cherry

　　D. the flavor of fresh coffee

　　75. The underlined word "duplicated" in Paragraph 2 is closest in meaning to ______

　　A. make double

　　B. make a copy of

　　C. produce something equal to

　　D. take from

　　76. Why does the author mention fresh coffee in Paragraph 2?

　　A. As an example of complex substances having not been duplicated satisfactorily.

　　B. Because the coffee fragrance is hard to produce.

　　C. To conclude the passage.

　　D. The smell of fresh coffee is inviting.

　　77. ______ a substance can be synthesized.

　　A. Upon identifying the basic components of it

　　B. Once chemically analyzed

　　C. When gas chromatography is used

　　D. If spectroscopy is adopted

　　78. It can be inferred from the passage that ______

　　A. vanillin is easier to synthesize than benzaldehyde

　　B. not all synthetic flavors are harmless

　　C. in general, the less components there are in a fragrance, the harder it is to synthesize

　　D. synthesized substances must be tested for safety only if they are used in food

　　79. Which of the following is the best title for tile passage?

　　A. How to Synthesize Fragrances

　　B. Synthetic Substances Are Easy to Make

　　C. Natural Flavorings and Fragrances

　　D. Synthetic Flavors and Fragrances

　　80. Which of the following is NOT true according to the last paragraph?

　　A. Synthetic fragrances can be used to make a used car smell like a new one.

　　B. Synthetic flavors and fragrances have added to the varieties of products.

　　C. Lemon soap is made out of some delicious lemon.

　　D. It is likely that a bottle of orange juice is synthesized.

KEYS：

　　61.A[分析] 主旨题型。

　　见本文主旨句，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.(第一段谈的是the study of isolated roots;第二段谈的是the relationship between shoots and roots)：因此选项A应为答案。

　　62.A[分析] 细节题型。

　　见第一段第一句：About fifty years ago，plant physiologists set out to grow roots by themselves in solutions in laboratory flasks，这里指plant physiologists自己培育根用作物;因此themselves在此应为正确选项。

　　63.B[分析] 细节题型。

　　见第一段第三句：They required sugar and the usual minerals and vitamins.所以选项B是答案。

　　64.A[分析] 细节题型。

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

　　65.C[分析] 推断题型。

　　第一段提到(块)根需要sugar and the usual minerals and vitamins，但不需要 organic nitrogen compounds，因(块)根可自造所需的蛋白质和其它organic compounds;这里反复提到的organic compounds应包括the high energy compound ATP(见第一段倒数第二句);因此可推断出选项C(一种化合物)为答案。

　　66.C[分析] 词义题型。

　　本句意为：对于分离出(孤立)的根所做的研究为了解根和芽作为一植物 _____的关系提供了帮助。当然intact应为：包括根和芽的植物整体，因此选项C为答案。

　　67.C[分析] 词义题型。

　　见第二段第四句：This comes in handy for the growth of buds in the early spring when leaves are not yet functioning.这对于芽(蓓蕾)在早春的生长很是必要，因为叶在那时还没有起作用。所以comes in handy应表“必要”，所以选项 C为答案。

　　68.D[分析] 推断题型。

　　见第二段第三、四句：根为芽提供有机氮，这对于芽(蓓蕾)在早春的生长很是必要，因为叶在那时还没有起作用。因此可推断出：在那时，植物的芽是从根处获得有机化合物的：所以选项D为答案。

　　69.C[分析] 主旨题型。

　　第二段第一句为本文的主旨。而这是植物生理学家通过研究种植在实验瓶中的根，及在此基础上研究根、芽作为植物整体间的关系取得的;本文对此作了较详尽的解释。因此选项C为答案。

　　70.B[分析] 推断题型。

　　根据本篇文章的结构和文体，不可能是一篇时事通讯(因发生在大约50年前)，也不会是一篇故事或小说;在此只可能是发表在一份专业刊物上，因此选项B为答案。

　　71.D[分析] 细节题型。

　　见第一段第一句：Natural flavorings and fragrances are often costly and limited in supply.因此选项D为答案。

　　72.A[分析] 是非题型。

　　见第一段第二句的后半部分：For example，the vital ingredient in a rose fragrance is extracted from natural rose oil at a cost of thousands of dollars a pound;an identical synthetic substance can be made for 1% of this cost.意即：玫瑰香(料)所需的成分是从天然玫瑰油中萃取的，这种萃取物一磅价值要数千美元;而人工合成的玫瑰香料价值只是天然的百分之一。因此选项A为答案。

　　73.C[分析] 细节题型。

　　见第一段第三句：Since the early twentieth century, success in reproducing these substances has created a new industry that…符合“二十世纪早期”条件的选项只有C，所以是答案。

　　74.D[分析] 细节题型。

　　本题可用排除法。见第二段第一句：Some natural fragrances are easily synthesized; these include vanillin，the aromatic ingredient in vanilla，and benzaldehyde，the aromatic ingredient in wild cherries.选项A、B、C的内容均被提及，因此除外的选项只有D，所以D为答案。(本题答案也可用下一题的推断法推出)

　　75.C[分析] 推断题型。

　　从第二段前几句得知：Some natural fragrances are easily synthesized.(有些天然香料可以很容易地进行人工合成。)Other fragrances，however，have dozens， even hundreds of components.(而有些却包含有几十甚至上百种成分——言外之意，较难合成。)Only recently has it been possible to separate and identify these ingredients by the use of gas chromatography and spectroscopy.(只是到了最近，由于使用气相色谱分析和分光镜才能分离或鉴别出这些成分。)Once the chemical identity is known，it is often possible to synthesize them.(一旦了解了它们的化学成分，人们就有可能将之合成。)Nevertheless, some complex substances, (然而仍有一些复杂的成分，如新鲜咖啡的香味难以合成得令人满意。);由此可推断出很难合成与新鲜咖啡香味相同的香料。选项C内容与此意最接近，所以是答案。

　　76.A[分析] 推断题型。

　　见上题推理：作者之所以提及新鲜咖啡，是借此例来说明一些成分复杂的物质很难令人满意地合成出来。所以选项A为答案。

　　77.B[分析] 细节题型。

　　见第二段倒数第二句(见75题答案)，所以选项B为答案。

　　78.B[分析] 推断题型。

　　见第三段第一句：Many of the chemical compounds…and are as harmless or harmful as the natural substances.由此推断出：有些化学合成物(其中也包括香料)与其自然界存在的物质一样是无害的，有些则是有害的。因此选项B为答案。

　　79.D[分析] 主旨题型。

　　阅读全文可知本文是围绕天然调味品和香料供应有限且价格不菲(见第一段第一句)，后有了人工合成品替代(尽管有些合成容易，有些困难)，使大量生产成为可能：其中主要部分谈的是人工合成品(调味品和香料)：因此选项D为答案。

　　80.C[分析] 细节题型。

　　可用排除法：选项A、D的内容见第四段后半句，选项B的内容见第四段前半句：只有选项C的内容未被提及(因为lemon柠檬属于natural substance，不是人工合成物)，所以是答案。