题目

阅读理解     Hacking isn't just for computers and smart phones. According to a study, scientists have found a way to hack a plant's genes in order to make it use sunlight more quickly. Someday, the results could increase the number of food produced around the world.     Scientists used tobacco plants in the study because it is easy to change the plants' genes. Hacked plants are larger than normal plants.     Photosynthesis is the word used to describe how plants use sunlight, water and carbon dioxide to make their own food. Scientists say this is a very slow process. Plants use less than 1 percent of the energy. But by hacking a plant's genes, the scientists were able to increase the amount of leaf growth on plants between 14 and 20 percent. Scientists hacked the plant's protective system. Normally, this system starts when a plant gets too much sunlight. When the plant senses the light, it creates more leaves. When the plant is in shade, the protective system is turned off. But the process is slow.     The new study sped up the process by changing the plant's genes, the protective system turned on and off more quickly than normal. As a result, leaf growth on the plants scientists used in the study increased. Leaf growth on two plants increased by 20 percent, while leaf growth on a third plant increased by 14 percent. Scientists conducted the study on tobacco plants. But they think the genetic changes would produce the same results in corn and rice.     Agriculture professor Tala Awanda said the study makes sense, but cautioned the yield（产量）might not be quite so high for conventional food crops. Still, she added in an email, "this study remains a breakthrough," （1） Which of the following is true according to Paragraph 1 ? A . We can find hacking only in digital devices. B . A plant's genes can be changed by hacking. C . Hacking has been used in improving food production. D . Hacking can be used to change whatever you want. （2） Why did scientists choose tobacco plants to study? A . Because they are very easy to get. B . Because their genes are easy to change. C . Because they are larger than other plants. D . Because they can absorb sunlight quickly. （3） What do we know about photosynthesis? A . It helps plants to produce energy. B . It is regarded as a productive system for plants. C . It can increase leaf growth on plants by 14 percent. D . It is made up of sunlight, water and carbon dioxide. （4） We can learn from Paragraph 4 that changing the plants' genes proved _______. A . useless B . deadly C . effective D . unrealistic （5） What is Tala Awanda's attitude toward the study? A . Doubtful. B . Neutral. C . Objective. D . Critical. 答案： B B A C C

查看本题答案和解析