According to a study published last week in the journal Science, scientists have found a way to change a plant’s genes (基因) in order to make it use sunlight more quickly. Someday, the results could increase the amount of food produced around the world.
By changing a plant’s genes, the scientists were able to increase leaf growth on plants by 14-20 percent. Specifically, scientists changed the plant’s protective (保护的) system. “Normally, this system is activated when a plant gets too much sunlight,” said scientist Krishna Niyogi, co-author of the study. “When the plant senses the light, it gets rid of extra energy and creates more leaves. When the plant is in the shade, the protective system is turned off. But the process is slow.”
Stephen Long is the lead author of the study. He compared a plant’s protective system to light-adjusting glasses. “When a person wears the glasses outside during the day, the lenses (镜片) darken and lighten depending on how sunny it is. Plants do the same thing,” he said. “But in plants the adjustment can take anywhere from 10 minutes to an hour. This makes it hard for plants to get the right amount of sunlight needed to create food.”
The new study sped up the process. By changing the plant’s genes, it’s more quickly than normal to turn on and turn off the protective system. 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 thought the genetic modification would produce the same results in corn or rice.
31. What does the plant’s protective system need to keep activated?
A.Mild shade. | B.Leaf growth. |
C.Genetic changes- | D.Enough sunlight. |
32. Why is the plant hard to get the right amount of sunlight?
A.Because it isn’t always sunny. |
B.Because leaf growth increases too slowly. |
C.Because the light-adjustment process is a bit long. |
D.Because the protective system is turned on and off more quickly. |
33. What does the underlined word “modification” in Paragraph 4 mean?
A.Development. | B.Decoration. |
C.Change. | D.Copying. |
34. What can we infer from this text?
A.Changing how a plant uses sunlight could mean more food in the future . |
B.When the plant is in the shade, its protective system is turned off slowly. |
C.Too much sunlight will damage plants’ protective system. |
D.It is hard for plants to create food without enough sunlight. |