题干

科学家把天竺葵的原生质和香茅草的原生质体进行诱导融合,培育出的驱蚊草含有香茅醛,能散发出一种特殊的气味,达到驱蚊且对人体无害的效果.下列关于驱蚊草培育的叙述中,错误的是(    )

A:驱蚊草的培育属于细胞工程育种,其优点是能克服远源杂交不亲和的障碍

B:驱蚊草培育过程要用到纤维素酶、果胶酶、PEG等试剂或离心、振动、电刺激等方法

C:驱蚊草培育过程是植物体细胞杂交,不同于植物组织培养,无愈伤组织和试管苗形成

D:驱蚊草不能通过天竺葵和香茅草杂交而获得是因为不同物种间存在生殖隔离

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答案(点此获取答案解析)

C

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根据短文内容,从短文后的选项中选出能填入空白处的最佳选项,并在答题卡上将该项涂黑。选项中有两项为多余选项。

      Sleep is something we all do. But some people need to sleep more than others. Babies sleep most of the time. Children in school sleep about ten to twelve hours a night. Most adults sleep only seven or eight hours.____All parts of our bodies have to rest after they work.. Our arms need a rest after we lift heavy thing, When we run fast, our legs work hard. They get tired. We have to rest them. Our brains workhard, too.____ We can sit quite still and rest our arms andlegs. But our brains aren't resting. They go right on thinking as long as weare awake.

      Our brains slow down a bit when we sleep and dream.____ Instead of thinking wide-awake thoughts, our brains make up dreams. Some dreams are very pleasing. Some are not. Most of thetime we forget them when we wake up.

      Scientists have tried to find out what would happen if people were not allowed to sleep. They asked some people not to go to bed. The people stayed up all night and all the next day. They stayed up the next night too,and the day after. They played games, but they made mistakes. They forgot things.____ The people grew rude and mean. They became angry with their friends. Finally they were too tired to stand up. When they sat down, they fell asleep.

      Scientists have found that if people are not allowed to sleep and to dream, they act in an unusual way.____But we do know that we need it to stay well. So tonight have a goodsleep. Lie down under the covers. Shut your eyes. Let your thoughts wander.Soon you’ll stop thinking. You'll be asleep.

A. It was hard for their tired brains to work.

B. When we are awake, they help us pay attention to the worldaround us

C. But babies, children, and adults----all of us need to haveour sleep

D. Good sleep helps to improve one's memory

E. No one knows why sleep is so good for us

F. But even as we sleep our brains are doing some work

G. Of course you will have a good sleep