题干

1914年,匈牙利的科学家拜尔将燕麦胚芽鞘尖端放在去除胚芽鞘尖端的一侧,结果胚芽鞘向对侧弯曲生长。下列叙述正确的是(     )

A:该实验在黑暗中进行,可排除受光不均匀对实验结果的影响

B:该实验证明尖端确实能产生某种物质,该物质是吲哚乙酸

C:对照组是没有尖端的胚芽鞘,结果不生长

D:该实验证明了生长素在植物体内进行极性运输

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A

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    Bamboo is one of the world's most useful plants. For thousands of years, bamboo has been used in many different ways-from food to medicine to clothing and, in small ways, as a building material.

    However, bamboo is not often used as a building material in the developed world. A professor at the University of Pittsburgh in Pennsylvania is trying to change that. The professor and his students are testing the strength of bamboo.They are testing how much pressure or weight it can take before breaking.

    Kent Harries is a professor at the University of Pittsburgh. Harries says that testing methods for bamboo need to be the same for all. They need to be standardized. Standardizing test methods for bamboo will help to bring the plant into common use. It will also give engineers and builders around the world a dependable standard.

    Harries says that bamboo is strong in nature. The strength of at least three species of bamboo is similar to steel.Besides its strength, bamboo has other features that make it very useful in building. He says it is resilient(有弹力的), meaning it keeps its shape and strength even under pressure.

    Bamboo also grows quickly. Bamboo that is suitable for construction needs much less resources than wood. The harvest cycle of bamboo is about 3 years. Softwoods such as cedar, pine and spruce have a harvest cycle of about 10 years. And hardwoods that come from flowering plants such as oak and walnut need more than 30 years.

    Bamboo is widely used as food for panda bears. It is also used for flooring and window covers. However, for building, bamboo is not used much outside its native growing area. This is mostly because of its round shape. But there are other reasons too. People think -- or have the mentality--that bamboo is a low quality building material.