题干

下列关于植物组织培养的叙述中,错误的是( )

A:培养基中添加蔗糖的目的是提供营养和调节渗透压

B:培养基中的生长素和细胞分裂素影响愈伤组织的生长和分化

C:离体器官或组织的细胞都必须通过脱分化才能形成愈伤组织

D:同一株绿色开花植物不同部位的细胞经培养获得的愈伤组织基因相同

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答案(点此获取答案解析)

D

同类题1

阅读理解, 阅读下列短文,从各题所给的A、B、C项中选出最佳选项,

    Language students often think they have memory problems. They worry because they can't remember words. In fact, the problem usually isn't with their memory. The problem is with how they study.

    To remember words better, you need to understand how memory works. There are two kinds of memories: short-term and long-term. When you see, hear, or read something, it goes first into short-term memory. But short-term memory lasts for only a few seconds. You will only remember something longer if it goes into long-term memory. Your long-term memory is like a very big library with many, many books. And like a library, it's organized (有条理的). When you put away a book – or memory – you can't just leave it anywhere. You have to choose a place where you can find it again.

    How can you do this with vocabulary? The answer is to work with the word and think about the word in new ways. You can do this by writing new sentences that include it. Even better, you can invent a little story about the word, with people or places that you know. Another way is to make a picture in your mind with the word. For example, if the word is height, you can think of the tallest person you know and try to guess his or her height. All of these activities are good ways to think about words. They make the meaning of words stronger in your long-term memory. And they give a way to find a word when you need it.