题干

观察口腔上皮细胞中DNA和RNA的分布实验中,加入8%盐酸的作用不包括(    )

A:促使细胞膜上蛋白质变性,利于染色剂进入细胞

B:改变细胞膜通透性,加速染色剂进入细胞

C:促使染色体中的DNA与蛋白质分离,利于染色

D:促使染色体中的DNA解旋,有利于与染色剂结合

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答案(点此获取答案解析)

D

同类题5

Dear Nancy,
   How are you? Now I want to tell something interesting. Last week we had a trip to Mount Tai. On Tuesday we went to Taian by bus, a city at the foot of the mountain. We had a good rest at a hotel. At about one o'clock early the next morning, we began to climb the mountain. It took us about four hours and a half to get to the top. The mountain is covered (覆盖) with trees. I didn't see such a beautiful place before.
   “Look! The sun is going to rise!” my friend Lim shouted.
   We all turned to the east and watched. Soon half of the sky because white, and a big, red ball was rising slowly. A few minutes later, the sky became bright(明亮的).
   We stayed on the top and had a good time. After lunch we started going down. We got to the tour hotel at about four in the afternoon. Though we were tired, we were very happy. We came back to school the next day.
   Thank you very much for your last letter and the beautiful postcards. Hope to hear from you soon.
                                                                                                                                                        Yours
                                                                                                                                                       Wu Tong