题干

下面是某同学在实验中遇到的一些问题,其中正确的操作或想法是()

A:在纸层析法分离叶绿体中色素的实验结果中,蓝绿色的色素带最宽,可判断为叶绿素a 在层析液中溶解度最高

B:探究温度对酶活性的影响,可选择过氧化氢溶液作为底物r

C:将某细胞内的I对同源染色体上的DNA用3H标记后,让其在不含放射性的环境中连续 进行2次有丝分裂,产生的子细胞中具有放射性的细胞有1个

D:在T2噬菌体侵染大肠杆菌的实验中,含35S的实验组若不搅拌、离心,则上淸液放射性 低,沉淀物放射性髙;含32P的实验组若保温时间过长,搅拌、离心后,则上淸液放射性髙, 沉淀物放射性低

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答案(点此获取答案解析)

D

同类题2

阅读下列短文,从下面每小题的A、B、C、D四个选项中选出最佳选项。

E

    For a Chinese kid, publishing(出版)a book in English is quite a big challenge. But Yang Nianhui,a 15-year-old student from Beijing,has done so.

    She wrote all English—language fantasy novel,The Vampires of Lorania.Foreign Language Teaching and Research Press has published it.It is their first time to publish a high school student's works independently.

    In Yang's 60,000-word novel,she describes a vampire kingdom called Lorania.A brave girl named Rose and a Chinese boy fight with bad guys to keep Lorania peaceful. It discusses the meaning of heroism from the view of a teenager.It tells readers,"A hero is one who chooses to stay and fight for what is right,even if he is afraid."

    Yang studies at the High School Affiliated with Renmin University of China(人大附中).She has spent over five years working on the book.

    As a big fan of English,Yang enjoys reading original novels and watching TV series in English.She is especially interested in fantasy novels.When she was in Grade 5,she read The Chronicles of Narnia by US author C S Lewis(《纳尼亚传奇》).It encouraged her to write her own novel.

    With little experience,she did run into some problems,like how to design the story.

    "I read many other fantasy novels to learn some things.And I kept changing and improving my draft again and again."she said.

    Yang is happy about publishing her first book."It gives me a chance to express my ideas,"she said.She has already started writing a sequel to her book.