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读罢八九年高考生物试题,感到有几道题目的提法及标准答案有值得商榷之处。 1、第16道题:“动物细胞有丝分裂过程中,中心粒的分开和复制分别发生在:“A前期和后期 B 中期和末期 C 前期和末期 D 前期和中期”这里有两点值得讨论:(1)中心粒是否是复制产生的?在生物体中,复制必须要有DNA的存在,但不少实验证明中心粒并不存在DNA,因此中心粒中不存在遗传上有控制性状的结构,与线粒体和叶绿体是不一样的。其次,如果中心粒是复制的,那么在没有预先存在模板的情况下,也就不能复制。有实验表明,把正在进行分裂的海胆卵整个有丝分裂器去掉,其后还可以形成新的中心粒,其它还有一些实验可证明中心粒是新生,而不是复制的。《中学生物教学
After reading the 1989 college entrance examination biological examination questions, I feel that there are several questions on the formulation and standard answers that are debatable. 1, No. 16: “During the mitosis of animal cells, the separation and replication of the centrioles occur respectively in:” A Pre and post B Mid and late C Pre and post C Pre and mid D “There are two points worth discussing: 1) Is centrioles duplicated? In organisms, DNA replication must be present, but many experiments show that there is no DNA in the centrioles, so there is no genetically controlled structure in the centrioles, and Mitochondria and chloroplasts are different .Secondly, if the centrioles are duplicated, they can not be replicated without the presence of a preexisting template.Experiments have shown that the entire mitotic device of the dividing sea urchin eggs is removed, and thereafter There are also new centrosomes that can be formed, and a few other experiments have shown that centrosomes are new, not duplicated. ”Secondary biology teaching