题目

细胞分化中不可能出现的变化有A.染色体的复制 B.某些细胞器的增添或消失C.细胞核的消失 D.细胞全能性的降低 答案：【答案】A【解析】关于“细胞分化”，考生可以从以下几方面把握：（1）细胞分化是指在个体发育中，由一个或一种细胞增殖产生的后代，在形态，结构和生理功能上发生稳定性差异的过程．（2）细胞分化的特点：普遍性、稳定性、不可逆性．（3）细胞分化的实质：基因的选择性表达．（4）细胞分完形填空。It is Christmas next week. The students are very ____. They are ____ for the holiday. Liu Tao is going to ____ the Shanghai Museum and the Bund with his family. The Bund is beautiful at night. Helen will ____ at home. She’s going to cook nice food ____ her family. She likes ____. She thinks ____ nice food makes people happy. Mike is going to watch the football match. He wants to be a football ____ in the future. ____ Mike’s dream come true, he needs ____ hard.【1】A.excitingB.excitedC.excitedlyD.feel excited【2】A.plansB.planingC.planningD.will plan【3】A.visitB.visitsC.visitedD.will visit【4】A.stayB.staysC.stayedD.staying【5】A.inB.atC.aboutD.for【6】A.cookB.cookingC.to cookD.cooks【7】A.eatsB.eatingC.ateD.to eat【8】A.playB.playersC.playerD.plays【9】A.To makeB.MakingC.MakesD.Made【10】A.workingB.to workC.workedD.work