如图1是某高等生物在生殖发育过程中细胞内染色体数目的变化曲线，图2表示细胞内核DNA与染色体数目比值的变化关系．请分析回答：

（1）图l中同源染色体分离发生在A过程的　____ （填数字标号）阶段．B过程中④到⑤染色体数目加倍的原因是____ ．

（2）图2中de段变化的原因是____，对应图l中C过程的____ （填数字标号）阶段．

（3）图2若表示减数分裂过程中的相关变化，则ac段对应的时期是____ ，此时细胞中发生的主要变化是____ 

（4）图2若表示有丝分裂过程中的相关变化，则cd段对应的时期是____ ．  在“观察根尖分生组织细胞的有丝分裂”实验中，装片的制作流程为____ ，将装片放在显微镜下观察，视野中处于____ 时期的细胞最多．

如图，D是△ABC的边AB上一点，在条件（1）∠ACD=∠B，（2）AC²=AD•AB，（3）AB边上与点C距离相等的点D有两个，（4）∠B=∠ACB中，一定使△ABC∽△ACD的个数是（　　）

实验的基本过程如下：

Ⅰ．将蚕豆幼苗培养在含有³H的胸腺嘧啶核苷的培养基上，培养一段时间后，观察细胞分裂中期染色体的放射性情况．

Ⅱ．当DNA分子双链都被³H标记后，再将根移到含有秋水仙素的非放射性培养基中，培养一段时间后，观察细胞分裂中期染色体的放射性情况．

请回答相关问题：

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