题目

In England, people often talk about the weather because they can experience (经历) four seasons in one day. In the morning the weather is warm just like in spring. An hour later black clouds come and then it rains hard. The weather gets a little cold. In the late afternoon the sky will be sunny, the sun will begin to shine, and it will be summer at this time of a day. In England, people can also have summer in winter, or have winter in summer. So in winter they can swim sometimes, and in summer sometimes they should take warm clothes. When you go to England, you will see that some En 根据下图所示的细胞分裂图像回答问题： （1）写出A～D细胞的分裂方式和时期： A．________，________；B．________，________；C．________，________；D．________，________。 （2）在A～F图中，染色体中肯定含有两个DNA分子的细胞是________，染色体中肯定含有一个DNA分子的细胞是________。 （3）在A～F图中，含有同源染色体的细胞是________。含有两个染色体组的细胞是________，染色体暂时加倍的细胞是________。 （4）设正常体细胞DNA含量为“2a”，则DNA含量为“4a”的细胞是________，DNA含量为“2a”的细胞是________，DNA含量为“a”的细胞是________。 （5）在A～F图中，能发生在2n＝4的生物体内的细胞分裂图像是________。 （6）在A～F图中，________可称为正常体细胞，________可称精子细胞或卵细胞，________可称为初级性母细胞，________可称为次级性母细胞。