题目

As the smallestchild of his family, Alex is always longing for the time he should be able to be independent. 答案：【1】when下列对一个“四分体”的描述不正确的是A．含有4个DNA分子B．四分体的形成与DNA分子的复制有关C．含有一对同源染色体D．四分体中的姐妹染色单体之间可发生交叉互换