下图的五个细胞是某一生物个体的不同细胞的分裂示意图。请回答以下问题: ( 1 ) A 、 B 、 C 、 D 、 E 中属于有丝分裂的是 ,属于减数分裂的是 。 ( 2 ) A 细胞有 条染色体,有 个 DNA 分子,属于 期。 A 细胞经分裂形成的子细胞中染色体有 条。 ( 3 )具有同源染色体的细胞有 。染色体与前一时期比,暂时加倍的细胞有 。染色体是体细胞两倍的是 。 ( 4 ) D 图处于分裂时期是 , D 细胞的名称是 ,其产生的子细胞的名称为 。
【简答题】阅读理解 Are you tired?Do you often catch colds and flu?If so, you might consider changing your sleep habits. Good health demands good sleep.Studies have shown that most people need eight hours of sleep e...
【简答题】Do you know why you sleep? You may think it’s because you’re tired. Or perhaps you’ve been told sleep is good for you. Yet no one knows exactly why or how people sleep. Until the early 1950s, most sci...