( 2018 浙江卷)某二倍体高等动物( 2n=6 )雄性个体的基因型为 AaBb ,其体内某细胞处于细胞分裂某时期的示意图如下。下列叙述正确的是 A .形成该细胞过程中发生了基因突变和染色体畸变 B .该细胞含有 3 个四分体, 6 条染色体, 12 个 DNA 分子 C .该细胞每条染色体的着丝粒都连着两极发出的纺锤丝 D .该细胞分裂形成的配子的基因型为 aBX 、 aBXA 、 AbY 、 bY
【简答题】American schools begin in September after a long summer holiday. There are two terms in a school year, the first term is from September to January, and the second is from February to June. Most Americ...
【简答题】Most American children begin to go to school when they are five years old. American schools begin in September. There are two terms in a school year. The first term is from September to January, and t...