19．下列不属于生态系统的是················································································(　 )

A．一个池塘中所有的生物　　 B．一片森林　 　C．一块稻田　　 D．生物圈

18．在探究“光对鼠妇生活的影响”实验中，实验的变量是····························(　 )

A．光　　　　　 B．温度　　　　 C．湿度　　　　　 D．周围的环境

17．细胞分裂过程的正确顺序是············································································(　 )

①细胞质分成两份，每份各含有一个细胞核　　 ②在原来的细胞中央，形成新的细胞膜，植物细胞还形成新的细胞壁　　 ③细胞核由一个分成两个

A． ①②③　　　 B． ②①③　　　 C． ③①②　　　　 D． ①③②

16．生物体不会因个体死亡而导致物种灭绝，这是因为生物体具有················(　 )

A．生长特征　　　 B．适应性　　　　 C．繁殖特征　　　 D．遗传特征

15．人们吃香蕉时，吃的是····················································································(　 )

A．细胞质　　　　 B．保护组织　　　 C．机械组织　　　 D．营养组织

14．在做“光对鼠妇生活的影响”实验时，用10只鼠妇做实验，并算出全班同学平均值的目的是···················································································································(　 )

A．有利于观察　　 B．容易确定变量　 C．减少误差　 D．使鼠妇能自由运动

13．当我们梳头时常有一些头屑落下来，头屑属于··············································(　 )

A．细胞死亡了的结缔组织　　　 　B．细胞死亡了的肌肉组织

C．细胞死亡了的神经组织　　 　　D．细胞死亡了的上皮组织

12．在动物体内分布最广的组织是··········································································(　 )

A．结缔组织　　　 B．上皮组织　　　　 C．肌肉组织　　　 D．神经组织

11．一棵小树苗能长成一棵参天大树的奥秘是······················································(　 )

A．细胞的生长使体积增大　　　　　　　　 B．细胞分裂使细胞的数量增多

C．细胞的体积增大与细胞的数量增多共同作用　 D．细胞吸水膨胀所致

10．在观察细胞时，视野中出现了一个污点，移动玻片转动目镜，污点都没有动，则说明污点在················································································································· (　 )

A．目镜上　　　 B．玻片上　　　 C．物镜上　　 D．反光镜上