植物光合作用主要通过叶片进行，叶片的结构包括______、______、______三部分．-生物

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• 将一片刚摘下的菠菜叶片浸在盛有70℃热水的烧杯中，发现叶片背面产生的气泡数比正面多．该现象说明菠菜叶片的（）A．背面气孔数较多B．背面颜色较深C．正面气孔数较多D．正面颜色较深-生物
• 下图是蚕豆叶不同切面结构示意图。在低倍镜视野下观察到数目最多的细胞是[]A．②B．③C．④D．⑤-七年级生物
• 关于气孔的开闭叙述正确的是[]A．气孔白天开放，夜晚关闭B．气孔热天开放，冷天关闭C．气孔在浇水时开放，施肥时关闭D．气孔在保卫细胞吸水时开放，保卫细胞失水时关闭-八年级生物
• 要观察菠菜叶的保卫细胞和气孔，应选用下列哪种玻片标本[]A．菠菜叶的横切片B．菠菜叶的纵切片C．菠菜叶的上表皮装片D．菠菜叶的下表皮装片-七年级生物
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• 下图为叶片的结构示意图，请据图回答：(1)[2]_______和[4]_______合称表皮，起保护作用。(2)[3]是_______，在其中含有大量的叶绿体，所以叶片呈绿色。(3)[5]是由一对__
• 叶片与外界环境之间进行气体交换的门户是[]A．表皮B．气孔C．叶肉D．叶脉-七年级生物
• 将叶片的叶脉切断，产生的影响是[]A．光合作用不能顺利进行B．物质运输受阻C．叶片不能进行正常伸展D．以上说法均正确-七年级生物
• 将一片刚摘下的菠菜叶片浸在盛有70℃热水的烧杯中，发现叶片背面产生的气泡数比正面多。该现象说明菠菜叶片的[]A．背面气孔数较多B．背面颜色较深C．正面气孔数较多D．正面颜色较-八年级生物
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