1. (2018·乐山会考) 选取三枝同一植物的长势相同的枝条分别标记为A、B、C， 作如下表的处理后，分别插入相同大小的、盛有等量蒸馏水的量筒中，并以石蜡油覆盖密封水面，置于适宜环境条件下。2小时后观察记录各组量筒中蒸馏水的减少量（说明：涂抹凡士林能堵塞叶片相应部位气体进出的通道）。请回答下列问题：                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

枝条编号	枝条处理	蒸馏水减少量
A	不作任何处理	2mL
B	凡士林涂抹所有叶片下表面	0.5 mL
C	除去枝条上的所有叶片	0 mL

1. （1） 石蜡油覆盖密封水面的目的是。
3. （2） 若要探究蒸腾作用的器官时，应选择（选择表中的字母番号填写）对照。若要探究气孔主要分布在叶片的上表面还是下表面时，应选择（选择表中的字母番号填写）对照。
5. （3） 如果实验时间由2小时缩短为1小时，但仍希望实验结果非常明显，可将适宜环境条件中的哪一环境因素适当提高？。
7. （4） 实验过程中，A、B两组枝条上的叶片的光合作用强度相比较，AB（选择“＜”或“＝”或“＞”填写）。