30、Ⅰ为探究环境因素对植物光合作用强度的影响，设计进行如下实验：
实验材料和用具：图示实验装置(广口瓶容积为500mL)、100 mL量筒、200W的台灯、冷开水、不同浓度的NaHCO3溶液（冷开水配制）、黑藻等。实验重复三次，实验结果见下表。                                                                                                                                           
分析并回答下列有关问题：

（1）该实验中的自变量是           ，列出实验中的至少两个控制变量（无关变量）：
                                       
（2）试补充完成该实验探究的具体实验步骤。                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
①准备4套如图装置，编号为1----4，分别在各瓶中注入冷开水、0.1%NaHC0₃溶液、1.0%NaHC0₃溶液、5.0%NaHC0₃溶液各约500mL；
②取                                   ，分别放入各实验装置，并组装好实验装置；
③将4套装置            ，然后分别用                   ；
④30min后，                                      。
⑶由于黑藻自身呼吸作用会消耗氧气，故量筒中收集到的水的体积
不能表示为黑藻30min内的光合总量，请根据上表绘制出相关的
柱形图。


Ⅱ植物的光合作用受内、外多种因素的影响，如图是在20℃、0.03%CO₂浓度条件下，测得A、B两种植物在不同光照条件下光合速率变化曲线。请据图回答问题：
（1）图示表明，      植物更适宜在弱光照条件下生长，这是由植物本身的             决定的。生产上如果将A、B共同种植，形成群落的        结构，将可达到充分利用光能的目的。
（2）在昼夜周期条件下（12h光照、12h黑暗)，A植物需在光照强度___  __千勒克斯才能生长。
（3）当光照强度为8千勒克斯时，A植物每小时光合作用所制造的有机物量与B植物制造的有机物量的比例是        。