如图是一个森林生态系统的植被生长情况，其他成分未表示出。有位科学家研究了图上的光合作用与光照强度之间的关系（图甲），及叶肉细胞中的相对含水量与光照强度之间的关系（图乙）。请据图分析回答：

⑴图甲中的a点（曲线与横轴交点）表示__________________________________________；b点（曲线与纵轴交点）时叶肉细胞产生ATP的细胞器是：______________。
⑵能够反映a点时生理过程及变量关系的是右上图中的                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
⑶测定森林乔木在炎热夏季一天中的光合作用时，往往发现光合作用强度要下降，原因是叶肉细胞中缺少_______（生理过程）的原料；与森林中人参、三七等植物光合作用相对应的是图甲中的曲线__________。
⑷图乙中表示乔木叶肉细胞的相对含水量与光照强度之间关系的曲线是________。
⑸假设将图中部分区域的乔木用无色细眼网一棵棵套住，则由于破坏了_________，网内乔木将凋亡。一段时间后，林下的灌木、草本植物也不能生存，其主要影响因素是________________________，试分析其原因________________________________________