The intensity of the suns rays depends on the angle of which they hit the earth. In the summer mouths the angle at which the suns rays hit the earth is the steepest. Therefore the intensity is highest.
Control because it is used for observation to the rest of the experiment (:
The endomembrane system is very important for synthesizing, processing, and movement of lipids and proteins in the cell.
The smooth ER function is mainly used for lipid synthesizing and processing, while the rough ER function is for protein synthesizing
hope this helps