Hormones are transported through the blood stream to target cells.
The matrix (inside mito) has a negative charge compared to the intermembrane space (outside of mito but still inside) because positively charged protons are constantly pumped from the matrix to the intermembrane space. A cell oxidizes an organic molecule producing 3 NADH molecules and 3 FADH2 molecules..
In photosynthesis experiment, the effect of the light will be observe during the starch production- thus you need to have a plant without a starch to observe if the starch is produced during photosynthesis. Letting the leaves of the plant deprived from light for 48 hours will be forced to use its reserved starch making the storage of the starch decrease.