Did the greatest changes in weight occur in cells with the steepest concentration gradients

Yes, the greatest change in weight will occur in cells with the steepest concentration gradients. This is because, a high difference in the concentration gradient will leads to high rate of diffusion and molecules will move at a fast rate from the region of lower concentration to the region of higher concentration, thus osmosis will be occurring at a fast rate. But if the difference in concentration gradient is low, diffusion rate also will be slow and osmosis will also be slow.