The contracting and relaxing of muscle is regulated by the amount of calcium present in the cells of muscle fibers. These cells must be able to move the calcium ions from areas with low concentrations to areas with high concentrations. What process would be necessary for this movement to occur? Osmosis Active Transport Passive Transport Facilitated Diffusion
I would say that active transport is the answer because it's from LOW concentration to HIGH concentrations, so it's going against the concentration gradients.
