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 to the calcium ions from areas with low concentrations to areas with high concentrations. what process would be necessary for this movement to occur?

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit