Why is it important for cells to have osmotic blance wih their external enviroment?
Because every cell has its limit in storing and utilizing a said organic substance like the amount of water, a solution's ph and salinity. Each cell attains and processes to maintain homeostasis which is defined as the balance between the internal and external environment, adapting for instance for a cell to survive. That is why, the follow of water and other gradients is gradual and continuous. There are various interdependent system that actually manages every movement of every system in order to maintain homeostasis, plainly every set function is a coordinated body system response.