<span>When a cell is in a dynamic equilibrium with its environment, this means that the salt/water concentration inside the cell is equal to the salt/water concentration outside the cell. It is called an equilibrium because no transport of molecules is needed since the concentrations are already the same.</span>
I am not really sure about the city, but if we look at the country, its BORDERS would be the same analogy for the cell membrane. I am saying this because cities dont really have a border .
