The relative concentration of each in the plasma membrane is partly regulated by the:

ion channels

Explanation:

The plasma membrane plays a critical role in regulating and maintaining ionic potential inside the cell, relative to ionic concentration present outside the cell. The ion channels are specific, in that they only recognize and allow particular ions to pass through and block the rest. Their opening and closing depends on the ionic potential during that time period.

blue stars have the highest surface temp

stellar distances are usually expressed in light-years

the measure of a star's brightness is called magnitude

hope this !

well the answer is 2!