Answer:
Observe the graphic for the answer
Explanation:
1.- The first channel from left to right is the pump that exports protons, as you can observe, there are plenty of protons in the outside part, so the cell need to balance the quantity, that is the reason to be of a pump.
2.- The channel in the middle is the responsible for moving calcium, the same as the protons, from the outside part to the inside of the cell.
3.- The lactose carrier, that is the last channel, since the lactose is a carbohydrate that is quite big, needs a protein as a carrier to move it from the outside part to the inside, actually, some carriers can modify it shape as we can observe in the drawing to get inside some substances.
Hope this info is useful.
