Answer:
A cell needs a gateway because the cell needs to taken in food and remove waste.
Explanation:
Cell membrane acts as a gateway to the cell. A clear separation has to be maintained between the interior and exterior of the cell. It is the function of cell membrane to maintain this separation.
Cell membranes are mainly composed of lipids, proteins and carbohydrates. The movement of substances to the inside and outside of the cell is facilitated by the cell membrane.
Depending on whether energy is expended or not transport across cell membrane can be passive or active.
