How do phospholipids form a barrier between water inside the cell and water outside the cell?

Answer - Thanks to hydrophilic & hydrophobic. One is in the inner layer of the cell which is hydrophobic keeping water out. Where as the hydrophilic is getting water.

Reasoning - in the phospholipids there's a barrier called hydrophobic which keeps the water out coming in the cell which this is in the inner cell. While the hydrophilic likes water which is outside. These two dudes help the cell from exploding lol :)