Answer:
control which substances enter the cell
Step-by-step explanation:
The fat soluble non-polar (hydrophobic)and the polar water soluble( Hydrophilic) simply describe the bi-layer structure of the cell membrane. The phospholipid bilayer is in such a way that the fat soluble hydrophobic tails point inwards towards one another,with the water soluble hydrophobic points outwards.
This arrangement ensure that polar molecules can only pass through the hyrophilic(water loving head),which points outwards while non-polar could only pass through the hydrophobic tails,which form the inner layer.
Thus the inner later only allow fat soluble substances passages,while the outer soluble layer allows only polar substances.
Therefore based on the arrangement of 1800,the cell membranes controls what enters the cell.