Final answer:
Phospholipids orient themselves in the same direction in the plasma membrane because their hydrophobic tails face each other and their hydrophilic heads face outwards.
Step-by-step explanation:
This characteristic is vital to the structure of a plasma membrane because, in water, phospholipids tend to become arranged with their hydrophobic tails facing each other and their hydrophilic heads facing out. In this way, they form a lipid bilayer-a double layered phospholipid barrier that separates the water and other materials on one side from the water and other materials on the other side.