Final answer:
In a plasma membrane, the tails of the phospholipid molecules line up in a bilayer formation with the heads on the interior of the membrane. The tails orient towards polar molecules, while the heads point towards both extracellular and intracellular spaces.
Step-by-step explanation:
Phospholipids in a plasma membrane align their tails in a specific way. They orient their tails towards the polar molecules of water solutions and their heads in the interior of the membrane. This arrangement forms a bilayer where the hydrophilic heads point towards both the extracellular space and the intracellular space of the cell.