Final answer:
Phospholipids have a hydrophobic tail and a hydrophilic head, and they arrange themselves into a lipid bilayer in water.
Step-by-step explanation:
A phospholipid is an amphipathic molecule that contains a hydrophobic tail and a hydrophilic head. The hydrophilic head of a phospholipid is composed of a phosphate group, while the hydrophobic tail consists of two fatty acid chains. In water, phospholipids spontaneously arrange themselves into a double layer called a lipid bilayer, with the hydrophilic heads facing outward and the hydrophobic tails sandwiched between them.