Final answer:
Phospholipids are molecules that possess both hydrophilic and hydrophobic properties, making them crucial components of the plasma membrane due to their amphipathic nature.
Step-by-step explanation:
The molecule that has both hydrophilic and hydrophobic properties and would be found in plasma membranes is called a phospholipid. These molecules possess a hydrophilic head, which is attracted to water, and one or more hydrophobic tails, which repel water. In the structure of the plasma membrane, the phospholipid molecules arrange themselves into a bilayer, with the hydrophilic heads facing the aqueous environment on either side of the membrane and the hydrophobic tails facing each other, forming a barrier that excludes water from the membrane's core.
Phospholipids are amphipathic molecules, having both hydrophilic and hydrophobic regions. This characteristic is crucial for the formation of cellular membranes, allowing them to separate the cellular environment from the external surroundings while regulating the passage of substances in and out of the cell.