Final answer:
A phospholipid is the molecule with a hydrophilic head and two hydrophobic tails, playing a pivotal role in forming biological membranes.
Step-by-step explanation:
The molecule that has a hydrophilic head and two hydrophobic tails is known as a phospholipid. This structure is crucial for the formation of biological membranes.
The hydrophilic head group of a phospholipid contains a phosphate group attached to a glycerol molecule, which can form hydrogen bonds with water due to its polar nature or negative charge.
Conversely, the hydrophobic tails, made up of fatty acid chains, repel water as they are uncharged or non-polar. Thus, phospholipids are described as amphipathic or 'dual-loving', as they have both a portion that loves water (hydrophilic) and a portion that fears water (hydrophobic).
In biological membranes, phospholipids arrange themselves into a bilayer, where the hydrophobic tails face inwards away from water, and the hydrophilic heads face outwards towards the water.