If two fatty acids, glycerol, and a phosphate group undergo a dehydration reaction, what molecule forms

A Phospholipid is formed.

Explanation:

The reaction of fatty acids, glycerol and phosphoric acid is given below. In this reaction the carboxylic groups of fatty acids and the hydrogyl groups of glycerol undergo an Esterification Reaction with the elimination of two water molecules and formation of Ester functional group. Also, the third hydroxyl group of glycerol undergo dehydration reaction with phosphoric acid. The resulting molecule is known as phospholipid.

Biologically, Phospholipids are found in the cell membranes. The long hydrocarbon chains of fatty acids acts as hydrophobic (water fearing) tails and the phosphate group acts as hydrophilic (water loving) head. They form a barrier protecting the internal environment of cell from external surrounding.