DAT Bootcamp Molecules and Fundamentals of Biology Practice Test

Condensation reactions, or dehydration synthesis, link two molecules by removing a water molecule. The missing water allows the atoms to share electrons and form a covalent bond, creating a larger molecule. This is why the best description is water leaving and a covalent bond forming. In biology you see this when amino acids form peptide bonds, sugars form glycosidic bonds, or fatty acids form ester bonds, each releasing water. If water were added, you’d be describing hydrolysis, which breaks bonds rather than forming them, and ionic bonds aren’t the typical product of these linking steps.