Final answer:
Lipids are the biological polymers defined by the physical property of being insoluble in water, unlike polysaccharides, proteins, or nucleic acids which are classified by specific chemical structures.
Step-by-step explanation:
The one biological polymer defined by a physical property rather than a chemical structure is lipids. While other biological polymers like polysaccharides, proteins, and nucleic acids have specific chemical structures defining their respective classifications, lipids are categorized based upon their physical property of being insoluble in water.
Lipids are diverse in structure and function but share this common, unifying physical characteristic. In contrast, polysaccharides such as starch and cellulose are identified by their specific glycosidic bonds, proteins by the sequence of amino acids joined by peptide bonds, and nucleic acids by their phosphate diester linkages.
The biological polymer that is defined by a physical property rather than a chemical structure is lipids.
Unlike other biological polymers such as proteins, nucleic acids, and polysaccharides which are defined by their specific chemical structures and compositions, lipids are defined by their physical property of being hydrophobic or insoluble in water.
Lipids include molecules such as fats, oils, and waxes, which serve as energy storage, insulation, and structural components in living organisms.
For example, the hydrophobic nature of lipids allows them to form cell membranes, which serve as a barrier between the cell and its external environment.