Which class of compounds is commonly linked to essential oils and fragrances?

• A. Proteins
• B. Lipids
• C. Terpenes
• D. Nucleic acids

Answer: (C)

Terpenes are the molecules most closely tied to essential oils and fragrances. Plants build terpenes from isoprene units, and many of these compounds are volatile, meaning they evaporate easily and carry distinct scents. This volatility and diversity give essential oils their characteristic fragrances—think of citrus oils rich in limonene or pine and conifer oils with various monoterpenes and sesquiterpenes. While other biomolecule classes have important roles in biology, they aren’t the primary source of the aromatic compounds we associate with essential oils. Proteins and nucleic acids serve structural, catalytic, or genetic roles, and lipids are nonpolar and contribute to other properties, but the fragrant components of essential oils are mainly terpenes (and related terpenoids).