Question: what are the four main classes of biomolecules?
Answer: Carbohydrates. Carbohydrates are comprised of the elements carbon (C), hydrogen (H), and oxygen (O). ... 
Proteins. Proteins are comprised of amino acids. ... 
Lipids. A wide variety of biomolecules including fats, oils, waxes and steroid hormones. ... 
Nucleic Acids.