Which class of biomolecules includes enzymes and antibodies?

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

Answer: (B)

Proteins are the biomolecules that include enzymes and antibodies. Enzymes are proteins that act as catalysts, speeding up chemical reactions by providing an active site where substrates bind and are converted to products. Antibodies are proteins produced by the immune system that recognize and bind to specific antigens to help defend the body. The function of proteins hinges on their amino acid sequences and the way they fold into precise three-dimensional shapes, which create the specific active or binding sites these molecules rely on. While other classes have important roles—lipids in membranes and energy storage, nucleic acids in storing and transmitting genetic information, and carbohydrates in energy and structure—the distinctive catalytic and immune functions described here come from proteins, making this the best choice.