Which of the following is NOT a type of macromolecule?

Glucose is not considered a type of macromolecule; it is classified as a simple sugar or monosaccharide. Macromolecules are typically large and complex molecules made up of smaller units called monomers. The four main types of macromolecules in biological systems are proteins, nucleic acids (like DNA and RNA), carbohydrates (where glucose falls as a building block), and lipids.

Proteins are composed of amino acids linked by peptide bonds and serve various functions, including as enzymes and structural components. Nucleic acids consist of nucleotide monomers and are essential for storing and transmitting genetic information. Lipids are hydrophobic molecules that play roles in energy storage, membrane structure, and signaling.

In contrast, glucose, as a monosaccharide, is a small molecule that serves as an energy source and building block for larger carbohydrates, such as starch and glycogen. Since glucose does not meet the criteria of being a large, complex macromolecule, it is appropriately identified as the answer in this question.