This document discusses biomolecules and carbohydrates. It defines biomolecules as molecules produced by living organisms, including macromolecules like proteins, polysaccharides, lipids and nucleic acids. Carbohydrates are the most abundant biomolecule and chief source of energy. There are four main types of carbohydrates - monosaccharides, disaccharides, polysaccharides and oligosaccharides. Glucose, fructose and galactose are examples of monosaccharides. Sucrose, lactose and maltose are disaccharides. Starch, glycogen and cellulose are polysaccharides. Carbohydrates provide energy to living organisms through digestion and absorption in the gastrointestinal tract.