Monosaccharide includes fructose, galactose, ribose and deoxyribose, in which glucose is the main energy source of life activities. Fructose and galactose are components of disaccharide. Ribose and deoxyribose are components of ribonucleotides and deoxynucleotides.

Disaccharide is formed by dehydration and condensation of two monosaccharides, mainly sucrose, maltose and lactose. When eaten, disaccharide is mainly hydrolyzed into monosaccharide, which makes cells absorb and produce sweetness.

Most polysaccharides in organisms exist in the form of polysaccharides. It is also a substance that stores energy.