Carbohydrates are widely distributed in plants and animals. Plants produce carbohydrates from carbon dioxide and water by photosynthesis. The important carbohydrate found in plants is starch. Animals mainly depend upon plant sources for their carbohydrates. The carbohydrate stored in animals is glycogen.
Chemically carbohydrates are defined as polyhydric aldehyde or ketone or compounds which produce them on hydrolysis.
Example: Glucose, fructose, starch, cellulose, glycogen etc.