What are the organic chemical groups that characterize carbohydrates? How are carbohydrates classified according to the presence of those groups?
Carbohydrates are also called as sugars (starches, cellulose and other substances are carbohydrates too).
Carbohydrates are polyhydroxylated aldehydes or polyhydroxylated ketones (polyalcohol aldehydes or polyalcohol ketones).
Polyhydroxylated aldehydes are called aldoses and polyhydroxylated ketones are known as ketoses.