Monosaccharide- one sugar, glucose, fructose, Disaccharides- 2 monosaccharides sucrose, lactase, polysaccharides- many monosaccharides , cellulose, glycogen What carbohydrates are among the most abundant organic molecules on earth? Cellulose What types of modified carbohydrates have important biological functions? Glycogen? What are lipids and what major groups exist?