disaccharide, and the main form in which carbohydrates are transported in plants . It is composed of one D-glucose molecule and one D-fructose molecule. The systematic name for sucrose, O -α-D-glucopyranosyl-(1→2)-D-fructofuranoside, indicates four things: Its monosaccharides: glucose and fructose Their ring types: glucose is a pyranose , and fructose is a furanose