Disaccharides: is one of four groups of Carbohydrates 

(monosaccharide, disaccharide, polysaccharide, 

and oligosaccharide). A disaccharide or biose is the 

carbohydrate formed when two monosaccharides undergo 

a condensation reaction, which involves the elimination of 

a small molecule, such as water, from the functional groups 

only.