Q: What are disaccharides?
Although theoretically disaccharides could be made up of two trioses, tetroses, pentoses but all naturally occurring disaccharides contain hexose molecules - either aldohexoses or ketohexoses. Because of their OH groups, the rings of monosaccharides can be joined together to form disaccharides. The reaction is a dehydration reaction between molecules forming a glycosidic bond.