Answer:
Must be either ether or ester.
Explanation:
The incorrect statement is that the monosaccharides must ether or esters.
The main and compulsory functional group in a monosaccharide are aldehyde and ketones.
The other statements are true
1) smallest monosaccharides are composed of three carbons: the smallest monosaccharide is glyceraldehyde.
a) aldoses and ketoses : they have either aldehyde group or ketone group
example: glucose is aldose and fructose if keotse
c) exist in many isomeric forms: there can be many arrangement on chiral carbons thus many stereoisomers are possible
e) Two monosaccharides can combine to form a disaccharide: yes for example glucose combines with fructose to give sucrose.
