Glucose and fructose are examples of isomer.
Step-by-step explanation:
The isomers are molecules that have the same molecular formula but different functional groups.
The glucose is the simplest form of carbohydrate (monosaccharide) to be taken up by the cells of the body. The glucose is an aldehyde/ aldose sugar as it contains CHO functional group.
The fructose is also a monosaccharide but it is a ketone/ ketose sugar as it has c=o functional groups.