Final answer:
The anomeric carbon in sucrose is involved in a glycosidic bond and cannot open to form an aldehyde or ketone group, making it a non-reducing end.
Step-by-step explanation:
The term 'non-reducing end' refers to a specific carbon atom in a sugar molecule that cannot be involved in an open-chain form. In the context of sucrose, the carbon atom in question is the anomeric carbon, which is involved in the glycosidic bond connecting the two monosaccharides. The anomeric carbon in sucrose is not free and unsubstituted, which means it cannot open to form an aldehyde or ketone group, hence it is considered a non-reducing end.