Systematic names for the sugars:
Glucose: D-glucose
Fructose: D-fructose
Sucrose: α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside
Lactose: β-D-galactopyranosyl-(1→4)-D-glucose
Maltose: α-D-glucopyranosyl-(1→4)-D-glucose
The reducing end of the disaccharides are:
Sucrose: The fructose moiety is the reducing end.
Lactose: The glucose moiety is the reducing end.
Maltose: The glucose molecule at the non-1 position is the reducing end.
The configuration (α or β) of the anomeric carbon indicates whether that monosaccharide unit is in the 'up' (α) or 'down' (β) position relative to the plane of the ring structure. The reducing end of a disaccharide is the monosaccharide unit that contains a free anomeric hydroxyl group, which can undergo oxidative cleavage to release individual monosaccharide units.