what type of functional group connects fructose and glucose to make sucrose?

Answer 1

a glycosidic bond between carbon atom 1 of the glucose unit and carbon atom 2 of the fructose units.

Answer 2

Sucrose has an alpha 1,2 linkage joining glucose and fructose. These number refer to the carbon numbers around the cyclic sugars.
(That alpha should be written like the Greek letter.)

Answer 3

It is a C-O-C linkage where the "C's" are part of the ring of the two cyclic sugars. I don't know if there is a specific name for this linkage.