Winglets aim to reduce fuel consumption by reducing drag. They do this by minimising spanwise flow from the lower surface to the upper surface of the wing which creates a vortex and alters the induced angle of attack resulting in more drag.
By "adhedral" I assume you mean anhedral. As said before, technical terms will help in a university examination. However I'm not sure winglets affect this much as the primary function is to increase the efficiency of the wing.