plasma membranes

Your friend has isolated plasma membranes and reassembled the membranes into small vesicles. Using fluorescently labeled lectin, he sees that some of his vesicles are fluorescently labeled and some are not. Recall that lectin binds to carbohydrates. Furthermore, his labeled lectin cannot permeate membranes.
A. Which population of vesicles has a surface similar to that of the cell? Why?
B. How do you explain the other population of vesicles?