Final answer:
Freeze-fracture replication is the technique used to investigate the microheterogeneity of a membrane, revealing localized differences and membrane asymmetry through scanning electron microscopy.
Step-by-step explanation:
The technique that allows investigation of the microheterogeneity of a membrane to see localized differences in different parts of the membrane is freeze-fracture replication.
This technique involves freezing the membrane and then fracturing it, which tends to split the membrane along the middle of the phospholipid bilayer, revealing the asymmetrical organization. Scanning electron microscopy is then used to observe the characteristics of the interior and exterior surfaces of the membrane, enabling the detection of pits and mounds and demonstrating the asymmetry and localized differences in membrane structure.