Final answer:
The thylakoid membrane in cyanobacteria is an infolded plasma membrane and it contains photosynthetic pigments for photosynthesis.
Step-by-step explanation:
The thylakoid membrane of the cyanobacterium is an infolded plasma membrane. In cyanobacteria, photosynthetic pigments such as chlorophyll are located within these infolded regions that enable them to perform photosynthesis. Unlike eukaryotic cells with chloroplasts, cyanobacteria do not have distinct, membrane-enclosed organelles for photosynthesis; rather, their thylakoid membranes are integrated within the cell itself as extensions of the plasma membrane.