Final answer:
C4 plants perform photosynthesis in both mesophyll and bundle-sheath cells, with the latter being responsible for the Calvin cycle in the C4 photosynthetic pathway.
Step-by-step explanation:
C4 plants divide photosynthesis between two types of cells: the mesophyll and the bundle-sheath cells. The mesophyll consists of the palisade parenchyma and the spongy parenchyma. Palisade parenchyma cells are tightly packed and contain numerous chloroplasts, facilitating the initial steps of photosynthesis. The spongy parenchyma, which also contains chloroplasts, facilitates gas exchange with the external atmosphere through intercellular air spaces and stomata.
Bundle-sheath cells are located surrounding the leaf veins and are also involved in the photosynthetic process, specifically in the Calvin cycle of C4 plants. These cells have chloroplasts and are essential for the C4 pathway, which concentrates CO2 to avoid the inefficiencies of photorespiration found in C3 plants.