Photosynthesis takes place primarily inside the chloroplasts of plant cells. Chloroplasts are specialized organelles found mainly in the mesophyll cells of leaves, where most photosynthesis occurs

. Within chloroplasts, the process happens in structures called thylakoids- flattened, disc-shaped membranes that contain chlorophyll, the green pigment that captures light energy

. The thylakoid membranes are the site of the light-dependent reactions, while the surrounding fluid called the stroma is where the light-independent reactions (carbon fixation) occur

. In summary:

• Photosynthesis occurs in chloroplasts inside plant cells.
• Chloroplasts are abundant in the mesophyll layer of leaves.
• The thylakoid membranes within chloroplasts contain chlorophyll and carry out light-dependent reactions.
• The stroma of the chloroplast is where carbon fixation takes place.

Thus, photosynthesis mainly takes place in the chloroplasts of leaf mesophyll cells