Final answer:
Photosynthesis takes place within the chloroplasts, which contain thylakoids with chlorophyll, where light is captured for the light reactions. The surrounding stroma is the site of the Calvin cycle.
Step-by-step explanation:
Chloroplasts: The Site of Photosynthesis
The organelle in which photosynthesis takes place is the chloroplast. These are specific to plant cells and certain algae and are found in chloroplast-containing cells in the mesophyll of leaves. Inside the chloroplast, there is a double membrane envelope, consisting of an outer and an inner membrane. Within these membranes, are disc-shaped structures called thylakoids, where the light reactions of photosynthesis occur. The thylakoids contain chlorophyll, the green pigment responsible for capturing light energy, which is essential for starting the photosynthesis process. The thylakoid membranes are arranged in stacks known as grana. The surrounding fluid is called the stroma, where the Calvin cycle occurs. Photosynthesis is a two-part process involving the light reactions in the thylakoid membranes and the Calvin cycle in the stroma.