Final answer:
Photosynthesis reactions occur in the chloroplasts of autotrophs. The light-dependent reactions happen in the thylakoids, while the light-independent reactions occur in the stroma.
Step-by-step explanation:
The reactions of photosynthesis take place in the chloroplasts of autotrophs. Inside the chloroplasts, there are structures called thylakoids where the light-dependent reactions occur. The light-independent reactions, also known as the Calvin Cycle, take place in the stroma of the chloroplasts.
Learn more about Photosynthesis in autotrophs