Final answer:
The stroma of chloroplasts contains the necessary enzymes for assembling organic molecules from carbon dioxide, a crucial step in photosynthesis following light reactions.
Step-by-step explanation:
The chloroplasts contain enzymes needed to assemble organic molecules from CO2 primarily within an area known as the stroma. The stroma is a gel-like fluid that fills the space between the inner membrane of a chloroplast and the thylakoid system.
Here, in this fluid-filled space, the Calvin cycle takes place, utilizing the enzymes present to convert carbon dioxide (CO2) into glucose and other organic molecules as part of the process of photosynthesis. This process occurs after the initial light reactions, which happen in the thylakoids where the chlorophyll is located, capture light energy.