When does the Calvin Cycle occur in photosynthesis?

The Calvin Cycle occurs primarily during the light-independent reactions of photosynthesis, which take place in the stroma of chloroplasts. The proper understanding of when the Calvin Cycle occurs hinges on the processes involved in photosynthesis.

The cycle itself is responsible for fixing carbon dioxide (CO2) into organic molecules, thus synthesizing glucose. Therefore, it is most accurately described by the answer that refers to carbon fixation from CO2 to glucose. This is a key aspect of the Calvin Cycle, as it incorporates CO2 into a stable form, ultimately leading to the production of carbohydrates.

The incorrect choice involves the process of breaking down carbon or refers to light absorption. While light absorption does initiate the photosynthesis process and is crucial for the light-dependent reactions, it does not directly describe what occurs in the Calvin Cycle itself. The focus of the cycle is on the conversion of fixed carbon into glucose, making the accurate description essential for understanding the cycle's purpose in the photosynthetic process.