Which term refers to the thick fluid inside a chloroplast where the light-independent reactions take place?

The term that refers to the thick fluid inside a chloroplast where the light-independent reactions, also known as the Calvin cycle, take place is "stroma." The stroma is the aqueous matrix that surrounds the thylakoids, which are the membrane-bound structures involved in the light-dependent reactions of photosynthesis. Within the stroma, the necessary enzymes and substrates exist to facilitate the conversion of carbon dioxide and ribulose bisphosphate into glucose and other sugars during the light-independent reactions. This process does not require light directly but relies on the products generated from the light-dependent reactions, showcasing the interdependent nature of these two phases of photosynthesis.

The other options refer to different components of the chloroplast. The term "matrix" is typically used in the context of mitochondria, describing the space within those organelles. "Granum" refers to the stacks of thylakoids where light-dependent reactions occur, while "thylakoid" is the individual membrane-bound sac that contains chlorophyll and is crucial for capturing light energy. Understanding these distinctions highlights the crucial role of the stroma in photosynthesis and its function in organic molecule synthesis.