Which of the following accurately describes the role of Rubisco in photosynthesis?

Rubisco, or ribulose bisphosphate carboxylase/oxygenase, plays a crucial role in the process of photosynthesis by catalyzing the primary reaction in the Calvin Cycle. This enzyme facilitates the reaction between carbon dioxide and ribulose-1,5-bisphosphate (RuBP), which ultimately leads to the fixation of carbon and the formation of carbohydrates.

In this reaction, Rubisco binds carbon dioxide to RuBP, resulting in the production of an unstable six-carbon intermediate that quickly breaks down into two molecules of 3-phosphoglycerate (3-PGA). This step is essential because it is the first major step of the carbon fixation process, which allows plants to convert atmospheric carbon dioxide into organic molecules, contributing significantly to the overall process of photosynthesis.

The other options relate to functions that do not involve Rubisco. The transport of water is primarily conducted through the plant's vascular system, light absorption is carried out by chlorophyll, and while chlorophyll is vital for capturing light energy, it is not synthesized by Rubisco.