Final answer:
The enzyme Rubisco bonds to O₂ as part of photorespiration but mainly operates in the Calvin cycle, catalyzing the reaction between CO₂ and RuBP during the fixation stage.
Step-by-step explanation:
The Role of Rubisco in Photosynthesis
The bonding of the enzyme Rubisco to O₂ is part of the photorespiration process, where Rubisco adds oxygen to RuBP instead of carbon dioxide. However, Rubisco primarily functions in the Calvin cycle, a key component of photosynthesis. During the fixation stage of the Calvin cycle, Rubisco catalyzes the reaction between CO₂ and ribulose bisphosphate (RuBP). Each CO₂ molecule reacting with one RuBP results in two molecules of 3-phosphoglycerate (3-PGA). This process is essential for converting inorganic carbon from CO₂ into organic molecules like carbohydrates.
The Calvin cycle stages include fixation, reduction, and regeneration. In the reduction stage, ATP and NADPH from the light-dependent reactions are used to convert 3-PGA into glyceraldehyde-3-phosphate (G3P), which is then used to build glucose and regenerate RuBP, facilitating continuous CO₂ fixation.