True or False:RUBISCO only binds to CO₂.

• A. True
• B. False

Answer: (B)

Verified step by step guidance

1. Understand the role of RUBISCO: Ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) is an enzyme involved in the first major step of carbon fixation in the Calvin cycle of photosynthesis.
2. Recognize the dual function of RUBISCO: It can catalyze the reaction of ribulose-1,5-bisphosphate (RuBP) with either carbon dioxide (CO2) or oxygen (O2).
3. Identify the two reactions: When RUBISCO binds to CO2, it facilitates the carboxylation reaction, leading to the production of two molecules of 3-phosphoglycerate. When it binds to O2, it facilitates the oxygenation reaction, leading to the production of one molecule of 3-phosphoglycerate and one molecule of 2-phosphoglycolate.
4. Consider the implications of RUBISCO's dual activity: The ability to bind both CO2 and O2 means that RUBISCO is not specific to CO2 alone, which is a key point in understanding its function in photosynthesis and photorespiration.
5. Conclude the analysis: Based on the dual binding capability of RUBISCO, the statement 'RUBISCO only binds to CO2' is false, as it also binds to O2.