RuBisCO is

Options

A. RuBP carboxylase
B. RuBP oxygenase
C. RuBP carboxylase-oxygenase
D. RuBP carboxydismutase.

Explanation

**Step-by-Step Solution:**

1. **Understanding RuBisCO**: RuBisCO is an enzyme that plays a crucial role in the process of photosynthesis, specifically in the Calvin cycle. It is responsible for the fixation of carbon dioxide.

2. **Full Form of RuBisCO**: The full name of RuBisCO is Ribulose-1,5-bisphosphate carboxylase/oxygenase. This indicates that it has dual functions: it can act as a carboxylase (fixing carbon dioxide) and as an oxygenase (involved in photorespiration).

3. **Function in Photosynthesis**: RuBisCO catalyzes the first major step of carbon fixation in the Calvin cycle, where it combines carbon dioxide with ribulose-1,5-bisphosphate (RuBP) to form 3-phosphoglycerate (3-PGA).

4. **Importance in Photorespiration**: In addition to its carboxylase activity, RuBisCO can also react with oxygen instead of carbon dioxide, leading to a process called photorespiration, which can reduce the efficiency of photosynthesis.

5. **Conclusion**: Based on the functions and characteristics of RuBisCO, the correct answer to the question is that RuBisCO stands for Ribulose-1,5-bisphosphate carboxylase/oxygenase.

**Final Answer**: RuBisCO is Ribulose-1,5-bisphosphate carboxylase/oxygenase.

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