Name the two important enzymes of `C_(3)` and `C_(4)` pathway, respectively. What important role do they play in fixing `CO_(2)` ?

Explanation

**Step-by-Step Solution:**

1. **Identify the Enzymes:**
- For the **C3 pathway**, the important enzyme is **RUBP carboxylase/oxygenase** (often abbreviated as RuBisCO).
- For the **C4 pathway**, the important enzyme is **phosphoenolpyruvate carboxylase** (commonly referred to as PEP carboxylase).

2. **Role of RUBP Carboxylase in C3 Pathway:**
- RUBP carboxylase catalyzes the carboxylation reaction where carbon dioxide (CO2) is fixed to ribulose bisphosphate (RuBP), a 5-carbon compound.
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