The immediate product of carboxylation in `C_3` plants

Options

A. RuBP
B. PGA
C. OAA
D. GAP

Answer

### Step-by-Step Solution:

1. **Understanding Carboxylation in C3 Plants**:
- Carboxylation is the process where carbon dioxide (CO2) is fixed into an organic molecule. In C3 plants, this process occurs during photosynthesis.

2. **Identifying the Initial Substrate**:
- In C3 plants, the initial substrate for carboxylation is Ribulose 1,5-bisphosphate (RuBP), which is a 5-carbon compound.

3. **Formation of Unstable Intermediate**:
- When CO2 combines with RuBP, it forms a very unstable 6-carbon compound. This compound does not persist for long due to its instability.

4. **Splitting of the Unstable Compound**:
- The unstable 6-carbon compound immediately splits into two molecules of a 3-carbon compound.

5. **Identifying the Immediate Product**:
- The 3-carbon compound formed from this splitting is Phosphoglyceric Acid (PGA). This is the first stable product of the carboxylation process in C3 plants.

6. **Conclusion**:
- Therefore, the immediate product of carboxylation in C3 plants is Phosphoglyceric Acid (PGA).

### Final Answer:
The immediate product of carboxylation in C3 plants is **PGA (Phosphoglyceric Acid)**.

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