In calvin cycle, carboxylation of RuBP results in the formation of how many number of PGA molecules ?

Options

A. 2 `xx` PGA
B. 1 `xx` PGA
C. 3 `xx` PGA
D. 4 `xx` PGA

Answer

To answer the question regarding the number of PGA (3-phosphoglycerate) molecules formed during the carboxylation of RuBP (ribulose bisphosphate) in the Calvin cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding RuBP**:
- RuBP is a 5-carbon compound that plays a crucial role in the Calvin cycle.

2. **Carboxylation Reaction**:
- During the Calvin cycle, RuBP undergoes a carboxylation reaction when it combines with carbon dioxide (CO₂).

3. **Formation of a 6-Carbon Intermediate**:
- When CO₂ is added to RuBP, a 6-carbon intermediate is formed. This intermediate is unstable and quickly breaks down.

4. **Splitting of the 6-Carbon Compound**:
- The 6-carbon compound splits into two 3-carbon molecules. These molecules are known as PGA (3-phosphoglycerate).

5. **Calculating the Number of PGA Molecules**:
- Since one molecule of RuBP reacts with one molecule of CO₂ to form one 6-carbon compound, which then splits into two 3-carbon PGA molecules, the result is that two PGA molecules are formed.

### Conclusion:
- Therefore, the carboxylation of RuBP results in the formation of **2 PGA molecules**.