Select an incorrect statement for `C_(3)` cycle

Options

A. ATP and `NADPH_(2)` are utilised
B. With the reduction of PGA, glyceraldehyde 3-phosphate is formed
C. Triose phosphates act as precursors for the synthesis of sucrose and starch
D. The regeneration of RuBP from glyceraldehyde-3-phosphate requires no ATP molecule

Answer

To answer the question "Select an incorrect statement for the C3 cycle," we will analyze each statement related to the C3 cycle (also known as the Calvin cycle) and identify which one is incorrect.

### Step-by-Step Solution:

1. **Understanding the C3 Cycle**: The C3 cycle, or Calvin cycle, is a process that occurs in plants during photosynthesis. It involves the fixation of carbon dioxide (CO2) and the conversion of this CO2 into glucose using energy from ATP and NADPH.

2. **Identifying Key Components**:
- **Ribulose bisphosphate (RuBP)**: A 5-carbon compound that reacts with CO2.
- **Phosphoglyceric Acid (PGA)**: A 3-carbon compound formed after the carboxylation of RuBP.
- **Glyceraldehyde-3-phosphate (G3P)**: A 3-carbon compound formed from PGA, which can be used to form glucose and other carbohydrates.
- **ATP and NADPH**: Energy carriers that are used in the reduction phase of the cycle.

3. **Analyzing Each Statement**:
- **Statement 1**: "ATP and NADPH2 are utilized."
- This statement is **correct** as both ATP and NADPH are used in the reduction phase of the cycle.

- **Statement 2**: "With the reduction of PGA, glyceraldehyde-3-phosphate is formed."
- This statement is also **correct** since G3P is indeed formed from the reduction of PGA.

- **Statement 3**: "Triose phosphate acts as a precursor for synthesis of sucrose and starch."
- This statement is **correct** as triose phosphate (G3P) is a precursor for the synthesis of sugars like sucrose and starch.

- **Statement 4**: "Regeneration of RuBP from glyceraldehyde 3-phosphate requires no ATP molecule."
- This statement is **incorrect** because the regeneration of RuBP from G3P does require ATP.

4. **Conclusion**: The incorrect statement regarding the C3 cycle is that the regeneration of RuBP from glyceraldehyde 3-phosphate requires no ATP molecule. Therefore, the answer is **Statement 4**.

### Final Answer:
The incorrect statement for the C3 cycle is: "Regeneration of RuBP from glyceraldehyde 3-phosphate requires no ATP molecule."