Assimilatory power required to produce one molecule of glucose through `C_3` cycle in `C_3` plants is

Options

A. 6 ATP & 9 NADPH
B. 30 ATP & 18 NADPH
C. 18 NADPH & 12 ATP
D. 18 ATP & 12 NADPH

Answer

To determine the assimilatory power required to produce one molecule of glucose through the C3 cycle (Calvin cycle) in C3 plants, we need to analyze the process step by step.

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**:
- The Calvin cycle, also known as the C3 cycle, is a series of biochemical reactions that occur in the stroma of chloroplasts in C3 plants. It is responsible for the fixation of carbon dioxide (CO2) and the synthesis of glucose.

2. **Carbon Fixation**:
- In the Calvin cycle, three molecules of CO2 are fixed to form three molecules of 3-phosphoglycerate (3-PGA).

3. **Formation of G3P**:
- The 3-PGA molecules are then converted into glyceraldehyde-3-phosphate (G3P) using energy from ATP and reducing power from NADPH.

4. **Production of Glucose**:
- To produce one molecule of glucose, two molecules of G3P are required. Therefore, two turns of the Calvin cycle are necessary to yield one glucose molecule.

5. **Energy Requirements**:
- For each turn of the Calvin cycle:
- **ATP Usage**: 9 ATP molecules are used (6 ATP for the reduction phase and 3 ATP for the regeneration phase).
- **NADPH Usage**: 6 NADPH molecules are used for the reduction of 3-PGA to G3P.
- Since two turns of the cycle are needed to produce one glucose molecule, we multiply the ATP and NADPH requirements by 2.

6. **Total Energy Calculation**:
- For two turns of the Calvin cycle:
- Total ATP required = 9 ATP x 2 = 18 ATP
- Total NADPH required = 6 NADPH x 2 = 12 NADPH

7. **Final Answer**:
- Thus, the assimilatory power required to produce one molecule of glucose through the C3 cycle in C3 plants is **18 ATP and 12 NADPH**.

### Summary:
- To produce one molecule of glucose in C3 plants via the Calvin cycle, **18 ATP and 12 NADPH** are required.