How many ATPs are required by `C_(4)` plants in synthesis of one molecule of glucose

Options

A. 18 ATP
B. 30 ATP
C. 12 ATP
D. None of the above.

Answer

To determine how many ATP molecules are required by C4 plants to synthesize one molecule of glucose, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding C4 Photosynthesis**:
- C4 plants utilize a unique photosynthetic pathway that includes both the C4 cycle and the C3 cycle (Calvin cycle).
- Examples of C4 plants include sugarcane and maize.

2. **Carbon Dioxide Fixation**:
- In the C4 pathway, carbon dioxide (CO2) is fixed twice: first in the C4 cycle and then in the C3 cycle.
- Each CO2 molecule requires ATP during both cycles.

3. **ATP Requirement in C4 Cycle**:
- For each CO2 molecule fixed in the C4 cycle, 2 ATP molecules are consumed.

4. **ATP Requirement in C3 Cycle**:
- For each CO2 molecule fixed in the C3 cycle, 3 ATP molecules are consumed.

5. **Total ATP for One CO2 Fixation**:
- Therefore, the total ATP required to fix one CO2 molecule is:
\[ \text{Total ATP per CO2} = \text{ATP in C4 cycle} + \text{ATP in C3 cycle} = 2 \text{ ATP} + 3 \text{ ATP} = 5 \text{ ATP} \]

6. **Glucose Synthesis**:
- To synthesize one molecule of glucose (C6H12O6), 6 CO2 molecules need to be fixed.
- Thus, the total ATP required for fixing 6 CO2 molecules is:
\[ \text{Total ATP for glucose} = 6 \text{ CO2} \times 5 \text{ ATP per CO2} = 30 \text{ ATP} \]

7. **Conclusion**:
- Therefore, the total number of ATP molecules required by C4 plants to synthesize one molecule of glucose is **30 ATP**.

### Final Answer:
30 ATP

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