As compared to `C_(3)` plants, how many additional molecules of ATP are needed for net production of one molecule hexose sugar by `C_(4)` plants?

Options

A. 2
B. 3
C. 0
D. 12

Answer

To solve the question of how many additional molecules of ATP are needed for the net production of one molecule of hexose sugar by C4 plants as compared to C3 plants, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the ATP Requirement for C3 Plants**:
- In C3 plants, the Calvin cycle (C3 cycle) is responsible for the fixation of carbon dioxide and the production of hexose sugar.
- It is known that C3 plants require **18 ATP molecules** for the formation of one molecule of hexose sugar.

2. **Identify the ATP Requirement for C4 Plants**:
- C4 plants utilize both the C4 cycle and the C3 cycle for carbon fixation.
- For the production of one molecule of hexose sugar, C4 plants require **30 ATP molecules**.

3. **Calculate the Additional ATP Requirement**:
- To find the additional ATP needed by C4 plants compared to C3 plants, we subtract the ATP requirement of C3 plants from that of C4 plants:
\[ \text{Additional ATP} = \text{ATP for C4} - \text{ATP for C3} = 30 - 18 = 12 \]

4. **Conclusion**:
- Therefore, C4 plants need **12 additional ATP molecules** for the net production of one molecule of hexose sugar compared to C3 plants.

### Final Answer:
C4 plants require **12 additional molecules of ATP** for the net production of one molecule of hexose sugar compared to C3 plants.

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