How much NADPH and ATP are utilized in `C_(4)` cycle for the fixation of each `CO_(2)` molecule in mesophyll cell, respectively?

Options

A. one and two
B. two and six
C. two and eight
D. two and three

Answer

To determine how much NADPH and ATP are utilized in the C4 cycle for the fixation of each CO2 molecule in mesophyll cells, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the C4 Cycle**: The C4 cycle, also known as the Hatch and Slack pathway, is a photosynthetic process that occurs in certain plants (like maize and sugarcane). It involves the fixation of CO2 into a four-carbon compound.

2. **Carbon Fixation**: In the mesophyll cells, CO2 is initially fixed into a four-carbon compound (oxaloacetate) by the enzyme PEP carboxylase. This process requires the molecule phosphoenolpyruvate (PEP).

3. **ATP Utilization**:
- To convert pyruvate into PEP, one molecule of ATP is used.
- Additionally, during the transport of malate (the four-carbon compound) into bundle sheath cells, another ATP molecule is consumed.
- Therefore, a total of **2 ATP molecules** are utilized for the fixation of one CO2 molecule.

4. **NADPH Utilization**:
- During the conversion of oxaloacetate to malate, one molecule of NADP+ is reduced to NADPH.
- Thus, **1 NADPH molecule** is utilized in the process.

5. **Final Summary**:
- For the fixation of each CO2 molecule in mesophyll cells of C4 plants, **2 ATP** and **1 NADPH** are utilized.

### Final Answer:
- **NADPH utilized**: 1
- **ATP utilized**: 2