Respiratory cycle where `NADPH_(2)` are produced is

Options

A. Calvin cycle
B. Kreb's cycle
C. EMP pathway
D. HMP shunt

Answer

To determine which respiratory cycle produces NADPH2, we can analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understand the cycles mentioned**: We need to look at the four cycles mentioned in the question: Calvin cycle, Krebs cycle, EMP pathway, and HMP shunt.

2. **Calvin Cycle**:
- The Calvin cycle is primarily involved in photosynthesis and does not produce NADH2 or NADPH2.
- **Conclusion**: The Calvin cycle does not produce NADPH2.

3. **Krebs Cycle**:
- The Krebs cycle (also known as the citric acid cycle) produces 2 NADH2, 1 FADH2, and 1 GTP molecule per cycle.
- **Conclusion**: The Krebs cycle does not produce NADPH2.

4. **EMP Pathway**:
- The EMP (Embden-Meyerhof-Parnas) pathway, which is a part of glycolysis, produces 2 NADH and 2 ATP molecules.
- **Conclusion**: The EMP pathway does not produce NADPH2.

5. **HMP Shunt**:
- The HMP shunt (Hexose Monophosphate Pathway) is known for producing NADPH2, which is crucial for biosynthetic reactions and maintaining cellular redox balance.
- **Conclusion**: The HMP shunt produces NADPH2.

6. **Final Answer**: Based on the analysis of each cycle, the respiratory cycle where NADPH2 is produced is the **HMP shunt**.