Which process involves chemiosmotic phosphorylation?

Options

A. Krebs cycle
B. Glycolysis
C. Electron transport system
D. Fermentation

Explanation

### Step-by-Step Solution:

1. **Understanding Chemiosmosis**:
- Chemiosmosis is defined as the movement of ions across a semipermeable membrane down their electrochemical gradient. This process is crucial for energy production in cells.

2. **Mechanism of Chemiosmosis**:
- In mitochondria, protons (H⁺ ions) are pumped from the inner compartment to the outer compartment through specific membrane channels. This creates a proton gradient, where there is a higher concentration of protons outside compared to inside the mitochondria.

3. **Proton Gradient and ATP Synthesis**:
- Once the proton gradient is established, protons diffuse back into the inner compartment through a protein complex known as ATP synthase. This flow of protons down their concentration gradient provides the energy needed to synthesize ATP from ADP and inorganic phosphate.

4. **Evaluating the Options**:
- **Krebs Cycle**: This process involves a series of chemical reactions for energy release but does not involve chemiosmosis. Therefore, it is not the correct answer.
- **Glycolysis**: This process converts glucose into pyruvate and does not involve chemiosmosis either. Thus, it is incorrect.
- **Electron Transport System (ETS)**: This is the correct process that involves chemiosmotic phosphorylation. The electrochemical gradient established during the electron transport chain is utilized to generate ATP through chemiosmosis.
- **Fermentation**: This metabolic process is enzyme-driven and does not involve chemiosmosis. Hence, it is also incorrect.

5. **Conclusion**:
- The process that involves chemiosmotic phosphorylation is the **Electron Transport System (ETS)**.