The energy from electron transport is utilized in transporting proton `(H^+)` from

Options

A. (a) matrix to outside
B. (b) outside to matrix
C. (c) in both directions
D. (d) none of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the direction in which protons (H⁺ ions) are transported using the energy derived from the electron transport chain during cellular respiration.

2. **Electron Transport Chain (ETC)**: The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. As electrons are transferred through these complexes, energy is released.

3. **Proton Transport**: The energy released during the electron transport is utilized to pump protons from one side of the mitochondrial membrane to the other. Specifically, protons are transported from the mitochondrial matrix to the intermembrane space (the space between the inner and outer mitochondrial membranes).

4. **Concentration Gradient**: This transport creates a proton gradient, where there is a higher concentration of protons in the intermembrane space compared to the matrix. This gradient is crucial for ATP synthesis.

5. **ATP Synthesis**: The protons then flow back into the matrix through ATP synthase, a process that drives the conversion of ADP and inorganic phosphate (Pi) into ATP. This process is known as chemiosmosis.

6. **Final Answer**: Therefore, the energy from the electron transport chain is utilized in transporting protons from the mitochondrial matrix to the intermembrane space (outside).

**Conclusion**: The correct answer is that the energy is used to transport protons from the matrix to the outside (intermembrane space).

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