In electron transport system a carrier holds electron at

Options

A. Higher energy level than the previous carrier
B. Lower energy level than the perivous carrier
C. Same energy level as the adjacent ones
D. Initially holds it at higher level but the electron loses energy during its contact with carrier.

Answer

### Step-by-Step Solution:

1. **Understanding the Electron Transport Chain (ETC)**: The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. It plays a crucial role in cellular respiration by transferring electrons derived from nutrients to oxygen, ultimately leading to the production of ATP.

2. **Role of Electron Carriers**: In the ETC, electrons are transferred from one carrier to another. These carriers include various protein complexes (Complex I, II, III, and IV) and mobile electron carriers like ubiquinone and cytochrome c.

3. **Energy Levels of Electrons**: When electrons are transferred between these carriers, they initially hold a higher energy level. However, as they move through the chain, they lose energy. This energy loss occurs because the electrons are used to pump protons (H+) across the mitochondrial membrane, creating a proton gradient.

4. **Comparison of Energy Levels**: As the electrons move from one carrier to the next, each subsequent carrier holds the electrons at a lower energy level than the previous one. This is due to the energy being released and utilized for ATP synthesis.

5. **Conclusion**: Therefore, in the electron transport system, a carrier holds electrons at a lower energy level than the previous carrier.

### Final Answer:
In the electron transport system, a carrier holds electrons at a lower energy level than the previous carrier.

---