Electron transport chain is associated with

Options

A. Photosynthesis
B. Protein synthesis
C. Respiration
D. both a and c

Answer

**Step-by-Step Solution:**

1. **Understanding the Electron Transport Chain (ETC):**
The electron transport chain is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions. This process is crucial for ATP production in both cellular respiration and photosynthesis.

2. **Association with Phosphorylation:**
The primary role of the ETC is to facilitate phosphorylation, specifically the formation of ATP. This process occurs when energy released from electrons is used to pump protons (H+ ions) across a membrane, creating a proton gradient.

3. **ETC in Photosynthesis:**
In photosynthesis, the ETC is involved in photophosphorylation, which occurs in the thylakoid membranes of chloroplasts. Light energy is used to drive the transport of electrons, which ultimately leads to ATP synthesis.

4. **ETC in Cellular Respiration:**
In cellular respiration, the ETC occurs in the inner mitochondrial membrane (cristae). Here, electrons derived from metabolic substrates are transferred through the chain, leading to the pumping of protons and the synthesis of ATP via oxidative phosphorylation.

5. **Conclusion:**
The electron transport chain is associated with both photosynthesis (photophosphorylation) and cellular respiration (oxidative phosphorylation). Therefore, the correct answer to the question is that the ETC is associated with both processes.

**Final Answer:**
The electron transport chain is associated with both photosynthesis and cellular respiration.

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