Energy released during movement of electrons through the photosystems in photosynthesis is used to drive protons across the membrane against concentration gradient. As a result the protons accumulate in

Options

A. thylakoid lumen
B. stoma of chloroplast
C. matrix of mitochondrion
D. none of these

Answer

To answer the question regarding where the protons accumulate during photosynthesis, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding Photosynthesis**: Photosynthesis occurs in the chloroplasts of plant cells and involves two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle).

2. **Role of Photosystems**: In the light-dependent reactions, light energy is absorbed by chlorophyll in the photosystems (Photosystem I and II). This energy excites electrons, which are then transferred through a series of proteins in the thylakoid membrane.

3. **Movement of Electrons**: As the electrons move through the electron transport chain, they release energy. This energy is utilized to pump protons (H⁺ ions) from the stroma (the fluid surrounding the thylakoids) into the thylakoid lumen (the interior space of the thylakoids).

4. **Proton Accumulation**: The pumping of protons into the thylakoid lumen creates a proton gradient, where there is a higher concentration of protons inside the lumen than in the stroma.

5. **Importance of Proton Gradient**: This proton gradient is crucial for the process of photophosphorylation, where ATP is generated as protons flow back into the stroma through ATP synthase.

6. **Conclusion**: Therefore, the protons accumulate in the **thylakoid lumen** as a result of the energy released during the movement of electrons through the photosystems.

### Final Answer:
The protons accumulate in the **thylakoid lumen**.

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