Electron energy is used to drive protons against concentration gradient across thylakoid membrane into

Options

A. Stroma lamella
B. Thylakoid lumen
C. Stroma
D. Interthylakoid space.

Answer

To solve the question "Electron energy is used to drive protons against concentration gradient across thylakoid membrane into", we can follow these steps:

### Step 1: Understand the Thylakoid Structure
The thylakoid is a membrane-bound structure within the chloroplasts where the light-dependent reactions of photosynthesis occur. It consists of a thylakoid membrane that encloses a space known as the thylakoid lumen.

**Hint:** Remember that the thylakoid membrane separates two distinct compartments: the thylakoid lumen inside and the stroma outside.

### Step 2: Identify the Process Involved
During the light-dependent reactions, light energy is absorbed by chlorophyll, which excites electrons. These high-energy electrons are transferred through a series of proteins in the electron transport chain located in the thylakoid membrane.

**Hint:** Focus on the role of light energy in exciting electrons and how this energy is utilized in the process.

### Step 3: Understand Proton Movement
As electrons move through the electron transport chain, their energy is used to pump protons (H⁺ ions) from the stroma into the thylakoid lumen. This movement creates a proton gradient across the thylakoid membrane.

**Hint:** Consider how the movement of protons creates a difference in concentration, leading to a potential energy difference known as the proton motive force.

### Step 4: Determine the Final Destination of Protons
The question asks where the protons are driven against their concentration gradient. Since protons are moved from the stroma (lower concentration) into the thylakoid lumen (higher concentration), the correct answer is the thylakoid lumen.

**Hint:** Visualize the flow of protons and remember that they are moving from an area of lower concentration to an area of higher concentration.

### Conclusion
Based on the understanding of the thylakoid structure, the process of electron transport, and the movement of protons, the correct answer to the question is:
**Thylakoid lumen** (Option 2).

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