Light reaction takes place in the (A) chloroplast envelope (B) grana (C) stroma (D) cytoplasm

Options

A. chloroplast envelope
B. grana
C. stroma
D. cytoplasm

Answer

To determine where the light reaction of photosynthesis takes place, let's analyze the options provided:

1. **Understanding Light Reaction**:
- The light reaction is the first stage of photosynthesis where solar energy is converted into chemical energy. This process produces ATP and NADPH, which are essential for the subsequent stages of photosynthesis.

2. **Identifying the Location**:
- Photosynthesis occurs in chloroplasts, which are the organelles responsible for capturing light energy.
- Within the chloroplasts, there are two main components: the stroma and the thylakoids. The thylakoids are organized into stacks known as grana.

3. **Analyzing the Options**:
- (A) **Chloroplast envelope**: This is the outer structure of the chloroplast and does not participate in the light reactions.
- (B) **Grana**: This is where the thylakoids are stacked, and it is the site of the light reactions.
- (C) **Stroma**: This is the fluid-filled space surrounding the thylakoids, where the Calvin cycle (light-independent reactions) occurs, but not the light reactions.
- (D) **Cytoplasm**: This is the fluid inside the cell but outside the chloroplasts, and it does not play a role in the light reactions.

4. **Conclusion**:
- Based on the understanding that light reactions occur in the thylakoids, which are organized into grana, the correct answer is **(B) grana**.

**Final Answer**: (B) grana

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