Biosynthetic reaction taking place in the stroma, responsible for fixing CO2 and synthesis of sugars needs

Options

A. `NADPH_(2)`
B. ATP
C. Both (1) and (2)
D. none of these

Answer

### Step-by-Step Solution:

1. **Understanding the Context**: The question refers to biosynthetic reactions in the stroma of chloroplasts, specifically focusing on the fixation of CO2 and the synthesis of sugars.

2. **Identifying the Location**: The stroma is the fluid-filled space in chloroplasts where the Calvin cycle (also known as the dark reactions) occurs. This is distinct from the thylakoid membranes where light reactions take place.

3. **Distinguishing Between Light and Dark Reactions**:
- **Light Reactions**: These occur in the thylakoid membranes and require light energy to produce ATP and NADPH.
- **Dark Reactions (Calvin Cycle)**: These occur in the stroma and do not require light directly. Instead, they utilize the ATP and NADPH produced in the light reactions to fix CO2 and synthesize sugars.

4. **Role of ATP and NADPH**:
- ATP provides the energy required for the biochemical reactions in the Calvin cycle.
- NADPH serves as a reducing agent, providing the necessary electrons for the reduction of 3-phosphoglycerate to glyceraldehyde-3-phosphate, which is a precursor for glucose and other carbohydrates.

5. **Conclusion**: The biosynthetic reactions in the stroma that fix CO2 and synthesize sugars require both ATP and NADPH produced during the light reactions.

### Final Answer:
The biosynthetic reactions taking place in the stroma, responsible for fixing CO2 and synthesizing sugars, require both ATP and NADPH.

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