Carbon dioxide is fixed in

Options

A. Light reaction
B. Dark reaction
C. Aerobic respiration
D. Anaerobuc respiration.

Answer

### Step-by-Step Solution:

1. **Understanding Photosynthesis**: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. This process occurs primarily in the chloroplasts of plant cells.

2. **Role of Carbon Dioxide**: Carbon dioxide (CO2) is one of the key reactants in photosynthesis. It is absorbed from the atmosphere through small openings in the leaves called stomata.

3. **Photosynthesis Stages**: Photosynthesis consists of two main stages: the light-dependent reactions and the light-independent reactions (also known as the dark reactions or Calvin cycle).

4. **Dark Reactions**: The dark reactions do not require light directly. They occur in the stroma of the chloroplasts, where CO2 is fixed into organic molecules. This process uses the energy and electrons provided by ATP and NADPH, which are generated during the light-dependent reactions.

5. **Calvin Cycle**: The specific pathway through which carbon dioxide is fixed during the dark reactions is known as the Calvin-Benson cycle. In this cycle, CO2 is converted into glucose through a series of enzymatic reactions.

6. **Conclusion**: Therefore, carbon dioxide is fixed during the dark reactions of photosynthesis, specifically in the Calvin-Benson cycle.

### Final Answer:
Carbon dioxide is fixed in the dark reactions of photosynthesis, specifically in the Calvin-Benson cycle.

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