Light energy is converted into chemical energy during the light-dependent phase and chemical energy is used to

Options

A. help in the photolysis of water
B. produce ATP and `NADPH_2`
C. reduce carbon dioxide to carbohydrate during the light-independent phase
D. both (a) and (b)

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis is the process by which green plants convert light energy into chemical energy. This process occurs in two main phases: the light-dependent reactions and the light-independent reactions (Calvin cycle).

2. **Light-Dependent Reactions**: In the light-dependent phase, which occurs in the thylakoid membranes of chloroplasts, light energy is absorbed by chlorophyll. This energy is used to split water molecules (photolysis), releasing oxygen and generating energy-rich molecules: ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).

3. **Chemical Energy Utilization**: The ATP and NADPH produced during the light-dependent reactions are then utilized in the light-independent reactions (Calvin cycle). These reactions do not require light and take place in the stroma of chloroplasts.

4. **Light-Independent Reactions (Calvin Cycle)**: In this phase, the chemical energy stored in ATP and NADPH is used to convert carbon dioxide (CO2) from the atmosphere into glucose (C6H12O6), a carbohydrate. This process involves a series of enzymatic reactions that reduce CO2 to form glucose.

5. **Conclusion**: Therefore, the chemical energy generated during the light-dependent phase is primarily used to reduce carbon dioxide into carbohydrates during the light-independent phase.

**Final Answer**: The chemical energy is used to reduce carbon dioxide to carbohydrate during the light-independent phase.

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