Oxygen released in photosynthesis is formed during

Options

A. Oxidative phosphorylation
B. Cyclic photophosphorylation
C. Noncyclic photophosphorylation
D. Carbon assimilation during dark reactions.

Answer

To answer the question "Oxygen released in photosynthesis is formed during," we will analyze the processes involved in photosynthesis step by step.

### 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 mainly in the chloroplasts of plant cells.

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

3. **Light Reactions**:
- The light reactions occur in the thylakoid membranes of the chloroplasts and require light. During this stage, light energy is captured and converted into chemical energy in the form of ATP and NADPH.

4. **Photolysis of Water**:
- A key event in the light reactions, specifically in the non-cyclic photophosphorylation pathway, is the photolysis of water. This process involves the splitting of water molecules (H2O) into oxygen (O2), protons (H+), and electrons (e-).
- The reaction can be summarized as:
\[ 2H_2O \rightarrow 4H^+ + 4e^- + O_2 \]
- The oxygen produced during this reaction is released as a byproduct into the atmosphere.

5. **Non-Cyclic Photophosphorylation**:
- Non-cyclic photophosphorylation is the pathway that leads to the production of both ATP and NADPH, and it is where the photolysis of water occurs, resulting in the release of oxygen.

6. **Conclusion**:
- Therefore, the oxygen released during photosynthesis is formed during the non-cyclic photophosphorylation phase of the light reactions.

### Final Answer:
The oxygen released in photosynthesis is formed during **non-cyclic photophosphorylation**.

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