In photosynthesis, 12 molecules of water are utilised and 6 molecules of water are released while the formation of one molecule of glucose.
The oxygen atom present in glucose came from

Options

A. the fixed carbon dioxide
B. the water released
C. the water utilised
D. Both (A) & (C)

Answer

To solve the question regarding the source of the oxygen atom present in glucose during photosynthesis, we can break down the process 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. The overall equation for photosynthesis can be summarized as:
\[ 6 \text{CO}_2 + 6 \text{H}_2\text{O} \xrightarrow{\text{light}} \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2 \]
This means that six molecules of carbon dioxide (CO2) and six molecules of water (H2O) are used to produce one molecule of glucose (C6H12O6) and six molecules of oxygen (O2).

2. **Analyzing Water Utilization**: In the question, it is stated that 12 molecules of water are utilized and 6 molecules of water are released. This indicates that during the process of photosynthesis, water is both consumed and produced.

3. **Identifying the Source of Oxygen in Glucose**: The question specifically asks where the oxygen atom in glucose comes from.
- During photosynthesis, carbon dioxide (CO2) is reduced to form glucose.
- The oxygen atoms in glucose (C6H12O6) come from the carbon dioxide that is fixed during the process.

4. **Conclusion**: Therefore, the oxygen atoms present in glucose originate from the carbon dioxide (CO2) that is utilized in photosynthesis. The hydrogen atoms in glucose come from the water (H2O) that is used.

### Final Answer:
The oxygen atom present in glucose came from carbon dioxide (CO2).

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