If there are 12 molecules of `CO_(2)` to be fixed in photosynthesis, then how many turns of Calvin cycle and how many molecules of glucose will be synthesized respectively?

Options

A. 9 turns, 2 molecules
B. 12 turns, 1 molecule
C. 6 turns, 1 molecule
D. 12 turns, 2 molecules

Answer

To solve the problem, we need to determine how many turns of the Calvin cycle are required to fix 12 molecules of carbon dioxide (CO₂) and how many molecules of glucose will be synthesized from this process.

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**:
- The Calvin cycle is the process in photosynthesis where carbon dioxide is fixed into organic molecules.
- It takes one turn of the Calvin cycle to fix one molecule of CO₂.

2. **Calculating the Number of Turns**:
- If we need to fix 12 molecules of CO₂, and each turn of the Calvin cycle fixes one molecule, then:
\[ \text{Number of turns} = \text{Number of CO₂ molecules} = 12 \]
- Therefore, **12 turns of the Calvin cycle** are required.

3. **Calculating the Number of Glucose Molecules Synthesized**:
- According to the photosynthesis process, 6 molecules of CO₂ are required to synthesize 1 molecule of glucose (C₆H₁₂O₆).
- To find out how many glucose molecules can be synthesized from 12 CO₂ molecules, we can set up the following ratio:
\[ \text{Glucose molecules} = \frac{\text{Number of CO₂ molecules}}{6} = \frac{12}{6} = 2 \]
- Therefore, **2 molecules of glucose** will be synthesized.

### Final Answer:
- The number of turns of the Calvin cycle required is **12**.
- The number of glucose molecules synthesized is **2**.

### Summary:
- **12 turns of the Calvin cycle** will synthesize **2 molecules of glucose**.