Which one of the following statements about photosynthesis is not true ?

Options

A. All green plants photosynthesize
B. Only green plants photosynthesize
C. Carbon dioxide is reduced during photosynthesis
D. Some bacteria also photosynthesize

Answer

To determine which statement about photosynthesis is not true, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Evaluate Statement A: "All green plants photosynthesize."**
- This statement is true. Green plants contain chlorophyll, which allows them to capture light energy and convert it into chemical energy through photosynthesis.

2. **Evaluate Statement B: "Only green plants photosynthesize."**
- This statement is false. While green plants do photosynthesize, they are not the only organisms that can perform photosynthesis. Certain bacteria, such as cyanobacteria (blue-green algae), also have the ability to photosynthesize.

3. **Evaluate Statement C: "Carbon dioxide is reduced during photosynthesis."**
- This statement is true. During photosynthesis, carbon dioxide (CO2) is reduced to form glucose (C6H12O6) in the Calvin cycle.

4. **Evaluate Statement D: "Some bacteria also photosynthesize."**
- This statement is true. Certain bacteria, including cyanobacteria, are capable of photosynthesis, similar to green plants.

### Conclusion:
After evaluating all the statements, the one that is not true is **Statement B: "Only green plants photosynthesize."**

### Final Answer:
The statement that is not true is **B. Only green plants photosynthesize.**

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