Select the wrong statement

Options

A. One Calvin cycle needed to form one glucose molecule
B. Reduction of one molecule of `CO_(2)` to carbohydrate requires a minimum of 4 quanta of light
C. Reduction of `NADP""^(+)` to NADPH takes place during Calvin's cycle
D. All are wrong

Answer

To solve the question of selecting the wrong statement regarding the Calvin cycle and photosynthesis, we will analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** One Calvin cycle is needed to form one glucose molecule.

- **Explanation:** The Calvin cycle fixes one molecule of carbon dioxide (CO2) per cycle. Since glucose (C6H12O6) contains six carbon atoms, it requires six molecules of CO2 to form one glucose molecule. Therefore, it takes **six Calvin cycles** to produce one glucose molecule.
- **Conclusion:** This statement is **incorrect**.

### Step 2: Analyze the Second Statement
**Statement:** Reduction of one molecule of carbon dioxide to carbohydrate requires a minimum of 4 quanta of light.

- **Explanation:** Research by Emerson shows that it actually takes **eight quanta of light** to reduce one molecule of carbon dioxide to carbohydrate. Therefore, stating that only four quanta are required is incorrect.
- **Conclusion:** This statement is also **incorrect**.

### Step 3: Analyze the Third Statement
**Statement:** Reduction of NADP+ to NADPH takes place during the Calvin cycle.

- **Explanation:** The reduction of NADP+ to NADPH occurs during the **light reactions** of photosynthesis, specifically during non-cyclic photophosphorylation. The Calvin cycle itself does not produce NADPH; it uses NADPH produced in the light reactions.
- **Conclusion:** This statement is **incorrect**.

### Step 4: Analyze the Fourth Statement
**Statement:** All are wrong.

- **Explanation:** Since all the previous statements have been determined to be incorrect, this statement is indeed correct.
- **Conclusion:** This statement is **correct**.

### Final Answer
The wrong statement is the first, second, and third statements. Therefore, the correct answer is **the fourth option: all of these statements are wrong**.

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