Which of the following statements is incorrect?

Options

A. Copper is required in leghaemoglobin synthesis
B. Cobalt is important for plants capable of fixing molecular nitrogen
C. Molybdenum functions as an electron acceptor and a donor in the reduction of nitrogen to ammonia
D. Blue-green algae are not important for nitrogen fixation

Answer

To determine which statement is incorrect regarding mineral nutrition, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Copper is required in leg hemoglobin synthesis.**
- Leg hemoglobin is similar to hemoglobin found in human blood and is crucial for oxygen transport in leguminous plants. Copper, along with iron, is essential for the synthesis of leg hemoglobin.
- **Conclusion:** This statement is **true**.

2. **Statement 2: Cobalt is important for plants.**
- Cobalt is a micronutrient that plays a vital role in the nitrogen-fixing process in certain plants, particularly those capable of fixing molecular nitrogen. It is essential for the functioning of nitrogenase, the enzyme involved in nitrogen fixation.
- **Conclusion:** This statement is **true**.

3. **Statement 3: Molybdenum functions as an electron acceptor and donor in the reduction of nitrogen into ammonia.**
- Molybdenum is another essential micronutrient that is crucial for nitrogen fixation. It acts as a cofactor for nitrogenase, facilitating the conversion of nitrogen gas to ammonia. It indeed functions as an electron acceptor and donor in this process.
- **Conclusion:** This statement is **true**.

4. **Statement 4: Glucan and algae are not important for nitrogen fixation.**
- This statement is incorrect. Blue-green algae (cyanobacteria) such as Anabaena and Nostoc are significant contributors to nitrogen fixation in aquatic and terrestrial ecosystems. They can fix atmospheric nitrogen and are essential for maintaining soil fertility.
- **Conclusion:** This statement is **false**.

### Final Answer:
The incorrect statement is **Statement 4**.

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