Which one of the following is wrong statement?

Options

A. Nitrosomonas and nitrobacter are chemoautotrophs
B. Anabaena and Nostoc are capable for fixing nitrogen in free living state also
C. Root nodule forming nitrogen fixers live as aerobes under free-living conditions
D. Phosphorus is a constituent of cell membranes, certain nucleic acid and all proteins

Answer

To determine which statement is incorrect, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Nitrosomonas and Nitrobacter are chemoautotrophs."
- **Analysis**: This statement is correct. Both Nitrosomonas and Nitrobacter are indeed chemoautotrophic bacteria involved in the nitrification process, converting ammonia to nitrates.

- **Statement 2**: "Anabina and Nostoc are capable of nitrogen fixing in free living state also."
- **Analysis**: This statement is also correct. Anabina and Nostoc are cyanobacteria that can fix atmospheric nitrogen both in free-living conditions and in symbiotic relationships.

- **Statement 3**: "Root nodule forming nitrogen fixer live as aerobes under free living conditions."
- **Analysis**: This statement is correct. Rhizobium, which forms root nodules with legumes, can live as aerobes when not in symbiosis.

- **Statement 4**: "Phosphorus is a constituent of cell membrane, certain nucleic acids, and proteins."
- **Analysis**: This statement is incorrect. While phosphorus is indeed a component of nucleic acids (DNA and RNA) and is found in cell membranes (as phospholipids), it is not a direct constituent of proteins. Proteins are made of amino acids, which do not contain phosphorus as a component.

2. **Conclusion**:
- The wrong statement among the options provided is **Statement 4**.

### Final Answer:
The wrong statement is: "Phosphorus is a constituent of cell membrane, certain nucleic acids, and proteins."

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