Question

Which one of the following is wrong statement?

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

Answer 1

The correct option is C Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins

Phosphorus is a constituent of cell membranes as a phospholipid and in nucleic acid. Proteins are rich in phosphorus but phosphorus is not a constituent of all proteins.

Root nodule forming bacteria (Rhizobium) are free-living in soil. They usually live as aerobes under free-living conditions. But for nitrogen fixation, they develop symbiotic relations with plants and are strictly anaerobic during nitrogen fixation to activate the nitrogenase enzyme.

Anabaena and Nostoc are capable of fixing nitrogen in free-living state.

Nitrosomonas and Nitrobacter play an important role in nitrification. They are chemoautotrophs.