52.Non-symbiotic nitrogen fixing prokaryote is A. Rhizobium B. Nostoc C. Frankia D. Azotobacter
Option D Rhizobium is nitrogen fixing bacteria symbiont in proteinacious roots like alfa alfa, sweet clover, sweet pea. Nostoc is common symbiont in lichens, azolla and cycad roots. Frankia is symbiont in Alnus and casuarina (non leguminous) plants. Azotobactera is non symbiotic or free living bacterium. It helps in the nitrogen fixation.
