Class 12 NEET Biology Microbes in Human Welfare

(a) : The most common symbiotic association of legume and bacteria on roots is as nodules, which are small outgrowth on the roots. The microbe Frankia is symbiont in root nodules of several non-legume plants like Casurina and Alnus. Both Rhizobium and Frankia are free living in soil but as symbiont can fix atmospheric nitrogen.