Question

Which of the following organisms is a nitrogen-fixing bacterium that forms a symbiotic association with leguminous plants?

Options

• Frankia only associates with non-leguminous plants

• Rhizobium

• Anabaena

• Azolla

Answer 1

Rhizobium is a key nitrogen-fixing microorganism that forms a symbiotic association specifically with leguminous plants, leading to the formation of root nodules where nitrogen fixation occurs. While Frankia also fixes nitrogen, it associates with non-leguminous plants. Anabaena is a cyanobacterium, and Azolla is a water fern, not nitrogen-fixing bacteria themselves.