Which of the following mechanisms best explains nitrogen fixation in legume root nodules?

Step-by-step solution

1. 1. State that nitrogen fixation in legumes occurs in root nodules.
2. 2. Explain that Rhizobium bacteria in the nodules convert atmospheric $N_2$ into ammonia.
3. 3. Indicate that this process is symbiotic and is distinct from photosynthesis and direct absorption.
4. 4. Therefore, the correct mechanism is symbiotic nitrogen fixation.

Concept tested: Nitrogen fixation mechanism

Published 13 October 2026 · How this solution was prepared and checked