Bacteria such as rhizobium and certain blue-green algae present in the soil can fix atmospheric nitrogen and convert into usable nitrogenous compounds, which are used by plants for the synthesis of plant proteins and other compounds.
| List-I (Function) | List-II (Organism) |
| (A) Nitrogen fixation (bacterium) | (I) Saccharomyces |
| (B) Phosphorous absorption | (II) Azospirillum |
| (C) Nitrogen fixation (cyanobacterium) | (III) Glomus |
| (D) Ethanol Production | (IV) Oscillatoria |