What are biofertilisers? Describe the role of bacteria, fungi and cyanobacteria as biofertilisers.

1. 1 · Define in one line. Biofertilisers are organisms that enrich the nutrient quality of the soil.
2. 2 · Bacteria. Rhizobium in root nodules of legumes fixes nitrogen; Azotobacter and Azospirillum fix nitrogen free-living in soil.
3. 3 · Fungi. Glomus forms mycorrhiza; absorbs phosphorus; gives resistance to root pathogens and tolerance to salinity and drought.
4. 4 · Cyanobacteria. Anabaena, Nostoc, Oscillatoria fix nitrogen and add organic matter; important in paddy fields.
5. 5 · Why it matters. Reduces dependence on chemical fertilisers and keeps soil healthy.

Scoring tip: Give one named example for each group. A list of names without what they do earns only half the marks.