Error 1 — Swiss cheese holes attributed to Lactobacillus Lactobacillus makes curd, not cheese holes. Swiss cheese holes are made by Propionibacterium shermanii releasing CO2 during ripening.

Error 2 — Streptokinase classified as an antibiotic Streptokinase is an enzyme (thrombolytic agent), not an antibiotic. It comes from Streptococcus and dissolves blood clots. The "strepto-" prefix tricks students into linking it to antibiotics from Streptomyces.

Error 3 — Mycorrhiza assumed to fix nitrogen Mycorrhiza (Glomus) does not fix nitrogen. Its primary benefit is enhanced phosphorus absorption. Nitrogen fixation in biofertilizers is performed by Rhizobium (symbiotic), Azotobacter/Azospirillum (free-living), and cyanobacteria.

Error 4 — Reversing the BOD-pollution relationship High BOD means more organic pollution (more oxygen consumed to decompose the organic matter). Students sometimes select "low BOD = more polluted," inverting the correct relationship.

Error 5 — Confusing Penicillium species Penicillium notatum is Fleming's antibiotic source. Penicillium roqueforti makes Roquefort cheese. These are different species with very different products.

Error 6 — Placing cyanobacteria in the wrong crop context Anabaena and Nostoc are important in paddy (rice) fields, not legume fields. Rhizobium is the legume nitrogen fixer.

Error 7 — Cyclosporin A source confusion Cyclosporin A comes from Trichoderma polysporum (a fungus). Trichoderma is also known as a biocontrol agent against soil pathogens — students must recognize its dual role.

Error 8 — Statin source Lovastatin (statin) is produced by Monascus purpureus, a fungus. Aspergillus niger is associated with citric acid, not statins.