| Total estimated species on Earth | ~8.7 million | Context for need of classification |
| Kingdoms in Whittaker's system | 5 | Monera, Protista, Fungi, Plantae, Animalia |
| Year of Whittaker's classification | 1969 | Discovery date question |
| Criteria for Whittaker's classification | 5 | Cell structure, body org., nutrition, reproduction, phylogenetics |
| Size of viruses | 20–300 nm | Comparison with viroids/prions |
| Discovery of TMV by Ivanowsky | 1892 | Historical sequence question |
| Discovery of viroids by T.O. Diener | 1971 | Viroid discoverer |
| Discovery of prions by Prusiner | 1982 | Prion discoverer |
| Gram-positive cell wall | Thick peptidoglycan layer | Retains crystal violet stain |
| Gram-negative cell wall | Thin peptidoglycan + outer lipopolysaccharide (LPS) layer | Does NOT retain crystal violet |
| Diatomaceous earth composition | SiO2 (silica) frustules of dead diatoms | Uses: filtration, polishing, insulation |
| Fungi energy storage molecule | Glycogen (NOT starch) | Classic NEET trap |
| Fungi cell wall composition | Chitin (N-acetylglucosamine) | Distinguishes from plants (cellulose) |
| Lichen sensitivity gas | SO2 (sulphur dioxide) | Bioindicator of air pollution |
| Lichen forms | Crustose, Foliose, Fruticose | Morphological types |
| Phycobiont in lichen | Algal partner (photosynthetic) | Provides nutrition |
| Mycobiont in lichen | Fungal partner | Absorbs water and minerals |
| Heterocyst function | N2 fixation (anaerobic microenvironment) | In Nostoc, Anabaena |
| Enzyme for N2 fixation | Nitrogenase | Requires anaerobic conditions |
| Mycoplasma wall | Absent (no cell wall) | Smallest living cell |
| Smallest infectious agent | Viroid (naked RNA, no protein) | Smaller than viruses |
| Bacteriophage nucleic acid | DNA | Icosahedral head + tail |
| TMV nucleic acid | RNA | Helical protein coat, rod-shaped |
| HIV nucleic acid | RNA | Retrovirus |
| Coenocytic mycelium class | Phycomycetes | Aseptate hyphae |
| Plasmodium (slime mould vs protozoan) | Two different organisms — both exist | Slime mould = Physarum; Malaria = Plasmodium (protozoan) |