Biological classification short notes neet
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biological classification NEET notes five kingdoms Whittaker monera protista fungi plantae animalia
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biological classification NEET viruses viroids lichens mycoplasma kingdom features important points
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biological classification five kingdoms viruses viroids lichens NEET important notes
Here are comprehensive Biological Classification short notes for NEET (Class 11, Chapter 2):
🧬 Biological Classification — NEET Short Notes
1. History of Classification
| Scientist | Contribution |
|---|---|
| Aristotle | First scientific attempt; plants → herbs/shrubs/trees; animals → with/without red blood |
| Linnaeus (1758) | Two Kingdom system — Plantae & Animalia |
| R.H. Whittaker (1969) | Five Kingdom Classification |
Demerits of Two Kingdom system:
- Did not distinguish prokaryotes from eukaryotes
- Placed fungi (heterotrophs) with plants
- No place for unicellular organisms like Euglena
2. Five Kingdom Classification (Whittaker)
Basis: Cell structure, body organization, mode of nutrition, reproduction, phylogenetic relationships
| Kingdom | Cell Type | Organization | Cell Wall | Nutrition |
|---|---|---|---|---|
| Monera | Prokaryotic | Unicellular | Polysaccharide + amino acid | Autotrophic / Heterotrophic |
| Protista | Eukaryotic | Unicellular | May be present | Autotrophic / Heterotrophic |
| Fungi | Eukaryotic | Multicellular | Chitin | Heterotrophic (Absorption) |
| Plantae | Eukaryotic | Multicellular | Cellulose | Autotrophic (Photosynthesis) |
| Animalia | Eukaryotic | Multicellular | Absent | Heterotrophic (Holozoic) |
3. Kingdom Monera
- Simplest, most primitive organisms
- Prokaryotic — no true nucleus, no membrane-bound organelles
- DNA present as nucleoid (naked DNA)
- Members: Bacteria, Cyanobacteria, Mycoplasma
Sub-groups:
| Group | Key Features |
|---|---|
| Archaebacteria | Live in extreme conditions (thermoacidophiles, halophiles, methanogens); cell wall lacks peptidoglycan |
| Eubacteria | True bacteria; cell wall has peptidoglycan; includes cyanobacteria |
| Mycoplasma | No cell wall; smallest living organisms; pleomorphic; cause PPLO diseases |
Bacterial shapes:
- Coccus (spherical), Bacillus (rod), Vibrio (comma), Spirillum (spiral)
Bacterial nutrition:
- Autotrophs: Photosynthetic (e.g., cyanobacteria) or Chemosynthetic (e.g., Nitrosomonas)
- Heterotrophs: Saprophytic, parasitic, symbiotic
Cyanobacteria (Blue-green algae):
- Perform oxygenic photosynthesis
- Many fix atmospheric nitrogen (e.g., Anabaena, Nostoc)
- Form blooms in polluted water
4. Kingdom Protista
- Unicellular eukaryotes — bridge between prokaryotes and multicellular eukaryotes
- Examples: Amoeba, Paramecium, Euglena, Diatoms
Sub-groups:
| Group | Features | Examples |
|---|---|---|
| Chrysophytes | Diatoms + desmids; cell wall = silica (diatomite); chief producers in oceans | Diatoms |
| Dinoflagellates | Flagellated; cause red tides (toxic blooms); bioluminescent | Gonyaulax |
| Euglenoids | No cell wall; pellicle present; photosynthetic in light, heterotrophic in dark | Euglena |
| Slime Moulds | Plasmodium stage (naked mass of protoplasm); spores dispersed by wind | Physarum |
| Protozoans | Heterotrophic; includes Amoeboid, Flagellated, Ciliated, Sporozoans | Plasmodium, Amoeba |
5. Kingdom Fungi
- Eukaryotic, heterotrophic (absorptive)
- Body = mycelium (network of hyphae)
- Cell wall = chitin
- Store food as glycogen (like animals)
- Saprophytic / parasitic / symbiotic
Classes of Fungi:
| Class | Hyphae | Spores | Sexual spores | Examples |
|---|---|---|---|---|
| Phycomycetes | Aseptate/coenocytic | Zoospores / aplanospores | Zygospores | Rhizopus, Mucor |
| Ascomycetes | Septate | Conidia | Ascospores (in asci) | Penicillium, Aspergillus, Yeast, Neurospora |
| Basidiomycetes | Septate | Absent | Basidiospores | Mushrooms, Agaricus, Ustilago, Puccinia |
| Deuteromycetes | Septate | Conidia | No sexual stage (Fungi imperfecti) | Alternaria, Colletotrichum |
Important Fungi:
- Penicillium → antibiotic Penicillin (Alexander Fleming, 1929)
- Aspergillus → aflatoxins (carcinogen)
- Yeast (Saccharomyces) → fermentation, bread making
- Neurospora → genetics research
- Puccinia → wheat rust (black rust)
- Ustilago → smut disease
6. Kingdom Plantae
- Multicellular, eukaryotic, autotrophic (photosynthesis)
- Cell wall of cellulose
- Food stored as starch
- Includes: Algae, Bryophytes, Pteridophytes, Gymnosperms, Angiosperms
| Group | Vascular tissue | Seeds | Flowers |
|---|---|---|---|
| Algae | ✗ | ✗ | ✗ |
| Bryophytes (amphibians of plant kingdom) | ✗ | ✗ | ✗ |
| Pteridophytes (first vascular plants) | ✓ | ✗ | ✗ |
| Gymnosperms | ✓ | ✓ (naked) | ✗ |
| Angiosperms | ✓ | ✓ (enclosed) | ✓ |
7. Kingdom Animalia
- Multicellular, eukaryotic
- No cell wall
- Heterotrophic — holozoic nutrition
- Food stored as glycogen
- Sexual reproduction; complex embryonic development
- Advanced neuromotor mechanisms
8. Viruses, Viroids, Prions & Lichens (Outside Five Kingdoms)
Viruses
- Acellular, non-living outside host
- Contain either DNA or RNA (never both) + protein coat (capsid)
- Obligate intracellular parasites
- Discovered by D.J. Ivanowsky (1892) — tobacco mosaic disease
- Term "virus" coined by Louis Pasteur
- W.M. Stanley crystallized tobacco mosaic virus (TMV)
- Bacteriophage = virus that infects bacteria
| Type | Disease |
|---|---|
| DNA viruses | Smallpox, herpes |
| RNA viruses | Influenza, AIDS (HIV), polio, TMV |
Viroids
- Discovered by T.O. Diener (1971)
- Smaller than viruses; RNA only, no protein coat
- Example: Potato spindle tuber disease
Prions
- Abnormal, infectious proteins — no nucleic acid
- Cause neurodegenerative diseases:
- BSE (Mad cow disease) in cattle
- CJD (Creutzfeldt-Jakob disease) in humans
Lichens
- Symbiotic association of fungi + algae/cyanobacteria
- Algae (phycobiont) = photosynthesis; Fungi (mycobiont) = water/mineral absorption
- Pollution indicators — absent in polluted areas
- Pioneer species on bare rocks
- Types: Crustose, Foliose, Fruticose
9. NEET High-Yield Points ⚡
- Whittaker (1969) → Five Kingdom Classification
- Mycoplasma = smallest living cell, no cell wall
- Diatoms = silica cell wall; chief producers in oceans; diatomite used in filtration
- Fungi cell wall = Chitin; store food as glycogen
- Euglena = has both plant and animal characters → "connecting link"
- Slime moulds → spores have cellulose wall
- Penicillin → Penicillium notatum (Alexander Fleming)
- Lichens = sensitive to SO₂ pollution
- Viroids = RNA without protein coat (T.O. Diener)
- Prions = only proteins, no nucleic acid
- Cyanobacteria fix N₂: Anabaena, Nostoc, Oscillatoria
- TMV was first crystallized virus → proved viruses are proteins
- Bacteriophage discovered by Twort and d'Hérelle
These notes cover the complete NEET syllabus for Biological Classification (Chapter 2, Class 11 Biology). Focus especially on the comparison table of five kingdoms, fungi classes, and the viruses/viroids/prions section — these yield the most MCQs in NEET.
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