# Biological Classification Notes, Class 11 Biology | SwaVid Biological Classification, NCERT Class 11 Biology: notes with key ideas, key terms, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-11/biology/chapter/biological-classification Source: https://www.swavid.com/cbse/class-11/biology/chapter/biological-classification # Biological Classification ## Key terms ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 11 Biology on SwaVid ### Systems of classification ### Kingdom Monera ### Kingdom Protista ### Kingdom Fungi ### Four classes of fungi ### Plantae and Animalia ### Viruses, viroids, prions, and lichens ### Next chapter ### Related chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 11 › Biology › Biological Classification Notes written by SwaVid from the NCERT textbook. Class 11 Biology, Chapter 2. Key ideas, formulas and common mistakes. CBSE prints 15 marks for Unit I, not for this chapter alone. Short answer. This chapter explains the systematic classification of living organisms into kingdoms based on cell structure, body organisation, and mode of nutrition. Students learn the distinguishing features of Monera, Protista, Fungi, Plantae, and Animalia, along with acellular entities like viruses, viroids, and prions. Source: NCERT Biology (Reprint 2026-27) , Chapter 2, Biological Classification Aristotle used simple morphological characters to classify plants and animals, while Linnaeus gave the two-kingdom system. R.H. Whittaker proposed the five-kingdom system in 1969 based on cell structure, body organisation, mode of nutrition, reproduction, and phylogenetic relationships. Bacteria are the sole members of Monera and live in diverse habitats. Archaebacteria survive extreme conditions due to a unique cell wall structure, while Eubacteria include photosynthetic cyanobacteria, chemosynthetic autotrophs, heterotrophic bacteria, and wall-less mycoplasma. Protists are single-celled eukaryotes primarily found in aquatic environments. This kingdom includes photosynthetic chrysophytes and dinoflagellates, mixotrophic euglenoids, saprophytic slime moulds, and predatory or parasitic protozoans. Fungi are heterotrophic, mostly multicellular eukaryotic organisms with cell walls made of chitin and polysaccharides. They reproduce vegetatively, asexually through spores like conidia or sporangiospores, and sexually via plasmogamy, karyogamy, and meiosis. Fungi are grouped into Phycomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes based on mycelium morphology, spore formation, and fruiting bodies. Deuteromycetes lack sexual stages and are known as imperfect fungi. Kingdom Plantae contains eukaryotic autotrophs with cellulosic walls that show alternation of generations. Kingdom Animalia contains heterotrophic, multicellular eukaryotes lacking cell walls that ingest food and store glycogen or fat. Acellular entities like viruses consist of nucleic acid within a protein capsid and are obligate intracellular parasites. Viroids are free infectious RNA molecules without a protein coat, prions are abnormally folded infectious proteins, and lichens are symbiotic associations of algae and fungi. Try each question first. Then tap it to see the answer. Identify the presence of a flexible protein layer called a pellicle instead of a cell wall. Recall that mixotrophic nutrition with two unequal flagella is characteristic of euglenoids. Place euglenoids in Kingdom Protista because they are unicellular eukaryotes. Euglenoids, Kingdom Protista Identify the group commonly known as fungi imperfecti. Recall that only vegetative or asexual phases are known in these fungi. Name the class containing Alternaria, Colletotrichum, and Trichoderma. Deuteromycetes First step is the fusion of protoplasms between two motile or non-motile gametes (plasmogamy). Second step is the fusion of the two haploid nuclei (karyogamy). Third step is meiosis in the zygote resulting in haploid spores. Plasmogamy, karyogamy, and meiosis Plant Kingdom . The Living World . Animal Kingdom . The 19 chapters of Class 11 Biology . CBSE does not give marks to one chapter. It prints 15 marks for Unit I, Diversity of Living Organisms, which includes Biological Classification. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Plant Kingdom. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Ch 2 NCERT book - 15 marks, Unit I - 3 quick checks - Classifying blue-green algae under Kingdom Plantae because they are photosynthetic . Place blue-green algae (cyanobacteria) in Kingdom Monera because they have a prokaryotic cellular structure. - Confusing viroids with viruses by assuming viroids also have a protein capsid . Remember that viroids are composed only of naked, free RNA of low molecular weight and lack any protein coat. - Assuming that all fungi possess septate hyphae . Note that Phycomycetes have coenocytic, aseptate mycelium, unlike Ascomycetes and Basidiomycetes which are septate. - Writing that viruses contain both RNA and DNA . Remember that no virus contains both DNA and RNA; it contains either DNA or RNA as its genetic material. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 11](https://www.swavid.com/cbse/class-11) - [Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup) - [All 19 chapters](https://www.swavid.com/cbse/class-11/biology/chapters) - [NCERT Biology (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/plant-kingdom) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/the-living-world) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/animal-kingdom) - [Class 11 Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup)