Biological Classification Notes: Class 11 Biology Chapter 2
Class 11 Biology Chapter 2 Biological Classification covers the Five Kingdom Classification system proposed by R.H. Whittaker, and the characteristics of Monera, Protista, Fungi, Plantae, and Animalia, along with viruses, viroids, and lichens.
Overview of Topics & Subtopics (Click to Jump)
1. Five Kingdom Classification (Whittaker)
Short Note:
• R.H. Whittaker (1969) proposed five kingdoms based on cell structure, mode of nutrition, body organisation, and phylogenetic relationships: Monera, Protista, Fungi, Plantae, and Animalia.
2. Kingdom Monera and Kingdom Protista
Short Note:
• Monera includes all prokaryotes (bacteria), which lack a true nucleus and membrane-bound organelles; further classified based on cell wall, motility, and nutrition (archaebacteria, eubacteria).
• Protista includes unicellular eukaryotic organisms, such as chrysophytes, dinoflagellates, euglenoids, slime moulds, and protozoans.
3. Kingdom Fungi
Short Note:
• Fungi are eukaryotic, heterotrophic (saprophytic) organisms with a cell wall made of chitin; body is generally made of thread-like structures called hyphae, collectively forming a mycelium.
• Classified into Phycomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes based on the mode of spore formation.
4. Viruses, Viroids and Lichens
Short Note:
• Viruses are non-cellular, obligate intracellular parasites, composed of genetic material (DNA or RNA) surrounded by a protein coat (capsid); they are inert outside a living host.
• Viroids (discovered by T.O. Diener) are smaller than viruses and consist only of free RNA, without a protein coat.
• Lichens are a symbiotic association between algae (phycobiont, provides food) and fungi (mycobiont, provides shelter and absorption).