Golden Key Points -Chapter2-Biological Classification

Golden Key Points

Classification of Living Organisms:
- Aristotle initiated classification based on morphological characters.
- Linnaeus developed a two-kingdom system: Plantae and Animalia.
- Whittaker proposed a Five Kingdom Classification: Monera, Protista, Fungi, Plantae, and Animalia.
- Later, the Three-Domain System was proposed, adding Archaea and Bacteria as separate domains.
Kingdom Monera:
- Includes bacteria, abundant microorganisms found in various habitats.
- Classified based on shape: cocci (spherical), bacilli (rod-shaped), vibrio (comma-shaped), spirilla (spiral).
- Show extensive metabolic diversity, including autotrophic and heterotrophic modes of nutrition.
- Some bacteria live in extreme habitats like hot springs, deserts, and deep oceans.
- Archaebacteria have unique cell wall structures and survive in extreme conditions.
Kingdom Protista:
- Includes single-celled eukaryotes with diverse characteristics.
- Boundaries of this kingdom are not well defined.
- Examples include chrysophytes, dinoflagellates, euglenoids, slime molds, and protozoans.
- Protists primarily aquatic and exhibit a wide range of reproductive strategies.
Kingdom Fungi:
- Unique kingdom of heterotrophic organisms with diverse morphology and habitat.
- Consists of filamentous structures called hyphae, forming a mycelium.
- Reproduction occurs through vegetative means (fragmentation, fission, budding) and spore formation (asexual and sexual).
- Includes various classes like Phycomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes.
Viruses, Viroids, Prions, and Lichens:
- Viruses are acellular organisms with inert crystalline structures, obligate parasites causing diseases in plants and animals.
- Viroids are smaller infectious agents consisting of free RNA, causing diseases like potato spindle tuber disease.
- Prions are infectious agents consisting of abnormally folded proteins, associated with neurological diseases in animals and humans.
- Lichens are symbiotic associations between algae and fungi, serving as pollution indicators and mutually beneficial partnerships.