Key Notes:

Definition of Classification:

• Classification is the process of grouping organisms based on similarities and differences to study and understand them systematically.

Need for Classification:

• Simplifies the study of the immense diversity of life.
• Helps identify and group organisms.
• Understands evolutionary relationships.

Basis of Classification:

• Cell Structure: Whether the organism is unicellular (single-celled) or multicellular (many-celled).
• Mode of Nutrition: Autotrophic (self-feeding, e.g., plants) or heterotrophic (dependent on others, e.g., animals).
• Body Organization: Levels of complexity from simple (e.g., sponges) to complex (e.g., mammals).
• Reproduction: Asexual or sexual methods of reproduction.
• Evolutionary Relationships: Organisms are classified based on their evolutionary history and ancestry.

Levels of Classification (Hierarchy):

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Five Kingdom System of Classification:

• Proposed by R.H. Whittaker in 1969.
• The five kingdoms are:
  • Monera: Prokaryotic organisms like bacteria.
  • Protista: Unicellular eukaryotes.
  • Fungi: Non-green, spore-producing organisms.
  • Plantae: Autotrophic, multicellular plants.
  • Animalia: Heterotrophic, multicellular animals.

Importance of Scientific Names:

• Universal recognition of organisms.
• Avoids confusion caused by local or common names.

Binomial Nomenclature:

• Introduced by Carolus Linnaeus.
• Each organism is given a two-part name: Genus and Species (e.g., Homo sapiens).

Characteristics for Classification:

• Type of cell (prokaryotic/eukaryotic).
• Body structure and organization.
• Reproductive strategy and life cycle.
• Habitat and ecological role.

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