ll BIOLOGICAL_CLASSIFICATION(with notes)_CH_2_NEET/BOARD ll

ll BIOLOGICAL_CLASSIFICATION_CH_2_NEET/BOARD ll
### Biological Classification Notes

**1. Definition:**
Biological classification, or taxonomy, is the systematic categorization of living organisms based on shared characteristics and evolutionary relationships.

**2. Hierarchical Levels:**
The classification system is organized into several hierarchical levels:

- **Domain:** The highest rank (e.g., Archaea, Bacteria, Eukarya).
- **Kingdom:** Groups within domains (e.g., Animalia, Plantae, Fungi).
- **Phylum:** Further divides kingdoms (e.g., Chordata for animals with a backbone).
- **Class:** Subdivision of phyla (e.g., Mammalia for mammals).
- **Order:** Groups of related families (e.g., Carnivora for carnivorous mammals).
-Family:Groups of related genera (e.g., Felidae for cats).
Genus: A group of closely related species (e.g.Panthera for big cats).
Species: The most specific level, representing individual organisms capable of interbreeding (e.g. Panthera leo for lions).

3. Binomial Nomenclature:
- Developed by Carl Linnaeus, this system assigns each species a two-part name: the genus name (capitalized) and the species identifier (lowercase), both italicized (e.g. Homo sapiens).

4. Taxonomic Hierarchy Example:
For the domestic cat:
- Domain: Eukarya
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Carnivora
- Family: Felidae
- Genus: Felis
- Species: Felis catus

5. Classification Criteria:
Organisms are classified based on various criteria:
Morphological: Physical traits and structures.
Genetic: DNA sequences and genetic similarities.
Ecological: Roles in the ecosystem and interactions.
Behavioral:Patterns of behavior and adaptation.

6. Importance of Classification:
- Helps in identifying and studying biodiversity.
- Facilitates communication and information sharing in biology.
- Aids in conservation efforts and understanding evolutionary relationships.

7. Modern Classification:
- Incorporates phylogenetics, which uses genetic data to determine evolutionary relationships.
- Recognizes the importance of evolutionary history (cladistics).
Key Terms:
Phylogeny:The evolutionary history of an organism.
Cladistics:A method of classification based on common ancestry.
Synapomorphy:A shared derived trait used to infer relationships.