Biological Classification Class 11 Notes Biology Chapter 2 - CBSE

Chapter : 2

Biological Classification

Scientific procedure of arranging organisms into a hierarchical series of groups and sub-groups on the basis of their similarities and dissimilarities.



  • Trees
  • Shrubs
  • Herbs


  • With RBC
  • Without RBC

Linnaeus: 2 Kingdom Classifications

  • Plantae
  • Animalia

Whittaker 5 Kingdom Classifications

  • Animals
  • Plants
  • Fungi
  • Bacteria
  • Protists


It is defined as the organism of particular kind whose members can interbreed among themselves to produce fertile young ones.

Grouping In A Sequence

  • Genus: Similar species constitute next higher category.
  • Family: A group of genera with certain common characteristics.
  • Order: A group of related families.
  • Class: Related orders make class.
  • Phylum: Largest division in classification.
  • Kingdom: Largest division of living being.

Five Kingdom Classification


  • Prokaryotic type
  • Some have cells walls.
  • Either autotrophic or heterotrophic
  • E.g. Blue green algae, mycoplasma etc.


  • Unicellular, eukaryotic organisms
  • Some bear cilia or flagella
  • Either autotrophic or heterotrophic
  • E.g. Protozoans, diatoms etc.


  • Made up of hyphae
  • Cell wall contains chitin
  • Heterotrophic
  • E.g. Yeast, mushrooms etc.


  • Multicellular
  • Photosynthetic
  • Autotrophic
  • Different plantae are: Thallophyta, Bryophyta, Petridophytes, Gymnosperms, Angiosperms, Monocots, Dicots.


  • Multicellular
  • No cell wall
  • Usually mobile
  • Heterotyphic
  • Different animalia are: Porifera, Cnidaria, Platihelminthes, Nematoda, Annelida, Arthropoda, molluscua, Echinodermata, Chordata.


Symbiotic association of algae and fungi.


Infectious acellular chemical having either DNA or RNA as genetic material covered by protein coat called capsid.


Naked DNA or RNA without protein coat, smaller than virus.