Subjects /Biology / Classification of Livings

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INTRODUCTION
06 Apr 2021

The scientific practice of identifying, naming and grouping of the living organisms is called classification. Therefore, it is nothing but categorisation of organisms in different groups.

Taxonomy is the branch of biology which deals with the classification of living organisms. Under this branch, organisms are named and described as well.

Systematics is the branch of biology which deals with grouping and arranging various organisms in hierarchical classification.

Advantages of Classification

  • It helps to identify different organisms and place them under particular groups.
  • It provides pattern and helps in systematic study of organisms.
  • It shows relationship between different organisms.
  • It helps to understand the process of evolution from the simple to complex organisms.
Read further for all the five kingdom classification and its notes.

Macro and Micro Classification

Macro Classification

  • Carolus Linnaeus in 1758 divided all organisms into two kingdoms in his book Systema Nature as:
    • Plantae – The Kingdom of Plants
    • Animalia – The Kingdom of Animals
  • Since, organisms like bacteria, virus and fungi were left out of this classification, therefore, new classification was considered.

Five Kingdom Classification

  • Five kingdom classification was proposed by R. H. Whittaker in 1969 based on three criteria:
    • Cell structure of the organism
    • Body Structure of the organism
    • Mode of nutrition of the organism
  • It is also called the Micro classification or Modern classification of the organisms.

The five kingdom classification chart is shown below:

Five kingdom classification chart

Monera

  • It includes all unicellular prokaryotic organisms like bacteria and cynobacteria.
  • These organisms are microscopic i.e. cannot be seen with naked eyes.
  • The cell does not have well defined nucleus. The DNA is present in the cell without being enclosed by nuclear membrane.
  • They do not have cell organelles. The cell has rigid cell wall.
  • For example:
    • Blue green algae
    • bacteria

Protista

  • It includes unicellular plants and animals.
  • They are eukaryotic i.e. they have a well – defined nucleus with a nuclear membrane.
  • The cell has cell organelles.
  • These organisms are usually found in aquatic habitat.
  • Some examples include:
    • Euglena
    • Amoeba
    • Paramecium

Fungi

  • It includes non-green plants.
  • They are multicellular and eukaryotic organisms.
  • These are heterotrophs i.e. they cannot make their own food.
  • It has saprophytic mode of nutrition i.e. they get their food from dead and decaying matter.
  • They are made of thread-like hyphae structure.
  • The green or black substance found on rotten bread is fungi only.
  • For example:
    • Mushroom
    • Mucor
    • Albugo
    • Moulds

Plantae

  • It includes all the green plants except algae and organisms already belonging to Monera or Protista.
  • These are multicellular and eukaryotic plants.
  • They have Chlorophyll that makes the process of photosynthesis possible.
  • These are autotrophs i.e. they make their own food.
  • For example:
    • Bryophytes
    • Petridophytes
    • Gymnosperms
    • Angiosperms

Animalia

  • All animals except Protozoa comes under this group.
  • These are multicellular animals.
  • The cell structure is well developed. The DNA and RNA is present in the nucleus.
  • The chlorophyll and cell wall are absent.
  • These are heterotrophs i.e. the cell cannot make food on its own.
  • For example:
    • Human
    • Lion
    • Whale

Bionomial Nomenclature

  • The naming of an organism is called Nomenclature.
  • Carolus Linnaeus  is the father of taxonomy.
  • A proper system to name the organisms was needed so that by the name could reflect the group it belongs to.
  • Every organism is represented by a proper name.
  • In binomial nomenclature, the name of an organism is composed of two words in Latin language.
  • The first word is Genus and is called the Generic name. It always starts with capital letter.
  • The second word refers to the name of the species and is called the Specific name. The first letter is written with small alphabet.

Scientific names of some organisms are:

S.No

Organism/Plant

Scientific Name

1.

Wheat

Triticum aestivum

2.

Man

Homo sapiens

3.

Rice

Oryza sativa

4.

Cat

Felis domestica

5.

Frog

Rana tigrine

6.

Mango

Magnifera indica

7.

Pea

Pisum sativum

8.

Tiger

Panthera Tigris

9.

Dog

Canis familiaris

10.

Banana

Musa Paradisiaca

11.

Cow

Bos indicus

 

Did You Know

  • Linnaeus is called the Father of Taxonomy.
  • Genera Plantarium book was written by Benthem and Hooker.