Science: Classification of Living Organisms: The Five Kingdom of Life (For CBSE, ICSE, IAS, NET, NRA 2022)

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The Five Kingdom of Life

In 1982, Margulius and Schwartz revised the five-kingdom classification. It includes one prokaryote and four eukaryote kingdoms- the Protoctista, the Fungi, the Plantae and the Animalia. This Scheme is widely accepted.

Kingdom Monera (Prokaryote) It is divided in to Archaebacteria (Archae) and Eubacteria (Bacteria) . Out of the two Archae is more ancient.

Archaebacteria

Most of them are autotrophs and only a few photosynthesize. They derive their energy for metabolic activities, from the oxidation of chemical energy sources like reduced gases – Ammonia, methane or hydrogen Sulphide. In the presence of these chemicals it can manufacture their own amino acids acid proteins.

They are further divided in to three groups:

  • Methanogens (manufacture methane) ,
  • Thermoacidophiles (Favour extremely hot and acidic environments) , and
  • Halophiles (grow in very salty environment) .

Eubacteria

They generally lack membrane-enclosed organelles like nucleus etc. Nucleoid serves as a single chromosome. Electron transport and photosynthesis takes place on plasma membrane, which sometimes folds inwards into the cell՚s interior.

Kingdom Protista (Protoctista)

This group includes many kinds of unicellular eukaryotic organisms such as unicellular algae, protozoans and unicellular fungi. Some of these organisms use appendages i.e.. hair like structure cilia like in paramecium or whip-like flagellum e. g. euglena. Their mode of nutrition can be autotrophic (Unicellular algae, diatoms) or heterotrophic (protozoans) . Examples: Unicellular algae, chlorella, Euglena, Trypanosoma (causes sleeping sickness) , Amoeba, Plasmodium, Paramecium, Chlamydomonas etc.

Kingdom Fungi

  • Non-green plants which are not photosynthetic. They are heterotrophic and eukaryotic organisms. Some fungi are parasites can draw nutrients from living cells of their host- plants like Puccinia, Ustilago etc. Some are decomposers like Penicillium etc. and saprophytes derive their nourishment from dead remains of plants and animals.
  • Fungus may be unicellular or filamentous. The body of multicellular and filamentous is called mycelium and composed of several thread-like structures called hyphae.
  • The reserve food is glycogen in them.

Examples: Bread mold, Yeast, sponge, mushroom, rust, smut etc.

Kingdom Plantae

  • Includes multicellular organisms except relatives of algae.
  • They are eukaryotes.
  • Cell wall is present.
  • Possesses a single large central vacuole bounded by tonoplast (membrane) .
  • Reserve food for plants in the form of starch and lipids.
  • Plastids are present also some have photosynthetic pigments called chloroplasts.
  • Autotrophic nutrition.
  • Growth of plants is indefinite.
  • Irregular body due to presence of branches.

Kingdom Animalia

  • Animals have wall less eukaryotic cells.
  • Heterotrophic nutrition.
  • Growth of animals is limited.
  • Animals generally possess a definite shape, size and symmetry.
  • Most animals are mobile.
  • Animals have organisation of cellular, tissue, organs and organ system level.

Classification of Plants

Classification of Plants

Non-Vascular Plants

  • The first classification of plants is the non-vascular plants.
  • As their name implies, nonvascular plants lack vascular tissues that can help them transport water and nutrients.
  • Nonvascular plants are considered to be the earliest living plants in the planet. However, fossils have not been found because these types of plants fossilized poorly.
  • The most common non-vascular plants include the members of the Phylum.

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