Classification of Living Things

In nomenclature, naming of different organisms is done in a systematic way which is recognised in all parts of the world.

G. Simpson has defined systematics as the scientific study of types and diversity of organisms of relationships among them. It includes identification, classification and nomenclature.

Organisms are identified and classified into convenient categories based on their similarities and dissimilarities.
The process of naming the organisms is known as nomenclature.

Species → genus→ family→ order→ class→ phylum/ division→ kingdom is the hierarchy of classification.

Species is the smallest unit of taxonomical hierarchy, while kingdom is the highest unit of taxonomical hierarchy in the living world.
In the beginning, two-kingdom classification system was introduced to classify the living organisms into two basic kingdoms:

kingdom Plantae and Animalia. However, later, Whittaker introduced five-kingdom classification system to classify all the living organisms into five different kingdoms; namely, Monera, Protista, Fungi, Plantae and Animalia.

Kingdom monera consists of unicellular and prokaryotic organisms like bacteria, unicellular algae, etc.

Kingdom protista consists of unicellular and eukaryotic organisms like Amoeba, Euglena, Chlamydomonas,Paramoecium, etc.

Kingdom fungi consists of unicellular or multicellular, spore bearing organisms, which lack chlorophyll.Moulds, mushrooms, Penicillum, etc.,belong to this kingdom.

Kingdom plantae consists of multicellular and eukaryotic organisms which possess chlorophyll and hence; are autotrophic in nature.

They are further classified into thallophytes, bryophytes,pteridophytes, gymnosperms and angiosperms.

Thallophytes include organisms like spirogyra. Their body is not differentiated into roots and shoots andthey lack a vascular system.

Bryophytes include mosses and liverworts. Their body is also not well differentiated into roots and shoots. They also lack a vascular system.

Pteridophytes include Equisetum, Salvinia, etc. Their body is differentiated into roots and shoots. They possess a vascular system.

Gymnosperms include non-flowering seeded plants like pines and conifers. Their body is differentiated into stem, leaves and root system. They possess a distinct vascular system and naked seeds.

Angiosperms include flowering seeded plants like sunflowers, roses, etc. Their body is differentiated into stem, leaves and root system. They possess a distinct vascular system and their seeds are enclosed in the ovary.

Kingdom animalia also consists of multicellular and eukaryotic organisms, but they lack chlorophyll and hence; are heterotrophic in nature.

This kingdom can be broadly classified into vertebrates and invertebrates on the basis of presence or absence of a vertebral column, respectively.

Vertebrates possess distinct bony vertebral column, internal skeleton and well developed digestive system.They are classified further into five classes, Pieces, Amphibia, Reptilia, Avesand Mammalia.

Invertebrates lack a backbone or vertebral column. They can be classified as poriferans, coelenterates, platyhelminthes, nematodes, annelids, molluscs, arthropods and echinoderms.

Organisms of all the kingdoms are named scientifically as per the standard nomenclature.

The standard system of providing a name to an organism in two components, genus and species,is called binomial nomenclature. By the use of this system, an organism is known by the same name (scientific name) worldwide.

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  • Q1

    Give the common name used for angiosperms.

    Marks:1
    Answer:

    Angiosperms are also referred as the flowering plants.

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  • Q2

    Name the kingdom, in which, the eukaryotes, heterotrophs and those lacking cell wall are grouped according to five kingdom classification.

    Marks:1
    Answer:

    The eukaryotes, heterotrophs and those lacking cell wall are grouped under kingdom Animalia according to five kingdom classification.

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  • Q3

    Name the unit for biological classification?

    Marks:1
    Answer:

    Taxon (plural; taxa) is the unit of biological classification.

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  • Q4

    Name the kingdom, in which the unicellular, prokaryotes are grouped according to five kingdom classification.

    Marks:1
    Answer:

    As per five kingdom classification, the unicellular, prokaryotes are grouped under the kingdom Monera.

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  • Q5

    Name the father of taxonomy.

    Marks:1
    Answer:

    Carolus Linnaeus is the Father of Taxonomy.

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