Diversity in the Living World

Diversity in the Living World

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Characteristics of Living Organism

  • Living organisms has the ability to grow. Increase in mass and increase in number of individuals are essential criterion for the growth of the living organism. Growth of multicellular organisms occurs due to cell division.
  • Reproduction is another characteristic of living organisms.
  • Metabolism is another characteristic of living organisms. There are various catabolic and anabolic reactions occurs in an organism throughout their life.
  • Cellular organization is the defining feature of all characteristics organisms
  • Living organisms are able to respond to the external stimuli.

Diversity in the Living World

The process of naming of an organism is known as nomenclature. A principles and criterion was given for naming the organisms, by scientist known as International Code for Botanical nomenclature (ICBN). For animals, International Code of Zoological Nomenclature. This helps the scientist from all over the world to interact with each other using the same name.

Each name consists of two parts-the first part is the generic name and the second part is the name of the species. This is known as Binomial Nomenclature. This was given by a scientist known as Carolus Linnaeus. Rules for nomenclature-

  • Biological names are in Latin and written in italics.
  • The first word represents the Genus and the second represents the species.
  • Both the words, that is, genus and species name should be underlined.
  • The first word genus starts with a capital letter and second word species starts with a small letter. For example, mango is written as Mangifera indica
  • Name of the author comes after species name.

Classification is the process of grouping the organisms based on some observable characteristics.

Organisms are also classified based on the taxa. This type of classification is known as taxonomy. Taxa is defined as the group of organisms or population presented as same unit based on some characteristics.

The study of different kind of organisms and their relationships is known as systematics. Systematics include classification, nomenclature, and identification.

Taxonomic Categories


Group of individuals which are capable to interbreeding is known as species.


It represents a group of related species which share one or more characteristics in common.


It includes group of related genera but with less similarities with genus and species. In case of plants, family contains both vegetative and reproductive features. For example, Datura, Solanum, and Petunia are placed in a family known as Solanaceae.


It is the assemblage of families with only few similarities.


Related orders are included in class. For example, class Mammalia includes order Primata along with order Carnivora.


Different classes combine to form phylum. Fishes, amphibian, reptiles, birds, and mammals are placed in the phylum Chordata.


Different phylum forms the kingdom. Animals are placed in animal kingdom whereas plants are placed in plant kingdom.


It is placed on the highest position. Kingdom forms a domain.

Linnaean Hierarchy

Fig.1. Linnaean Hierarchy


It is a collection of preserved plant material along with the scientific data associated with it.

Uses of Herbarium

  • Studying plant taxonomy.
  • To identify the flora of the area.
  • It stores the historic record of vegetation with time.
  • Source of plant DNA is used in plant taxonomy
  • Study of molecular taxonomy.
  • Repository for viable seeds of rare species

Botanical Gardens

  • Collection of living plants for reference.
  • They also contain special collections such as alpine plants, exotic plants, tropical plants etc.


  • They are meant for educational purpose mainly. For example, they are usually set up in colleges, schools etc.

Zoological Parks

  • These are parks in which animals are kept in enclosure and displaced to common public. They are meant for recreation purposes


It is a taxonomic aid for identification of plants and animals based on certain similarities and dissimilarities

Define Biological Classification

The process of grouping the organisms based on certain similarities such as physical characteristics is known as biological classification.

Linnaeus proposed the two kingdoms of classification. He classified organism into plant kingdom as Plantae and animal kingdom as Animalia.

Five Kingdom Classification

Then came the R.H. Whittaker whose proposed five kingdoms of classification. The five kingdoms classification is as follows-  Monera, Protista, Fungi, Plantae, and Animalia.



nucleus is not bound by a nuclear membrane

cell wall is present


movement is through flagella,


via diffusion.

They are divided into Archaebacteria and Eubacteria

Nostoc, Anaebena


Fig. 2. Anabaena


Single celled eukaryotes, eukaryotic organisms, move by cilia and flagella,

they form cyst.

It is divided into Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans.



Gonyaulax catenella, Noctiluca scintillans, Euglena, Plasmodium, Amoeba, Trypanosoma



Fig. 3. Amoeba












Heterotrophic organisms,

reproduction in fungi occurs by- budding, fragmentation, and fission, asexual reproduction occurs by means of spores known as conidia, zoospores or sporangiospores,

sexual reproduction occurs by oospores, ascospores and basidiospores

the vegetative part of the fungus is known as mycelium.

Fungi is divided into -Phycomycetes









pigment present is chlorophyll,

cell wall is made up of cellulose,

exhibit the phenomenon of alternation of generation.

Penicillium, Aspergillus













Marsilea, Azolla, Adiantum


Fig. 4.  Penicillium


Fig. 5.  Marsilea


Multicellular organisms,

bilaterally symmetrical,

well-developed organ system,

well-developed locomotory organs,

respiration occurs by gills, book lungs, book gills, skin, lungs,

kidneys are the main respiratory organs

Rattus (Rat), Canis (Dog), Felis (Cat), Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Oviparous-Ornithorhynchus (Platypus)


Fig. 6. Macropus

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