Biology - Classification of Organisms
The technique of classifying organisms is known as Taxonomy.
Taxonomy is made up of two words i.e. ‘Taxis,’ which means ‘arrangement’ and ‘Nomos,’ which means ‘method.’
The Swedish botanist Carolus (Carl) Linneaeus has developed the modern taxonomic system.
Linneaeus has developed the following hierarchy of groups to explain the taxonomy −
In this hierarchy, Domain is the highest order and the broadest category and Species is the lowest order category.
Further based on the difference between eukaryotes and prokaryotes (cells) ‘Domains’ classified into three broad categories namely −
Archea(Archeabacteria) − It comprises the bacteria that live in extreme environments.
Eubacteria − It comprises the bacteria that found in everyday life.
Eukaryote − It comprises almost all the world's visible living things.
The above given three domains are further categorized into Five following Kingdoms −
Let’s discuss each kingdom in brief −
Monera − It comprises the unicellular organisms, e.g. bacteria.
Protista − Similar to monera (unicellular), but more developed and complex. It contains nucleus.
Plantae − All plants from smallest (such as algae) to the largest (such as Pine, Eucalyptus trees, etc.) are studied under this kingdom.
Fungi − It is a group of eukaryotic organisms that comprises microorganisms such as yeasts, molds, and mushrooms. The organisms of this kingdom do not make their food, they are basically parasites.
Animalia − It includes all the multicellular and eukaryotic organisms (of animal group). It is also known as Metazoa.
The naming culture (of different organisms) practiced uniformly across the world is known as binomial nomenclature.
Binomial Nomenclature largely consists of two words – the first word beginning with a capital letter and known as genus (of the organism) and the second word begins with lower case letter and defines the species of the organism.
Binomial Nomenclature must be written in italic and also known as scientific name.
For example, the binomial nomenclature of human is - Homo sapiens; tiger - Panthera tigris, etc.
Eukaryotes and Prokaryotes
Cells are fundamentally categorized by prokaryotes and eukaryotes.
Prokaryotes are the smallest and simplest type of cells.
Prokaryotes have no true nucleus and no membrane-bound organelles. E.g. Bacteria.
Prokaryotes’ Genome consists of single chromosome.
Reproduction is asexual; basically mitosis type.
Eukaryotes are complex in structure.
Eukaryotes have nuclei and membrane-bound organelles.
Eukaryotes’ Genome consists of numerous chromosomes.
Reproduction is sexual; by mitosis and meiosis.