Question

Discuss how classification systems have undergone several changes over a period of time?

Answer 1

Hint: The classification of organisms had a very vast history, many researches and classification systems were introduced to classify the organisms, after all the failures finally the five kingdom classification was introduced that includes all the organisms.

Complete Answer:
- So, the very first attempt of classification is carried out by Aristotle. He has classified the plants as shrubs, herbs, and trees and for animals he had classified on the basis of presence and absence of red blood cells but these criteria of classification have failed to classify all the organisms.
- After the failure of Aristotle classification of organisms, Linnaeus gave the two kingdom classification system, according to his classification all the organisms were divided in plant and animal kingdoms. But this system of classification also failed to differentiate between unicellular and multicellular organisms and between prokaryotes and eukaryotes; hence, there were many such organisms which could not be classified under this two kingdom classification system.
- So, Ernest Haeckel studied about the unicellular eukaryotic organisms and classified them as a separate kingdom and named it Protista, and then the classification was made based on three kingdom classification. But still it did not get successful as these kingdoms failed to classify prokaryotic organisms.
- Then Copeland separated all the prokaryotic organisms into a kingdom and named it Monera and the four kingdom classification came into existence.
- And finally, R.H.Whittaker gives the five kingdom classification where all the organisms are classified based on their physiological structure, habitat, and anatomical structure etc. which we are studying today. His study includes the fifth kingdom that is fungi that includes the achlorophyllous and decomposers.
- Therefore, the five kingdom classification are; Monera, Protista, Fungi, Plantae, and Animalia.

Note: The Monera includes all the unicellular and prokaryotic organisms, the Protista includes all the unicellular eukaryotic organisms, the fungi includes the multicellular prokaryotes, the kingdom plantae includes all the plant that exist, and the kingdom animalia includes all the multicellular animals.