Limitations of five-kingdom classification, Biology

Assignment Help:

Limitations of Five-Kingdom Classification

As already pointed out, each system of classification has its own limitations. The two-kingdom system has outlived its usefulness as it could not do justice to forms like Euglena and Volvox. The three-kingdom classification failed to accommodate properly prokaryotic forms. The limitation of the four-kingdom classification was that despite creation of kingdom Monera it failed to account for the intergradations between Protista and Animalia.

The present five kingdom system is also not the final solution to the problems of taxonomy. In this system too we have many weaknesses despite the acceptance of this system by most biologists. The exclusion of Protozoa from the animal kingdom, in this system concerns many zoologists. Protozoa share many characteristics with Metazoan animals. Most ingest their food; many have specialised organelles and advanced locomotory systems; many reproduce sexually and some flagellate protozoa are colonial with division of labour among cell types. Indeed, there is little doubt that metazoan animals evolved from one or more protozoans groups. Thus zoologists though accepting that are eukaryotic protists and not animals according to the five kingdom classification, still continue to claim Protozoa as their own. This system is also not able to show clearly the inter-relationships of various groups in all instances. Even now many phyla contain forms whose relationships are not clearly understood. among nonchordates the grouping collectively called Minor phyla has unsolved problem of phylogenetic placement. Recently, many biologists have also tried to split the kingdom Monera into two: (i) Eubacteria and (ii) Archaebacteria, leading thus to the proposal of six kingdoms.

In fact, during the past twenty years various revisions in the classification system have been discussed with the number of kingdoms ranging from 3-13. Biologists generally follow the five-kingdom-classification despite its inadequecies because it appears to be the most acceptable system today and indeed the most convenient one available.


Related Discussions:- Limitations of five-kingdom classification

Define the role of addition of acetyl groups to histones, Creb binding prot...

Creb binding protein (CBP) is a histone acetyl transferase (HAT) protein. What role does the  addition of acetyl groups to histones play during development? A. The addition of

Lipids, Lipids Lipids are oily or greasy organic compound forming about...

Lipids Lipids are oily or greasy organic compound forming about 3% of protoplasm. These are also compound of carbon hydrogen and oxygen but unlike carbohydrates. The hydrogen a

Define major arthropod classes, Q. How are the three major arthropod classe...

Q. How are the three major arthropod classes characterized according to the presence of wings? Arachnids and Crustaceans do not have wings. Most insects have wings.

Limiting factor - ecosystem, Limiting Factor - Ecosystem In all ecosys...

Limiting Factor - Ecosystem In all ecosystems one factor, usually abiotic, limits the growth of organisms and is therefore called a limiting factor. The limiting factor is one

Density - population parameters and regulation, Density - Population Parame...

Density - Population Parameters and Regulation Density is defined as number of individuals or population biomass per unit of area or volume at any given time. Biomass refers t

Photolithoautotrophs - nutritional types of microorganisms, Explain Photoli...

Explain Photolithoautotrophs - Nutritional Types of Microorganisms? These microorganisms use light as an energy source, inorganic substance as electron source and CO 2 as the

Define clinical feature and medical complication for bulimia, Define Clinic...

Define Clinical Features and Medical Complications for bulimia? Unlike, anorexia nervosa, in bulimia you will find that symptoms are more difficult to detect because patients a

Types of passive transport, Simple diffusion Only comparatively small u...

Simple diffusion Only comparatively small uncharged or hydrophobic molecules (H2O, O2, and CO2, other gases, urea and ethanol)   cross   the lipid   bilayer   through simple

What is the climax stage of an ecological succession, What is the climax st...

What is the climax stage of an ecological succession? The climax stage is the stage of the ecological succession in which the community of an ecosystem becomes stable and does

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd