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

Determine the case when starches treated with heat, Determine the case when...

Determine the case when starches treated with heat In the case of starches treated with heat in presence of acid or alkali, the alteration is a minor fragmentation; similarly,

Types of neurons, TYPE S OF NEURONS - The neurons are classified on th...

TYPE S OF NEURONS - The neurons are classified on the basis of their structure and function. (A) On the basis of the structure, the neurons are of four types.

What is neuron cell body, Q. What is an example of a situation in which the...

Q. What is an example of a situation in which the neuron cell body is located in a part of the body and its axonal terminal portion is in another distant part of the body? Why does

Origin and evolution of metazoa, Origin and Evolution of Metazoa Most ...

Origin and Evolution of Metazoa Most of the early metazoans were soft bodied and so their fossils are rare. The extremely fragmented fossil record does not shed any specific l

What are the main water properties, What are the main water properties that...

What are the main water properties that make water special for life? The water properties that make water biologically significant are molecular polarity, thermal stability (el

What is enhancers , While  various  positive  control  components  li...

While  various  positive  control  components  lie  close  to the  gene  they  regulate additional can be situated long distances away (sometimes 10-50 kb) either upstream or downs

State the versions of binocular movements, State the Versions of Binocular ...

State the Versions of Binocular movements Versions are movements of both eyes in the same direction. a) Dextroversions: Movements of both eyes to'the right side. b) Levov

How do antibodies work to neutralize antigens, Q. How do antibodies work to...

Q. How do antibodies work to neutralize antigens? The immunoglobulins or antibodies act to facilitate the destruction of antigens: they attract phagocytic leukocytes, they dire

What is absorption, What is absorption?   Absorption involves  the  tr...

What is absorption?   Absorption involves  the  transfer of materials  through  the mucosa of the  alimentary tract  into blood and lymph vessels.

Examine the benefits and risks bird flu, Examine the benefits and risks bir...

Examine the benefits and risks bird flu research poses to society. Indicate if you believe there are more benefits or more risks associated with this research, and give a rationale

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