Three and four kingdom classification, Biology

Assignment Help:

Three and Four Kingdom Classification

The two-kingdom classification, while solving many of the problems of classification, failed to establish clear-cut distinction between plants and animals. It also could not indicate correct relationships among organisms. Difficulty was particularly felt at the unicellular level. There are forms like Euglena and Volvox which possess both plant and animal like characters. On the one had like plants they contain chlorophyll and manufacture their food by photosynthesis.

On the other Kind the" actively swim like animals. Due to this reason zoologists classified them with animals under phylum protozoa while botanists included them as plants under Thallophyta. In addition to this, there are some other organisms like Peranema which closely resemble Euglena in structure but lack chlorophyll. These are not included among plants but were always classified under Protozoa. In order to overcome such difficulties, Haeckel (1866) proposed setting up of a third kingdom under the name Protista (meaning the very first) to include all thallophytes and protozoans. This kingdom also included bacteria and blue-green algae. According to this system the old kingdom Plantae included only the members of Embryophyta while Animalia was left only with Parazoa and Metazoa. However, many forms such as blue-green algae and bacteria of Protista lack membrane- bound nuclei. So, a fourth kingdom, Monera, was later established by Whittaker in order to accommodate these forms. From the evolutionary point of view the kingdom Monera is regarded as the most primitive.


Related Discussions:- Three and four kingdom classification

Define the bioavailability of cyanocobalamin, Define the Bioavailability of...

Define the Bioavailability of cyanocobalamin? Vitamin B 12 is widely available. Availability is more from non-vegetarian foods as described earlier under the food sources sec

Kuch, how vagina is inserted in cock

how vagina is inserted in cock

Descent of the testis, Descent of the Testis The testis develops on ...

Descent of the Testis The testis develops on the posterior abdominal wall at the mesonephric ridge. To reach the adult position in the scrotum, it must decent. A fibrous cor

What is polygenic inheritance?, What is polygenic inheritance? How does it ...

What is polygenic inheritance? How does it work?  The Polygenic inheritance, also called as quantitative inheritance, is the gene interaction in which a given trait is conditio

Explain six different genotypes, ABO blood groups in humans are controlled ...

ABO blood groups in humans are controlled by the gene I. It has three alleles - IA, IB and i. As there are three dissimilar alleles, six different genotypes are possible. How many

Coronary arteries, Coronary Arteries The right coronary artery origina...

Coronary Arteries The right coronary artery originates form the right aortic valvular cusp, its, SA nodal branch supplies the SA node and AV nodal branch supply the AV nod

Tasks of orientation phase - phases of nurse, Tasks of  Orientation Phase: ...

Tasks of  Orientation Phase: Establishing contact with the patient  Developing  the pactlcontract  Talking to the patient  Establishing Contact with the Patient

Human evolution, In the last unit we traced the human evolutionary history ...

In the last unit we traced the human evolutionary history mostly from a palaeontological viewpoint. Although still fragmentary, the available fossil evidence makes it possible to c

Phylum Protozoa, Make a detailed study on Phylum Protozoa taking an example...

Make a detailed study on Phylum Protozoa taking an example with clear labeled diagrams.

Explain the primary stain - ziehl-neelsen method, Explain the Primary Stain...

Explain the Primary Stain - Ziehl-Neelsen Method? Ordinary aqueous stains like methylene blue, crystal violet, etc. are not able to stain most of the species of Mycobacteria. C

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