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

What are the processes of the photochemical stage, What are the processes o...

What are the processes of the photochemical stage of the photosynthesis process? Photolysis of water, with liberation of molecular oxygen, and photophosphorylation of ADP, with

Explain the properties of good prebiotic, Explain the Properties of Good Pr...

Explain the Properties of Good Prebiotic? Thus, to summarize, we can say that a good prebiotic should have the following properties: Be active at a nutritionally feasibl

Who were james watson, Q. Who were James Watson, Maurice Wilkins and Franci...

Q. Who were James Watson, Maurice Wilkins and Francis Crick? Watson (North American), Wilkins (New Zealander) and Crick (British) were the discoverers of the molecular structur

What are the main cellular functions of potassium, What are the main cellul...

What are the main cellular functions of potassium? Besides being significant for the osmotic regulation and for the acid-base equilibrium (pH) potassium is basic for the excita

Some common air pollutants: ground level ozone, Ground level ozone: Grou...

Ground level ozone: Ground level ozone is the ozone present at the lower level of earth atmosphere. It is not emitted directly into the environment but produced by complex chemi

Experiment of a simple osmometer, A simple osmometer Remove the bottom ...

A simple osmometer Remove the bottom from a small glass bottle about 2.5 cm in diameter. Fit a one-hole stopper tightly into the bottom and put a 50 cm length of glass tubing o

Difference between tracheophytes and bryophytes, Q. What is the difference ...

Q. What is the difference between tracheophytes and bryophytes? Bryophytes are nonvascular plants (liverworts, mosses, hornworts), that is they do not have a conductive system

Tolerance range, what is the tolerance range of man and tillapia

what is the tolerance range of man and tillapia

Rehabilitation of cardiac surgical patients, REHABILITATION OF CARDIAC SURG...

REHABILITATION OF CARDIAC SURGICAL PATIENTS The goal of nursing care of cardiac surgical patient is to make the patient to come back to his normal activities. Cardiac surgica

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