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

Genotype for each individual, The allele that causes albinism (p) is recess...

The allele that causes albinism (p) is recessive to the allele for normal pigmentation (P). A normal woman whose father is an albino marries an albino man whose parents are both no

Digestive system, Digestive system is one of eleven major body organ syste...

Digestive system is one of eleven major body organ systems in animals; it converts food from the external environment into the nutrient molecules which can be used and stored by t

Respiration, how do respiration take place in animal????

how do respiration take place in animal????

Define precaution-estimation of nitrogen and protein content, Define Precau...

Define Precautions - Estimation of Nitrogen and Protein Content? 1. The apparatus should be airtight to prevent leakage of NH 3 . 2. The tip of the delivery tube should be i

Explain the metabolic aberrations of underweight, Explain the Metabolic Abe...

Explain the Metabolic Aberrations of Underweight? When energy intake falls below the minimal requirements, the body responds with an orderly physiologic adaptation involving th

Conjugated proteins, CONJUG A TE D PROTEINS Besides being made of po...

CONJUG A TE D PROTEINS Besides being made of polypeptides, the conjugated proteins posses additional groups, metals or ions. Consists of protein and non-protein parts.

Explain the recombinantion of dna, Explain the Recombinantion of DNA ? ...

Explain the Recombinantion of DNA ? Recombinant DNA is made by combining DNA from more than one source - often from very different species. The technique is now the basis fo

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