What is five kingdom system of classification? In order to recommend a superior method of classification of living organisms, R.H. Whittaker (1969) an American Taxonomist separated all the organisms into Five kingdoms based on their phylogenetic relationships. The five kingdom system of classification takes into account the following important criteria.
- Complexity of Cell structure – prokaryote to Eukaryote
- Mode of nutrition – autotrophs and heterotrophs
- Body organization -unicellular or multi-cellular
- Phylogenetic or evolutionary relationship
THE FIVE KINGDOM SYSTEM OF CLASSIFICATION
The Five kingdom system of classification are Monera, Protista, Fungi, Plantae and Animalia.
THE KINGDOM OF PROKARYOTES
This kingdom includes all prokaryotic organisms i.e. mycoplasma, bacteria, actinomycetes (filamentous bacteria) and cyanobacteria (blue-green Algae). They show the following characters.
- they’re microscopic. they are doing not possess a real nucleus. They lack membrane sure organelles. Their mode of nutrition is plant or heterotrophic. Some bacterium area unit plant and area unit chemical change. i.e. they’ll synthesize their organic food within the presence of daylight e.g. Spirillum. Some bacterium area unit chemosynthetic i.e. they’ll synthesize their organic food by explanation energy from some chemical reactions. E.g. bacteria genus and bacteria genus.
- several alternative bacteria like Rhizobium, Azotobacter and clostridia will fix part atomic number 7 into ammonia. This development is termed Biological organic process.
- Some bacteria are parasites and others live as symbionts.
- Some monerans like Archaebacteria can live in extreme environmental conditions like an absence of oxygen (anaerobic), high salt condition, high temperature like 800c or above and highly acidic soils.
- KINGDOM PROTISTA
This kingdom includes eukaryotic unicellular mostly aquatic cells. The show the following characters.
- They have a typical Eukaryotic cell organization.
- They typically bear cilia or flagella for locomotion. Most of them are photosynthetic autotrophs. They kind the chief producers of food in oceans and in H2O. All animate thing plants square measure together referred to as phytoplankton and animate thing animals as zooplankton. Phytoplanktons square measure photosynthetically active and have a cell membrane.
- Zooplanktons are mostly predatory. They lack a cell wall and show a holozoic mode of nutrition as in Amoeba.
- Some protists are parasitic. Some are symbionts while others are decomposers. Euglena, a protozoan has two modes of nutrition. In the presence of sunlight it is autotrophic and in the lack of sunlight, it is heterotrophic. This means of nutrition is well-known as mixotrophic and therefore they structure a borderline among plants and animals and can be classified in both.
- KINGDOM FUNGI
As we know that this kingdom consists of puffballs, mushrooms, and bracket fungi etc. They have eukaryotic cell organization. They show the following characteristics.
- They are either unicellular or multi-cellular organism.
- Their mode of nutrition is heterotrophic since they lack the inexperienced pigment chlorophyll. Some fungi like Puccinia square measure parasites whereas others like mould square measure saprotrophic and go after the dead organic matter.
- Their body is made up of numerous filamentous structures called hyphae.
- Their cell wall is made up of chitin.
- KINGDOM PLANTAE
It includes all multi-cellular plants of land and water. Major groups of Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms belong to this kingdom. It shows the following characteristics.
- The cells have a rigid cell wall made up of cellulose.
- They show various modes of nutrition. Most of them are autotrophy since they have chlorophyll. Some plants are heterotrophy. For e.g. Cuscuta is a parasite. Nepenthes and Drosera are insectivorous plants.
- KINGDOM ANIMALIA
This kingdom includes all multi-cellular eukaryotic organisms. They are also referred to as metazoans. They show the following characteristic features.
- All animals show a heterotrophic mode of nutrition. They form the consumers of an ecosystem.
- They have contractibility of the muscle cells.
- They can transmit impulses due to the presence of nerve cells.
- Some groups of animals are parasites e.g. tapeworms and roundworms.
MERITS OF THE FIVE KINDOM CLASSIFICATION
- It shows the phylogenetic relationships among the organisms.
- It is based on the complexity of the cell structure from prokaryotic to eukaryotic cell organization.
- It is based on the complexity of body organization from unicellular to multicellular.
- It is based on the modes of nutrition: autotrophic or heterotrophic mode of nutrition.
DEMERITS OF FIVE KINGDOM CLASSIFICATION
- Chlamydomonas and Chlorella are included under the kingdom Plantae. They should have been included under kingdom Protista since they are unicellular.
- Animal protozoans are not included along with animals.
- Animal protozoans are incorporated under the kingdom Protista which consist of unicellular plants. They give you an idea about different modes of diet.
- Yeasts, despite the fact that unicellular eukaryotes are not positioned in the kingdom Protista.