Five Kingdom Classification: Types, Features and Examples

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Five Kingdom Classification

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The five-kingdom classification was introduced after the two-kingdom classification. The two-kingdom classification was proposed by Swedish biologist Carolus Linnaeus which included both animal and plant kingdoms. However, two-kingdom classification was insufficient and could not differentiate organisms on the basis of cell structure complexity (prokaryotes and eukaryotes) and cell type (unicellular and multicellular). Later, R.H Whittaker in the year 1969 proposed the most accepted system of classification which are as follows:

1. Kingdom Monera
2. Kingdom Protista
3. Kindom Fungi
4. Kingdom Plantae
5. Kingdom Animalia

Kingdom Classification

Kingdom Monera

Kingdom Monera Includes all unicellular prokaryotic organisms. Examples of kingdom monera include Eubacteria, Archebacteria, Actinomycetes, Cyanobacteria, etc.

Features of Monera

• They are prokaryotic organisms which means they lack a true nucleus.
• They lack chloroplasts and other organelles but possess a cell wall. 
• Monerans are either heterotrophic or autotrophic. 
• They are green, and filamentous, with no visible structure inside the cells.
• No visible feeding mechanism exists in monerans.
• They absorb nutrients via cell walls or generate their own through photosynthesis.
• Respiration can be anaerobic or aerobic.

Types of Monera

Archaebacteria, Eubacteria, and Cyanobacteria are the three types of Monera. 

Archaebacteria:

​These are some of the oldest living bacteria that can survive both in the presence and absence of oxygen.

• Archaebacteria can survive even in adverse habitats.
• They are also called methanogens as they can produce methane.

Cyanobacteria:

Cyanobacteria are the types of bacteria that can produce their own food using sunlight.

• Cyanobacteria helps in nitrogen fixation of the soil to promote plant growth. 
• They are also known as ‘blue-green’ algae. 

Eubacteria:

They are unicellular prokaryotes and are called ‘true bacteria’.

• These bacteria are locomotive and contain a flagella for locomotion.
• Eubacteria reproduce either by binary fission or budding. 

Kingdom Protista

Protista are eukaryotic organisms. These organisms exist even before plants, animals, and fungi.

Features of Protista

• Protista are single-celled organisms that move using cilia, flagella, or amoeboid mechanisms.
• They lack a cell wall. However, few might possess it. 
• Reproduction involves the fusion of gametes and zygote formation.
• They possess a nucleus, chloroplast, and other organelles.
• Photosynthesis is used to obtain nutrients.
• They can be dissected using a microscope or a magnifying glass.

Types of Protista

Protista is sub-divided into the following types:

• Chrysophytes: They are golden-brown organisms usually found in freshwater and aquatic habitats.
• Dinoflagellates: They are unicellular organisms that are found in all aquatic habitats like brackish water, freshwater, marine water, etc. 
• Euglenoids: These organisms are present in freshwater. They possess a protein-rich (pellicle) cell wall and two flagella for movement.
• Slime Moulds: They are saprophytic, meaning they absorb the dissolved organic matter in the soil for nourishment.
• Protozoans: Heterotrophic organisms are the protozoans. They feed on carbon-rich organic matter and can be parasitic or free-living.

Kingdom Fungi 

Kingdom fungi include all eukaryotic organisms like yeasts, molds, and mushrooms.

Features of Fungi

• Fungi are multicellular organisms that possess a cell wall, organelles, and a nucleus.
• These organisms contain long thread-like structures called hyphae. The group of hyphae is the mycelium.
• They are not green in color as they lack chlorophyll pigment. 
• Fungi do not have locomotion mechanisms.
• The main component of reserved food in fungi is glycogen.
• Most fungi are saprophytic or heterotrophic. 
• The cell wall is composed of chitin and polysaccharides.
• They absorb nutrients from dead and decaying matter.

Types of Fungi

On the basis of reproduction, fungi are classified into four main types:

• Phycomycetes: The lowest class of fungi is the phycomycetes. They are present in plants, animals, soil, fruits, etc.
• Ascomycetes: These are the fungi that reproduce sexually via spores called ascospores.
• Basidiomycetes: Agaricus, bracket fungi, and puffballs are examples of basidiomycetes. They reproduce sexually via basidiospores.
• Deuteromycetes: These are also called fungi imperfecti and reproduce mostly by asexual mode of reproduction.

Kingdom Plantae

Plants, trees, flowers, liverworts, ferns, and mosses all belong to Kingdom Plantae.

Features of Plantae

• Plants are multicellular eukaryotic organisms. 
• Most types of algae as well as angiosperms, gymnosperms, and bryophytes, belong to this category.
• Nucleus and chloroplasts are present.
• Cell wall is present which is composed of cellulose.
• They can be heterotrophic as well as autotrophic.
• Organisms belonging to this group are non-motile.

Kingdom Animalia

Kingdom Animalia comprises all invertebrates and vertebrates. They are multicellular eukaryotic organisms.

Features of Animalia

• They have the ability to move.
• These organisms reproduce by fusion of male and female gametes.
• Animals obtain nutrients through ingestion also called holozoic nutrition.
• Fishes, amphibians, reptiles, snails, earthworms, mammals are all examples of animalia kingdom.

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Advantages of Five Kingdom Classification

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The advantages of five kingdom classification are as follows:

• Kingdom Monera contained all prokaryotic species. Therefore, they were segregated from all others as they differ in genetic, cellular, reproductive, and physi­ological organization.
• The unicellular eukaryotes, which include both plants and animals, were classified under Kingdom Protista. 
• Fungi are not related to plants and differ in functions and structure. Hence, all fungi were grouped under one kingdom. 
• The classification of the five kingdoms is based on early organizational and nutritional levels which were established in later groups that exist today.
• It is a more natural and systematic classification when compared to the two-kingdom type. 

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Disadvantages of Five Kingdom Classification

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The following are the disadvantages of five kingdom classification: 

• Identifying unicellular and multicellular organisms in algae is impossible. Whittaker did not include unicellular green algae in the Kingdom Protista as a result of this.
• It's difficult to keep each group together because they have so many differences. Monera and Protista, for example, include organisms with and without walls, photosynthetic and non-photosynthetic organisms, and unicellular and filamentous or mycelial organisms.
• Viruses are not classified under this system. 
• Archaebacteria differ in structure, chemistry, and physiology from other bacteria.
• Though classified as prokaryotes, mycoplasmas are distinct from bacteria.

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Things to Remember

• The classification of plants and animals into groups based on their observed similarities and differences is called classification.
• The science of identifying, classifying, and describing organisms is called a taxonomy.
• Kingdom classification is the highest level of classification into which organisms are classified in taxonomy. It is ranked higher than the phylum.
• Plant and animal kingdoms were the two types of kingdom proposed by Carolus Linnaeus in 1758.
• The basic unit of classification is the species. Organisms belonging to the same species have similar characteristics and can breed with one another to produce fertile offspring.

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Previous Years Questions

1. Meiosis takes place in...[NEET 2013]
2. The sexual reproduction is absent in….[NEET 1995]
3. For union between stock and scion in grafting which one is the first to occur….[NEET 1990]
4. A clone is ......… [KCET 2011]
5. Animals which possess cleidoic eggs exhibit….[KCET 2011]
6. Which among these is not a post fertilization event ?...[KCET 2016]
7. Type of asexual reproduction found in Hydra is..[KEAM]
8. Which of the following is having longitudinal binary fission ?….[KEAM]
9. In grafting, the stock and scion should be joined….
10. The mode of asexual reproduction in Euglena is….[CUCET 2010]
11. Isogamy is found in...[CUCET 2010]
12. In these plants artificial vegetative reproduction is possible through….[GUJCET 2006]
13. Apomixis in plant means development of a plant… [BHU UET 2008]
14. Which one of the following plants reproduces vegetatively by epiphyllous buds?

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