History of five kingdom classification

The five-kingdom classification that we observe today was not the original result of living organism classification. Carolus Linnaeus was the first to propose a two-kingdom categorisation, with just kingdom Plantae and kingdom Animalia included.

The two-kingdom classification lasted for a long time, but it did not persist indefinitely because it did not consider many important factors while classifying. There was no distinction between eukaryotes and prokaryotes, unicellular and multicellular organisms, photosynthetic and non-photosynthetic organisms, or photosynthetic and non-photosynthetic organisms in the biological world. Many organisms could not be classed as either plants or animals, so putting them all in one of the two kingdoms was not sufficient atall.

All of this complexity necessitated a new classification system that took into account cell structure, cell wall existence, mode of reproduction, and mode of nourishment. As a result, R H Whittaker devised the five-kingdom classification system.

Characteristics of Monerans

• Bacteria are minute organisms that can be found almost anywhere in the world.
• They are prokaryotic and have a cell wall in the body.
• Amino acids and carbohydrates make up the cell wall in the body.
• Bacteria can grow in both heterotrophic and autotrophic environments.
• The bacteria that live in heterotrophic environments might be parasitic or saprophytic. Chemosynthetic or photosynthetic autotrophic microorganisms are both possible so.

Protista Characteristics

The following are some of the most important characteristics of the Protista kingdom:

• They are eukaryotic and unicellular creatures in nature.
• For mobility, some of them contain cilia or flagella and use to move.
• Cell fusion and zygote formation are used in sexual reproduction in protista for ages.

Fungi Kingdom

Moulds, mushrooms, yeast, and other fungi are all members of the fungus kingdom and belong to it. They have a wide range of uses in both household and commercial settings in the real world.

Fungi Kingdom Characteristics

• The fungi, except yeast, are filamentous.
• Hyphae are slender, long thread-like structures that make up their form and Mycelium refers to the web of hyphae in the fungi kingdom.
• Unbroken tubes jam-packed with multinucleated cytoplasm make up some of the hyphae. Coenocytic hyphae are the name given to such hyphae.
• The other form of hyphae has septae or cross-walls in the fungi kingdom.

Plantae Kingdom Characteristics

• All eukaryotes having chloroplasts belong to the kingdom Plantae.
• The majority of them are autotrophic, although some are also heterotrophic in the kingdom.
• Cellulose makes up the majority of the cell wall in plant cells.
• Plants go through two stages in their life. These phases are in a back-and-forth relationship. The saprophytic phase is diploid, and the gametophytic phase is haploid in plants. The lengths of the diploid and haploid phases differ between different plant families in nature. This process is known as the Alternation of Generation in the kingdom.

Animalia’s Characteristics

• This kingdom encompasses all heterotrophic multicellular eukaryotes that lack a cell wall in the kingdom.
• Plants provide nourishment to animals either directly or indirectly in nature. Their feeding mode is holozoic in them. Holozoic feeding entails ingesting food and subsequently digesting it with the aid of an internal cavity in the animal.
• Many animals are capable of moving.

Conclusion

The five-kingdom classification of living organisms took many factors into account and remains the most efficient method to this day. The old categorization system was based on a single trait that was used to put two highly diverse organisms together. The presence of the cell wall, for example, was used to put fungi and plants together. 

Unicellular and multicellular organisms were classed together in the same way. 

As a result, all species were reclassified into the five kingdoms of the five-kingdom classification, beginning with Monera, which included all prokaryotic unicellular organisms. Following that, the kingdom Protista was created to house all eukaryotic unicellular creatures. The presence or absence of a cell wall was used to classify the organisms. The ones who didn’t have a cell wall were placed in the kingdom Animalia, while those that did had a cell wall were placed in the kingdom Plantae.

Plantae and fungi were divided into photosynthetic and non-photosynthetic kingdoms, which contained Plantae and fungi, respectively. This system of living entity classification is superior to the earlier classification of plants and animals because it eliminates the ambiguity of placing one species in two separate kingdoms.