Biological Classification

Introduction
Life on Earth is thought to have begun around 3.7 billion years ago, based on fossil evidence. There are numerous species on the planet today, ranging from minuscule microorganisms to massive blue whales. Because life is so diverse, there are many species that have yet to be identified. For example, until an authentic specimen was documented on camera in 2004, the enormous squid (Architeuthis dux) was nothing more than a sailor's tall story.

Many organisms have yet to be identified or found in the same way. We do, however, require a method to classify the organisms that we are aware of. This is because, the same organism, or variants of it, may be found in multiple areas around the world. And these organisms are given different names depending on where they are found, despite the fact that they are all biologically the same organism.

Five Kingdom Classification

The Five Kingdom Classification is one of the most widely used methods for classifying living organisms based on features such as cell structure, body organization, manner of feeding, source of nutrition, reproduction, and interrelationship with other organisms. The five-kingdom classification was proposed by R. H. Whittaker in the year 1969, based on the work of prior biologists such as Carolus Linnaeus.

Whittaker’s classification

A living entity can be divided into five major kingdoms according to the 5 kingdom classification:

• Kingdom Monera
• Kingdom Protista
• Kingdom Fungi
• Kingdom Plantae
• Kingdom Animalia
  
  

Kingdom Monera

Bacteria are classified as members of the Monera Kingdom.

Characteristics of Monerans:

They have the following crucial characteristics:

• Bacteria are minute organisms that can be found almost anywhere.
• They are prokaryotic and have a cell wall.
• Amino acids and carbohydrates make up the cell wall.
• 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.
  
  

Monerans Bacteria are divided into four categories based on their shape:

• Coccus (plural: cocci) - This bacterium has a spherical form.
• Bacillus (plural: bacilli) — Bacilli are rod-shaped bacteria.
• Vibrium (plural: vibrio) — These bacteria have a comma-like form.
• Spirillum (plural: spirilla) — Spirillum bacteria have a spiral form.
  
  

Since then, Monera has been split into Archaebacteria and Eubacteria.

Kingdom Protista

Protista Characteristics:

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

• They are eukaryotic and unicellular creatures.
• For mobility, some of them contain cilia or flagella.
• Cell fusion and zygote formation are used in sexual reproduction.
  
  

Kingdom Protista classification:

Protista is divided into the following groups:

• Chrysophytes: This group includes golden algae (desmids) and diatoms. They live in both marine and freshwater environments.
• Dinoflagellates: They are often photosynthetic and saltwater organisms. Their colour is determined by the major pigments in their cells, which might be red, blue, brown, green, or yellow.
• Euglenoids: The majority of Euglenoids reside in freshwater habitats in still water. They lack a cell wall and instead have a protein-rich layer termed a pellicle.
• Slime Moulds: Saprophytic slime molds. The body glides along with decomposing leaves and twigs, feeding on organic matter. They form a clump in favorable conditions and are referred to as Plasmodial.
• Protozoans: Protozoans are heterotrophic organisms that can live as parasites or predators.
  
  

Kingdom Fungi

Molds, mushrooms, yeast, and other fungi are all members of the fungus kingdom. They have a wide range of uses in both household and commercial settings.

Fungi Kingdom Characteristics:

• The fungi, with the exception of yeast, are filamentous (single-celled).
• Hyphae are slender, long thread-like structures that make up their form. Mycelium refers to the web of hyphae.
• Unbroken tubes jam-packed with multinucleated cytoplasm make up some of the hyphae. Coenocytic hyphae is the name given to such hyphae.
• The other form of hyphae has septae or cross-walls.
• Polysaccharides and chitin make up the cell wall of fungi.
• The majority of the fungi are heterotrophic saprophytes.
• Some fungi live as symbionts with other organisms. Some of them are parasitic. Some symbiotic fungi, such as lichens, exist in association with algae. As mycorrhiza, some symbiotic fungi live in connection with the roots of higher plants.

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Kingdom Plantae

Features of Kingdom Plantae

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

Kingdom Animalia

Animalia's Characteristics

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

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