FIVE KINGDOMS CLASSIFICATION
Introduction
- Presently, the planet Earth is home to more than 8 million species, and continuously the new ones keep being discovered.
- Numerous scientists have tried to classify these living organisms for centuries.
- In the 19th and 20th centuries, the observation by the Greek philosopher Aristotle was expanded. Around 2400 years ago, Aristotle suggested that the planet’s biodiversity was either of animals or can be described as a classification of kingdom Plantae.
- Other biologists like Ernst Haeckel, Robert Whittaker, and Carl Woese also tried to classify living organisms into different Kingdoms.
- New kingdoms were discovered, and eventually, the Five Kingdom Classification was given.
Classification: classification is a scheme by which various organisms are arranged according to the relationship between the individuals and groups.
- In 1969, R. H. Whittaker proposed a five kingdom classification scheme that has been widely accepted universally.
- These five kingdoms are:
- Monera
- Protista
- Fungi
- Plantae
- Animalia
- Viruses are non-cellular molecular particles that remain on the threshold of life between living and non-living viruses are not included in any of these kingdoms and are treated as a separate group.
- The organisms are divided into the five kingdoms based on their general features like:
- Cell type: Organisms can have either prokaryotic cells (cells lacking membrane) and be prokaryotes or have eukaryotic cells (a membrane covers genetic material) and be eukaryotes. The kingdom Monera is the only kingdom that consists of prokaryotes, as the other four kingdoms have eukaryotic organisms.
- Cell wall: The kingdoms Monera, Fungi, and Plantae consist of organisms that have cell walls in their cells. Some of the Protists also have cell walls. But, the cells of the organisms of the Animalia kingdom do not have cell walls.
- Nuclear membrane: The organisms under the Protists kingdom have cells without a nuclear membrane, while the others have a nuclear membrane.
- Cell organization: This characteristic divides organisms into unicellular and multicellular.
- Nutrition mode: The Plantae kingdom consists of autotrophs, i.e., they make their food. Fungi and Animalia kingdom consist of heterotrophs, i.e., organisms under this kingdom depend on others for food. Monera and Protista consist of both- autotrophs and heterotrophs.
FIVE KINGDOMS
Kingdom Monera (prokaryota)
- It includes two major groups namely bacteria and cyanobacteria blue green algae.
- Habitat: Monerans are present in both living and non-living environment. Monerans are found everywhere in hot or thermal springs, in the deep ocean floor, under ice, in deserts and on or inside the body of plants and animals.
- Nutrition: They are autotrophic, i.e., they can synthesize food on their own while some others have a heterotrophic, saprophytic, parasitic, symbiotic, commensalistic and mutualistic modes of nutrition.
- Cell wall: Some have rigid cell walls, while some do not.
- Nucleus: Membrane bound nucleus is absent in monerans.
- Locomotion: With the help of flagella.
- Circulation: Through diffusion.
- Respiration: In these organisms vary few are obligate aerobes, while some are obligate anaerobes and facultative anaerobes.
- Reproduction: It is mostly asexual and few also reproduce by sexual reproduction. Usually the cells undergo reproduction by budding or binary fission.
- Examples: Mycobacterium, coli, Streptococcus etc.
Kingdom Protista
- The term “Protista” is derived from the Greek word “Protistos”, meaning “the very first”.
- They are simple, unicellular, eukaryotic organisms.
- Habitat: Most of the protists live in water, some in moist soil or even the body of human and plants.
- Nucleus: these organisms contain a nucleus which is bound to the organelles. Nuclei contain multiple DNA strands and the number of nucleotides is significantly less.
- Locomotion: Some of them even possess structures that aid locomotion like flagella or cilia.
- Respiration: Cellular respiration is the primarily aerobic process, but some living in the moist soil underneath ponds or in digestive tracts of animals are facultative anaerobes. mitochondria for cellular respiration and some have chloroplasts for photosynthesis.
- Nutrition: include both heterotrophic and autotrophic. Reproduction – Some reproduce sexually and others asexually.
- Some protists are pathogens of both plants and animals.
- Example: Plasmodium falciparum causes malaria in humans. Amoeba, Paramecium, Euglena.
Kingdom Mycota (Fungi)
- Habitat: The Kingdom Fungi grow best in an acidic environment.
- Morphology: Fungi are eukaryotic, non-vascular and non-motile organisms. The Kingdom Fungi consist of both unicellular (e.g. Yeast, Molds) and multicellular (e.g. mushrooms) organisms.
- The vegetative body of the fungi may be unicellular or composed of microscopic threads called hyphae.
- Cell wall: Like plant cells, fungi have cell walls made up of complex sugar molecules called chitin.
- Nutrition: They have a heterotrophic mode of nutrition. Few species are saprophytes i.e., they feed on dead and decaying organic matters. Some fungi are parasitic while some are symbionts. The growth rate of fungi is slower than that of bacteria. But unlike plants, they do not undergo photosynthesis.
- Reproduction: in fungi is both by sexual and asexual means.
- Examples: Mycorrhiza, Saccharomyces
Kingdom Plantae
- Morphology: Plants are multicellular organisms compared of eukaryotic cells.
- The cells are organized into tissues and have cell wall.
- They are primarily non-motile and live anchored to a substance.
- Nutrition: They obtain nutrients by photosynthesis and absorption.
- Reproduction: It is sexual and asexual.
- Examples: mosses, ferns, conifers and flowering plants.
Kingdom Animalia
- Morphology: Animals are multicellular organisms composed of eukaryotic cells. The cells are organized into tissue.
- Cell wall: lack cell wall.
- Nutrition: They do not carry out photosynthesis and obtain nutrients primarily by ingestion. Heterotrophic mode of nutrition.
- Locomotion: Many animals are adapted for locomotion.
- Reproduction: They reproduce by sexual mode of reproduction.
- Examples: sponges, worms, insects and vertebrates.
