Coupon Accepted Successfully!


Five Kingdom Classification

Five kingdom system of classification was postulated by R. H. Whittaker (1969). This type of classification includes five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. This classification was made based upon certain characters like cell structure, thallus organization, mode of nutrition, reproduction and phylogenetic relationships.

Kingdom Monera

  • Monera includes bacteria and other mostly tiny, single-celled organisms whose genetic material is loose in the cell.
  • Monera includes most organisms with a prokaryotic cell organization (ie , without a nucleus).
  • Bacteria occur everywhere (universal in distribution.) They are microscopic in nature.
  • Most bacteria fall into one of the four basic shapes they are spherical (coccus), rod (bacillus), comma (vibrium) and spiral (spirillum).
  • Bacteria show both autotrophic and heterotrophic mode of nutrition, (not able to prepare their own food and derive their energy from external source).
  • Monera has since been divided into Archaebacteria and Eubacteria.

Types of Bacterium


  • Archaea, like bacteria, are prokaryotes and have no true nucleus or any other organelles within their cells.
  • Other aspects of archaean biochemistry are unique - the presence of special type of cell wall which helps to withstand extreme conditions.
  • Initially, archaea were seen as extremophiles that lived in harsh environments, such as hot springs (thermoacidophiles) and salt-tolerant archaea (halophiles) and those living in high methane habitats like marshlands (methanogens).
  • Archaea have some importance in technology, with methanogens used to produce biogas and as part of sewage treatment, and enzymes from extremophile archaea that can resist high temperatures and organic solvents are exploited in biotechnology.

Eubacteria - eg: Thermophiles


  • Bacteria are a large group of unicellular micro-organisms.
  • Typically a few micrometres in length, bacteria have a wide range of shapes.
  • Bacteria are ubiquitous (present in every habitat on Earth), growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and in the live bodies of plants and animals.
  • There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of freshwater;
  • Bacteria are vital in recycling nutrients, with many important steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere (eg: Rhizobium, Nostoc) and putrefaction.  Bacteria that are photoautotrophic use light energy to convert carbon dioxide into useful molecules for the cell. A good example of photoautotrophic pathway is photosynthesis.
  • Chemoautotrophic bacteria generally use inorganic chemicals as their source of energy. This energy is achieved by oxidation/reduction reactions often involving metal ions. The energy is used to convert carbon dioxide into the molecules needed for life.
  • Although the vast majority of these bacteria are rendered harmless by the protective effects of the immune system, and a few are beneficial, some are pathogenic bacteria and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague.
  • The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa.

Rhizobium in the Root Nodules of Legume




  • Protists belong to diverse group of eukaryotic microorganisms.
  • The term protista was first used by Ernst Haeckel in 1866. Protists were traditionally subdivided into several groups based on similarities as Chrysophytes, Dinoflagellates, Euglenoids and Slime moulds.
  • Protists do not have much in common besides a relatively simple organization -- either they are unicellular, or they are multicellular without specialized tissues. This simple cellular organization distinguishes the protists from other eukaryotes, such as fungi, animals and plants.
  • Protists live in almost any environment that contains liquid water. Many Protists, such as algae, are photosynthetic and are vital primary producers in ecosystems, particularly in the ocean as part of the plankton.
  • Other Protists, such as the Kinetoplastids and Apicomplexa are responsible for a range of serious human diseases, such as malaria and sleeping sickness.


  • The golden algae or chrysophytes are a large group of heterokont algae, found mostly in freshwater.

Chrysophytes - Golden Algae

  • ​Most members are unicellular flagellates, with either two visible flagella, as in Ochromonas, or sometimes one, as in Chromulina.


  • Some members are generally amoeboid, with long branching cell extensions, though they pass through flagellate stages as well. Chrysamoeba and Rhizochrysis are typical of these.
  • Diatoms are a major group of chrysophytes (eukaryotic algae) and are one of the most common types of phytoplankton.
  • A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon dioxide) called a frustule.
  • These frustules show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides with a split between them, hence the group name.
  • Fossilized remains of diatoms over a billion of years forms Diatomaceous earth.



  • The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well.
  • Their populations are distributed depending on temperature, salinity, or depth. About half of all dinoflagellates are photosynthetic.
  • Most dinoflagellates are unicellular forms with two flagella; one of these extends towards the posterior, called the longitudinal flagellum, while the other forms a lateral circle, called the transverse flagellum.
  • Red tide is more specifically produced when dinoflagellates are able to reproduce rapidly and copiously on account of the abundant nutrients in the water. Although the resulting red waves are a miraculous sight, they, again, contain toxins that not only affect all marine life in the ocean but the people who consume them as well. A specific carrier is shellfish. This can introduce both non-fatal and fatal illness (due to the toxins they produce).

Dinoflagellates eg: Noctiluca


  • The euglenoids were first defined by Otto Bütschli in 1884 as the flagellate order Euglenida. Botanists subsequently treated the algal division Euglenophyta; thus they were classified as both animals and plants, as they share characteristics with both.
  • The euglenoids are one of the best-known groups of flagellates, commonly found in freshwater especially when it is rich in organic materials. Eg: Euglena.

Euglenoids eg: Euglena viridis

  • Many euglenoids have chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis or strictly by diffusion.
  • Euglenoids are distinguished mainly by the presence of a pellicle, which is composed of proteinaceous strips underneath the cell membrane, supported by dorsal and ventral microtubules.
  • This varies from rigid to flexible, and gives the cell its shape, often giving it distinctive striations. In many euglenoids the strips can slide past one another, causing an inching motion called metaboly. Otherwise they move using the flagella.

Slime Mould

  • Slime moulds feed on microorganisms in decaying vegetable matter. They can be found in the soil, on lawns, and in the forest commonly on deciduous logs. They are also common on mulch or even in leaf mould which inhabits ditches.

Slime Mould

Fruiting Bodies of Slime Mould

  • They begin life as Amoeba-like cells. These unicellular Amoeba-like are commonly haploid and multiply if they encounter their favorite food, bacteria.
  • These amoebae can mate if they encounter the correct mating type and form zygotes which then grow into Plasmodia which contain many nuclei without cell membranes between them, which can grow to be meters in size.
  • When the food supply wanes, the Plasmodium will migrate to the surface of its substrate and transform into rigid fruiting bodies.
  • The fruiting bodies or sporangia are what we commonly see, superficially look like fungi or moulds but they are not related to the true fungi. These sporangia will then release spores which hatch into amoebae to begin the life cycle again.

Protozoa are unicellular eukaryotes, (singular protozoan). While there is no exact definition of the term, most scientists use protozoan to refer to a unicellular heterotrophic protists, like Amoeba and Ciliates. Different types of protozoans are discussed below:

Protozoans - Unicellular life forms that mainly consist of contractile vacuoles, a nucleus, and cytoplasm as their basic structure. They move and feed by means of temporary cytoplasmic projections, called pseudopodia (false-feet). The most famous organism is Amoeba proteus.

Amoeba proteus

Sporozoans: Most members have a complex life-cycle, involving both asexual and sexual reproduction. Typically, a host is infected via an active invasion by the parasites, which divide to produce sporozoites that enter its cells. Eventually, the cells burst, releasing merozoites which infect other new cells e.g.: Plasmodium vivax causing malaria fever.

Ciliated Protozoans: Ciliates tend to be large Protozoa, a few reaching 2 mm in length, and are some of the most complex in structure. The name ciliate comes from the presence of hair-like locomotory organelles called cilia, which are identical in structure to flagella.

Most ciliate cell membranes are surrounded by a pellicle - a clear, elastic layer of protein. With a few exceptions, there is a distinct cytostome or mouth where ingestion takes place.


Flagellated Protozoans: Flagellates are protozoans (animal-like Protists). Eukaryotic flagella are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body or kinetosome, with microtubule roots that are an important part of the cell's brain. In some, for instance, they support a cytostome or mouth, where food is ingested. The flagella often support hairs, called mastigonemes, or contain rods. Their ultra structure plays an important role in classifying eukaryotes. E.g.: Trypanosoma.


Kingdom Fungi

The fungi are more closely related to animals than plants, yet the discipline of biology devoted to the study of fungi, known as mycology, often falls under a branch of Botany. A fungus is a eukaryotic and heterotrophic organism possessing a chitinous cell wall. Many fungi grow as thread-like filamentous microscopic structures called hyphae, and an assemblage of intertwined and interconnected hyphae is called a mycelium. Hyphae can be septate, i.e., divided into hyphal compartments separated by a septum, each compartment containing one or more nuclei or can be coenocytic, i.e., lacking hyphal compartmentalization. The reserve food material is glycogen.

The majority of species grow as multicellular filaments called hyphae (eg: Penicillium) forming a mycelium; some fungal species also grow as single cells (e.g. yeast). Occurring worldwide, most fungi are largely invisible to the naked eye, living for the most part in soil, dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in all ecosystems in decomposing organic matter and are indispensable in nutrient cycling and exchange.

Many fungal species have long been used as a direct source of food, such as mushrooms and truffles and in fermentation of various food products, such as wine, beer, and soya sauce. Some fungi become noticeable when fruiting, either as mushrooms or moulds. More recently, fungi are being used as sources for antibiotics used in medicine and various enzymes, such as cellulases, pectinases, and proteases, important for industrial use or as active ingredients of detergents.

Many fungi produce bioactive compounds called mycotoxins. Several species of the fungi are significant pathogens of humans and other animals, and losses due to diseases of crops (e.g., blast disease of rice) or food spoilage caused by fungi can have a large impact on human food supply and local economies.

Specialized fungal structures important in sexual reproduction are the apothecia, perithecia, and cleistothecia in the ascomycetes, and the fruiting bodies of the basidiomycetes, and a few ascomycetes. These reproductive structures can sometimes grow very large, and are well known as mushrooms.

Some species have lost the ability to form specialized reproductive structures, and propagate solely by vegetative growth. Yeasts, moulds, and mushrooms are examples of fungi.

Phycomycetes: A group of thallophytic plant-like organisms of low organization, destitute of chlorophyll, in which reproduction is mainly accomplished by means of asexual spores, which are produced in a great variety of ways, though sexual reproduction is known to occur in certain (phycomycetes), or so-called algal fungi. They include the molds, mildews, rusts, smuts, mushrooms, toadstools, puff balls, and the allies of each.

In phycomycetes asexual reproduction takes place by producing zoospores (with flagella), or by aplanospores (without flagella). The former one is motile and the latter is non-motile.

These spores are produced inside a special sac like structure called sporangium.

Few Examples belonging to this group are Mucor, Rhizopus (bread mould) and Albugo (the parasitic fungi causing white rust disease).


(Note: Fungi appear to have originated by degeneration from various algae losing their chlorophyll on assuming a parasitic or saprophytic life.)

Ascomycota is a Division /Phylum of Fungi, and sub-kingdom Dikarya, whose members are commonly known as Sac Fungi. Common examples are Neurospora sps.

Characteristically, when reproducing sexually, they produce non-motile spores in a distinctive type of microscopic cell called an "ascus".These spores are called ascospores. However, some members of the Ascomycota do not reproduce sexually and do not form asci or ascospores.

This monophyletic grouping is an extremely significant and successful group of organisms. Familiar examples of sac fungi include morels, truffles, brewer's yeast and baker's yeast, cup fungi, and the majority of lichens (loosely termed "ascolichens") such as Cladonia.



Brewer's Yeast

Many plant-pathogenic fungi belong to the Ascomycota. Commonly seen examples include apple scab, ergot, black knot, and the powdery mildews. Species of ascomycetes are also popular in the laboratory. Sordaria fimicola, Neurospora crassa and several species of yeasts are used in many genetics and cell biology experiments. Penicillium species on cheeses and in the antibiotic industry are examples of asexual taxa, otherwise known as anamorphs, which belong to the Ascomycota.

Apart from exceptions such as baker's Yeast (Saccharomyces cerevisiae), almost all fungi of the Ascomycota are haploid, so their nuclei only contain one set of chromosomes, which makes them especially susceptible to mutations. During sexual reproduction there is a diploid phase (with two sets of chromosomes), which as a rule is very short. Then meiosis occurs, generally very soon, so that the haploid state is re-established.

Unlike the process in animals and plants, after the union of the cytoplasm of the two gametangia (plasmogamy), the merging of the nuclei (karyogamy) does not usually occur immediately. Instead, the nuclei which have migrated pair up with the nuclei of the ascogonium but remain separate next to their partners. With this the dikaryophase of the life cycle begins; during this time the pairs of nuclei repeatedly synchronously divide, so that a great number of individuals are produced.


More specifically the Basidiomycota include mushrooms, puff balls, stink horns, bracket fungi, other polypores, jelly fungi, smuts, bunts, rusts, mirror yeasts, and the human pathogenic yeast, Cryptococcus. Basically, Basidiomycota are filamentous fungi composed of hyphae (except for those forming yeasts), and reproducing sexually via the formation of specialized club-shaped end cells called basidia that normally bear external spores (usually four ), which are specialized meiospores called basidiospores. However, some Basidiomycota reproduce asexually, and may or may not also reproduce sexually. Asexually reproducing Basidiomycota (discussed below) can be recognized as members of this phylum by gross similarity to others, by the formation of a distinctive anatomical feature (clamp connection).





The term is now used only informally, to denote species of fungi that are asexually reproducing members of the fungal phyla, Ascomycota and Basidiomycota.

Deuteromycetes are commonly called fungi imperfecti, or imperfect fungi. The deuteromycota do not fit into the commonly established taxonomic classifications of fungi that are based on biological species concepts or morphological characteristics of sexual structures, because their sexual form of reproduction has never been observed; hence the name "imperfect fungi." Only their asexual form of reproduction is known. This group of fungi produces their spores asexually.

There are about 25,000 species that have been classified in the deuteromycota. Fungi producing the antibiotic penicillin and those that cause athlete's foot and yeast infections are examples of imperfect fungi. In addition, there are a number of edible imperfect fungi, including the ones that provide the distinctive characteristics of Roquefort and Camembert cheese.

The Deuteromycota are classified as fungi for two main reasons. First, their multicellular tissue is similar to the hyphae of sac fungi and club fungi. Second, they have erect hyphae with asexual spores, called conidiophores, which are similar to those of the sac fungi and club fungi.

The best known fungus in this phylum is Penicillium. Some species in this genus appear as pathogenic, blue-green moulds on fruits, vegetables, and cheeses. Certainly the best known product from this genus is penicillin, the first widely-used antibiotic. Penicillin was first extracted from Penicillium notatum by Sir Alexander Fleming over 50 years ago, but is now known to be produced by many other species in this genus.

Penicillum notatum

Family Plantae

  • Organisms under this kingdom were all eukaryotic and multicellular.
  • Green plants containing chlorophyll pigment can prepare their own food using solar energy are called autotrophs. There are few other species which are heterotrophs like parasites (Cuscuta, Loranthus and Viscum) and insectivorous plants (Nepenthes, Drosera, Bladderwort and venus fly trap).
  • Kingdom Plantae includes Algae, Fungi, Bryophyts, Pteridophytes, Gymnosperms and Angiosperms (flowering plants). Among these plants first three belongs to non-vascular plants and the last three belongs to vascular plants.
  • Non-vascular plants lack a water-conducting system of tubular cells (called xylem tissue), and do not have true roots, stems and leaves. Like algae and fungi, the plant body of some non vascular plants is often called a thallus. Non-vascular plants are all placed in the Division Bryophyta, including the mosses and liverworts. The vast majority of the plant kingdom is vascular cryptogams with tubular, water-conducting cells called xylem tissue. Like a microscopic pipeline system, they are arranged end-to-end from the roots to the leaves. Unlike non-vascular plants, they have true roots, stems and leaves.
  • A clear alternation of generation is observed with the types of generations representing diploid sporophytic and haploid gametophytic phases in all vascular cryptogams and vice versa in Bryophytes. Among these one is dominant and independent, while the other one is recessive and dependent.

Viscum album



Kingdom Animalia

  • This kingdom includes multicellular, with specialized eukaryotic heterophic organisms (Major group of animals).
  • They have their own means of locomotion and growth is limited it stops at certain period of age.
  • All the animals are showing heterotrophic as they ingest their food (holozoic mode of nutrition).
  • Some common examples are sponges, worms, insects, fish, amphibians, reptiles, birds and mammals.
  • Asexual mode of reproduction is restricted to some of the lower forms and all the higher organism shows sexual mode of reproduction.
  • The sexual reproduction involves involving the fusion of male and female gametes resulting in zygote which undergoes embryonic stages of development and grow into an adult.

Test Your Skills Now!
Take a Quiz now
Reviewer Name