Kingdoms are the second highest rank in biological taxonomy. There are traditionally six kingdoms - Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria. However, some systems use five kingdoms excluding Archaea/Archaebacteria. The document then discusses Aristotle's early two-kingdom system and Linnaeus' two-kingdom system. It introduces Whittaker's influential five kingdom system of Monera, Protista, Fungi, Plantae, and Animalia based on cell structure, nutrition, and other characteristics. Each kingdom is then described in more detail covering key defining features.

1. In biology, kingdom is the second highest taxonomic rank, justbelow domain.
Kingdoms are divided into smaller groups called phyla.
Traditionally, sometextbooks from the United States and Canada used a
systemof six
kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria,
and Bacteria/Eubacteria) .while textbooks in countries like Great Britain, India,
Greece, Brazil and other countries use five kingdoms
only (Animalia, Plantae, Fungi, Protista and Monera)
Aristotle’s classification (earliest system of classification) :
More than 2000 year ago Aristotle developed firstwidely accepted system of
biological classification
It was the earliest toattempt amore scientific basis
for classification.
He used simple morphologicalcharacters to classify
plants into trees, shrubs and herbs onthe basis of
habit.
HERB SHRUB TREE
1)-SOFT BODY
1)WOODY
2)TRUNK ABSENT
1)WOODY MAIN
STEM PRESENT
AND CALLED
TRUNK
He also divided animals into two groups, thosewhich had red blood and those
that did not.
ENAIMA ANAIMA
WithRBC Without RBC
Aristotle then divided each of these main groups into three smaller
groups Animal Subgroups--Land,Water,Air and Plant Subgroups---
Small, Medium, Large

2. TWO KINGDOM SYSTEM OF CLASSIFICATION :
Proposed by Carolus Linnaeus In his SystemaNaturae, first
published in 1735
He classifiedall living organisms into two kingdoms – on the basis
of nutrition and locomotion (mobility)-1)Plantae 2)Animalia
BASIS
•Nutrition
•Cell wall
•Locomotion
PLANTAE
•Autotroph
•Present
•Absent
ANIMALIA
•Heterotroph
•Absent
•present

3. Linnaeus divided the kingdoms into 4 more levels: class, order,
genus, and species.
Demerits :
(a) The two kingdom system of classification did not indicate any
evolutionary relationshipbetween plants and animals.
(b) It grouped togetherthe prokaryotes (bacteria, BGA) with other
eukaryotes.
PLANTAE
•Bacteria,Algae,Fungi,Bryophytes,Pteridophytes,Gymnosperms,Angeosperms
ANIMALIA
•Vertibrates and Invertibrates

4. (c) It also grouped unicellularand multi-cellularorganisms
together.
(d) This system did not distinguish the heterotrophic fungi and the
autotrophic green plants.
(e)Few organisms like Chlamydomonas sp. ,Euglena sp. ,Slime
mold share character of both plant and animals but not fixed
position.
Five Kingdom Classification :
Proposed by R.H. Whittaker (1969).
American Taxonomist,classifiedall organisms into fivekingdoms:
Monera , Protista, Fungi, Plantaeand Animal.

5. The main criteria for classification Cell structure, body organisation, modeof
nutrition, reproduction and phylogenetic relationships.
Criteriafor Five KingdomClassification
 Cell structureComplexity: prokaryotic and eukaryotic cells.
 The complexity of body structure or structuralorganization: unicellular
and multicellular.
 Nutrition Mode: photo-autotrophy (Plantae), absorptiveheterotrophy
(fungi), and ingestive heterotrophy (Animalia).
 Ecological lifestyle: producers (plantae), decomposers (fungi) and
consumers (animalia).
 Phylogenetic relationships: prokaryotes to eukaryotes, unicellular to
multicellular organisms.
KINGDOM MONERA
1. The kingdom Monera includes all prokaryotes— Bacteria are the sole
members of the Kingdom Monera.
2. They are the most abundantmicro-organisms. Bacteria occur almost
everywherelike extreme habitats such as hot springs, deserts, snow and
deep oceans wherevery few other life forms can survive. Many of them
live in or on other organisms as parasites.
3. Bacteria are
grouped under four
categories based on
their shape: the
sphericalCoccus
(pl.: cocci), the rod-
shaped Bacillus (pl.:
bacilli), the comma-
shaped Vibrium (pl.:
vibrio) and the
spiralSpirillum (pl.:
spirilla)
4. Some of the
bacteria are autotrophic, i.e., they synthesisetheir own food from

6. inorganic substrates. They may be photosynthetic autotrophic or
chemosynthetic autotrophic. The vastmajority of bacteria are
heterotrophs, i.e., they depend on other organisms or on dead organic
matter for food.
 Archaebacteria:
1)Thesebacteria live in most harsh habitats such as extreme salty
areas (halophiles), hot springs (thermoacidophiles) and marshy areas
(methanogens).

7. 2)Archaebacteria differ from other bacteria in having a different cell
wall structureArchaebacteria have cell membranes made of ether-
linked phospholipids, whilebacteria and eukaryotes both make their
cell membranes out of ester-linked phospholipids and this feature is
responsiblefor their survivalin extreme conditions.
Methanogens are present in the gut of severalruminantanimals
such as cows and
buffaloes and they are
responsiblefor the
production of methane
(biogas) from the dung of
these animals.
e.g,-Methanococcus
 Eubacteria: Most eubacteria are enclosed by a cellular wall, which
is made up of peptidoglycans in a cross-linked chain pattern
the presenceof a rigid cell wall, and if motile, a flagellum

8. The cyanobacteria(alsoreferred toas blue-greenalgae) have
chlorophyll a similar togreenplants and are photosynthetic
autotrophs .The cyanobacteria are unicellular, colonial or
filamentous, freshwater/marineor terrestrial algae. The colonies are
generally surrounded by gelatinous sheath. They often form blooms
in polluted water bodies. Some of these organisms can fix
atmospheric nitrogen in specialised cells called heterocysts, e.g.,
Nostoc and Anabaena.
Chemosynthetic
autotrophic bacteria
oxidise various
inorganic substances
such as nitrates,
nitrites and ammonia
and usethe released
energy for their ATP
production. They play a great role in recycling nutrients like nitrogen,
phosphorous, iron and sulphur.
e.g.- Nitrosomonas
Nostoc

9. Heterotrophic bacteriaare most abundant in nature The majority
are important decomposers. Many of them have a significant impact
on human affairs. They are helpful in making curd from milk,
production of antibiotics, fixing nitrogen in legume roots, etc. Some
are pathogens causing damage to human beings, crops, farm animals
and pets. Cholera, typhoid, tetanus,
citrus canker are well known
diseases caused by different
bacteria.
Bacteria reproducemainly by
fission . Sometimes, under
unfavourableconditions, they producespores called Endospore.
They also reproduceby a sortof sexual reproduction by adopting a
primitive type of DNA transfer from one bacterium to the other.
The Mycoplasmaare organisms that completely lack a cell wall.
They are the smallest living cells known and can survivewithout
oxygen. Many mycoplasma arepathogenic in animals and plants.
KINGDOM PROTISTA
 All single-celled eukaryotes
 Members of Protista are primarily aquatic

10.  The protistan cell body contains a well defined nucleus and other
membrane-bound organelles.
 Some have flagella or cilia
 Protists reproduceasexually and sexually by a process involving cell
fusion and zygoteformation
 Chrysophytes, Dinoflagellates, Euglenoids, Slimemoulds and
Protozoans under Protista
CHRYSOPHYTES:
This group includes diatoms and golden algae (desmids). fresh water as well as
in marine habitat. microscopic and float passively in water currents (plankton).
Most of them are photosynthetic.
In diatoms the cell walls form two thin
overlapping shells called theca, which fit
together as in a soap box. The walls are
embedded with silica and thus the walls
are indestructible. Thus, diatoms have left
behind large amount of cell wall deposits
in their habitat; this accumulation over billions of years is referred to as
‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils
and syrups. Diatoms arethe chief ‘producers’ in the oceans.
Dinoflagellates
These organisms aremostly marine and photosynthetic. They appear yellow,
green, brown, blueor red depending on the main pigments presentin their
cells.

11. The cell wall has stiff cellulose plates on the outer surface. Mostof them have
two flagella; one lies longitudinally and the other transversely in a furrow
between the wall plates.
Very often, red
dinoflagellates (Example:
Gonyaulax) undergo such
rapid multiplication that
they make the sea appear
red (red tides).
Toxins released by such
large numbers may even
kill other marineanimals
such as fishes.
Slime Moulds Slime moulds are saprophytic protists. Thebody moves along
decaying twigs and leaves engulfing organic material. Under suitable
conditions, they form an
aggregation called
plasmodium which may
grow and spread over
severalfeet. During
unfavourableconditions,
the plasmodium
differentiates and forms
fruiting bodies bearing
spores at their tips. The
spores possess true
walls. They are
extremely resistantand survivefor many years, even under adverse
conditions. The spores aredispersed by air currents.
Protozoans All protozoans areheterotrophs and live as predators or parasites.
They are believed to be primitive relatives of animals. There are four major
groups of protozoans.

12. Amoeboidprotozoans: Theseorganisms live in fresh water, sea water or moist
soil. They moveand capture their prey by
putting out pseudopodia (false feet) as in
Amoeba. Marine forms havesilica shells on their
surface. Someof them such as Entamoeba are
parasites.
Flagellatedprotozoans: Themembers of this group are either free-living or
parasitic. They have
flagella. The parasitic
forms cause
diaseases such as
sleeping sickness.
Example:
Trypanosoma.
Ciliatedprotozoans: Theseare aquatic, actively moving organisms becauseof
the presenceof thousands
of cilia. They have a cavity
(gullet) that opens to the
outside of the cell surface.
The coordinated
movement of rows of cilia
causes the water laden
with food to be steered
into the gullet. Example:
Paramoecium

13. Sporozoans: This includes diverseorganisms thathave an infectious spore-like
stage in their life cycle. The most notorious is Plasmodium (malarial parasite)
which causes malaria, a disease which has a staggering effect on human
population.
KINGDOM FUNGI
 heterotrophic organisms
 Exception of yeasts (unicellular), fungiare filamentous.
 Their bodies consistof long slender thread-like structures called hyphae
 The network of hyphaeis known as mycelium. Some hyphaeare
continuous tubes filled with multinucleated cytoplasm with out septa–
these are called coenocytic hyphae. Some haveseptae or cross walls in
their hyphae
 The cell walls of fungiare composed of chitin and polysaccharides
 Most fungiare heterotrophic and absorb solubleorganic matter from
dead substrates and hence are called saprophytes.
 Those that depend on living plants and animals are called parasites.
 They can also live as symbionts – in association with algae as lichens and
with roots of higher plants as mycorrhiza
 Puccinia causewheat rust. penicillium is sourceof antibiotics
 Reproduction in fungican take place by
1)vegetative means – [fragmentation, fission and budding. ]
2)Asexualreproduction [ by spores called conidia or sporangiospores or
zoospores]
3)sexualreproduction [is by oospores, ascospores and basidiospores.]
The sexual cycle involves the following three steps:
(i) Fusion of protoplasms between two motile or non-motile gametes
called plasmogamy. (ii) Fusion of two nuclei called karyogamy.
(iii) Meiosis in zygoteresulting in haploid spores.
When a fungus reproduces sexually, two haploid hyphaeof compatible
mating types come together and fuse. In somefungi the fusion of two
haploid cells immediately results in diploid cells (2n). However, in other
fungi (ascomycetes and basidiomycetes), an intervening dikaryotic stage

14. (n + n, i.e., two nuclei per cell) occurs; such a condition is called a
dikaryon and the phaseis called dikaryophaseof fungus.
Phycomycetes phycomycetes arefound in aquatic habitats and on
decaying wood in moist and damp places or as obligate parasites on
plants. The mycelium is aseptate and coenocytic. Asexual reproduction
takes place by zoospores (motile) or by aplanospores (non-motile).
zygosporeis formed by fusion of two gametes. These gametes are
similar in morphology (isogamous) or dissimilar (anisogamousor
oogamous).
Some common examples are Mucor , Rhizopus (the bread mould
mentioned earlier) and Albugo (the parasitic fungion mustard).
AscomycetesCommonly known as sac-fungi, theascomycetes are
mostly multicellular, e.g., Penicillium, or rarely unicellular, e.g., yeast
(Saccharomyces). They aresaprophytic, decomposers, parasitic or
coprophilous (growing on dung).
Mycelium is branched and septate.
The asexual spores are conidia
produced exogenously on the
special mycelium called
conidiophores. Conidia on
germination producemycelium.
Sexual spores arecalled
ascospores which areproduced
endogenously in sac like asci
(singular ascus. asciarearranged

15. in different types of fruiting bodies called ascocarps. Someexamples are
Aspergillus, Neurospora.
BasidiomycetesCommonly known formsof basidiomycetes are
mushrooms, bracketfungior puffballs. They grow in soil, on logs and
tree stumps and in living plant bodies as parasites, e.g., rusts and smuts.
The mycelium is branched and septate. The asexual spores aregenerally
not found, but vegetative reproduction by fragmentation is common.
The sex organs are absent,
but plasmogamy is brought
about by fusion of two
vegetative or somatic cells
of different strains or
genotypes and formation of
dikaryotic which ultimately
gives rise to basidium.
Karyogamy and meiosis
take place in the basidium
producing four basidiospores. Thebasidiospores areexogenously
produced on the basidium (pl.: basidia).
The basidiaare arrangedin fruiting bodies calledbasidiocarps.
Some common members are Agaricus(mushroom) , Ustilago (smut) and
Puccinia (rustfungus).
Deuteromycetes Commonly known as imperfectfungi becauseonly the
asexual or vegetative phases of these fungiare known. The
deuteromycetes reproduce
only by asexual spores known
as conidia. The mycelium is
septate and branched. Some
members are saprophytes or
parasites while a large number
of them are decomposers of
litter and help in mineral
cycling. Some examples are Alternaria, Colletotrichum and Trichoderma.
Conidia

16. KINGDOM PLANTAE
 all eukaryotic chlorophyll-containing organisms commonly called plants.
A few members are partially heterotrophic such as the insectivorous
plants or parasites. and Cuscuta is a parasite.
 The plant cells have an eukaryotic structurewith prominentchloroplasts
and cell wall mainly made of cellulose.
 Plantae includes algae, bryophytes, pteridophytes, gymnosperms and
angiosperms.
 Life cycle of plants has two distinct phases – the diploid sporophytic and
the haploid gametophytic –ie present of alternation of generation
KINGDOM ANIMALIA
 heterotrophic ,multicellular,eukaryotic organisms thatlack cell walls.
 Their mode of nutrition is holozoic – by ingestion of food
 Higher forms show elaboratesensory and neuromotor mechanism.
 Most of them are capable of locomotion. The sexual reproduction is
by copulation of male and female followed by embryological
development
Advantage of Whittaker’s Five Kingdom
1. The first and most important advantageis, this five-kingdom
classification differentiates the prokaryotes into a separatekingdom
called monera. Because the prokaryotes arediffer from their genetic,
cellular, reproductive, and physiologicalorganization.
2. Whittaker’s FiveKingdom classification separates the fungiinto a
separate kingdom, which separates them from plants. The fungi has
distinct biochemical, physiologicaland structuralorganization.
3. There were presentseveral unicellular eukaryotes that had been
included both amongstplants and animals, which creates a big problem.
This classification separates the unicellular eukaryotes into the kingdom
Protista, this helps us to distinguish them separately.

17. 4. The 5 kingdom classification relies on ranges of organization and
nutrition which developed very early and have become established in
later groups which mightbe presentin the present day.
5. In five kingdom classification, the plant and animal and plant kingdoms
are more homogeneous as compared to two-kingdom classification.
6. The Whittaker’s Five Kingdom classification bring out the phylogenetic
relationships even between the primitive forms.
Limitations of Whittaker’s Five Kingdom
1. This Five Kingdom classification can not differentiate between
unicellular and multicellular algae, because Whittaker doesn’tinclude
the unicellular green algae in the kingdom Protista.
2. Viruses arenot included in this Five Kingdom classification.
3. Archaebacteria differ in their structure, composition, and physiology
frombacteria.
4. It’s hard to keep each group together because each group has different
variations. Such as, monera and protista contain both walled and wall-
less organisms, photosynthetic and non-photosynthetic organisms,
unicellular and filamentous or mycelial organisms.
5. Mycoplasmas areplaced along with prokaryotes, butthey are different
frombacteria.
6. Some biologists do not agree that algae and protozoa belonged to the
same kingdom.
7. This five kingdom classification does not include the symbiotic
associations. For example, lichens are a symbiotic association between
fungi and algae