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BIOLOGICAL CLASSIFICATION
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 Aristotle’s classification
• Aristotle was the earliest to attempt a more scientific basis for classification
of organisms.
• He classified plants to trees, shrubs & herbs and animals into 2 groups, those
with red blood and without red blood.

Mammals,
Red Blood lizards, birds,
fish

ANIMALS
Hard bodied insects
No Red
Blood Shell Shellfish
Soft bodied
No shell Jellyfish

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 Two-Kingdom classification
• It is proposed by Linnaeus (1758).
• This system classifies organisms into Two Kingdoms- Plantae & Animalia.

Kingdom
Plantae
Organisms
Kingdom
Animalia
 Two-Kingdom classification
Drawbacks of 2-kingdom classification
• Prokaryotes (Bacteria, cyanobacteria) & eukaryotes
(fungi, mosses, ferns, gymnosperms & angiosperms)
were included under ‘Plants’ based on the presence of
cell wall. But they are widely differed in other features.

• It included unicellular & multicellular organisms in

same group. E.g. Chlamydomonas & Spirogyra were
placed under algae. Chlamydomonas Spirogyra

• It did not differentiate between heterotrophic fungi

and autotrophic green plants. Fungi have chitinous cell
wall while the green plants have cellulosic cell wall.
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 Five-Kingdom classification
• It is proposed by R.H. Whittaker (1969).
• It includes Monera, Protista, Fungi, Plantae & Animalia.
• This classification is based on cell structure, thallus organisation, mode of
nutrition, reproduction & phylogenetic relationships.

Organisms

Kingdom Kingdom Kingdom Kingdom Kingdom

Monera Protista Fungi Plantae Animalia

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 Characteristics of the five Kingdom
Characters Monera Protista Fungi Plantae Animalia
Cell type Prokaryotic Eukaryotic Eukaryotic Eukaryotic Eukaryotic
Non-cellulosic Present Present
Cell wall (polysaccharide + Present in some (Chitin & poly- (cellulose) Absent
amino acid) saccharides)
Nuclear
Absent Present Present Present Present
membrane
Body
Cellular Cellular Multicellular, Tissue/organ Tissue/organ/
organization loose tissue organ system

Autotrophic
(photosynthetic &
chemosynthetic) Autotrophic Heterotrophic Autotrophic Heterotrophic
Mode of
and heterotrophic (photosynthetic) (saprophytic (photo- (holozoic,
nutrition & heterotrophic or parasitic) synthetic) saprophytic etc)
(saprophyte/
parasite)

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KINGDOM MONERA
(BACTERIA)
 1. KINGDOM MONERA (BACTERIA)

• Bacteria are the most abundant microorganisms.

• Hundreds of bacteria are present in a handful of soil.
• They also live in extreme habitats such as hot springs,
deserts, snow & deep oceans.
• Many are parasites.

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 1. KINGDOM MONERA (BACTERIA)

Based on the shape, bacteria are 4 types:

Coccus (Spherical)

Bacillus (Rod-shaped)

Vibrium (Comma-shaped)

Spirillum (Spiral)

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1. KINGDOM MONERA (BACTERIA)

• Bacterial structure is very simple

but they are complex in
behaviour and show metabolic
diversity.
• Some bacteria are autotrophic
(synthesize food from inorganic
substrates).
• Majority are heterotrophs (they
do not synthesize the food but
depend on other organisms or on
dead organic matter for food).

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1. KINGDOM MONERA (BACTERIA) CLASSIFICATION

Halophiles

Thermo-
Archaebacteria acidophiles

Methanogens

Bacteria Photosynthetic
autotrophs
Autotrophs
Chemosynthetic
autotrophs
Eubacteria
Parasitic
Heterotrophs
Saprophytic

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1. KINGDOM MONERA (BACTERIA) 1. ARCHAEBACTERIA
• They live in harshest habitats such as extreme salty areas (halophiles), hot springs
(thermoacidophiles) and marshy areas (methanogens).
• Archaebacteria have a different cell wall structure for their survival in extreme
conditions.
• Methanogens are present in the guts of ruminant animals (cows, buffaloes etc). They
produce methane (biogas) from the dung of these animals.

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1. KINGDOM MONERA (BACTERIA) 2. EUBACTERIA

• They are True Bacteria having a rigid cell wall and a flagellum (if motile).
• They include Autotrophs (photosynthetic & chemosynthetic) and Heterotrophs.

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1. KINGDOM MONERA (BACTERIA) 2. EUBACTERIA
A. Photosynthetic autotrophs (E.g. Cyanobacteria)
• They have chlorophyll a similar to that of
green plants.
Cyanobacteria (blue-green algae)
• Unicellular, colonial or filamentous, marine
or terrestrial algae.
• The colonies are generally surrounded by
gelatinous sheath.
• They often form blooms in polluted water
bodies.
• Some of them fix atmospheric N2 in
specialized cells called heterocysts.
• E.g. Nostoc & Anabaena. AnabaenaNostoc
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1. KINGDOM MONERA (BACTERIA) 2. EUBACTERIA
B. Chemosynthetic autotrophs

Green sulphur bacteria Purple sulphur bacteria

• They oxidize inorganic substances such as

nitrates, nitrites & ammonia and use the
released energy for ATP production.
• They help in recycling nutrients like nitrogen,
Venenivibrio stagnispumantis
phosphorous, iron & sulphur.
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1. KINGDOM MONERA (BACTERIA) 2. EUBACTERIA
C. Heterotrophic bacteria

• They are the most

Hetero- abundant in nature.
trophic
• The majority are important
bacteria
decomposers.

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1. KINGDOM MONERA (BACTERIA) 2. EUBACTERIA
C. Heterotrophic bacteria: Impacts on Human affairs
Rhizobium

 They are used to make curd

from milk.
 Production of antibiotics.
 Fixing nitrogen in legume
roots etc.
Vibrio cholerae
 Some are pathogens
causing diseases.
E.g. Cholera, typhoid,
tetanus, and citrus canker.
Salmonella typhi

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1. KINGDOM MONERA (BACTERIA) REPRODUCTION

• Bacteria reproduce mainly by fission.

• Under unfavourable conditions, they produce spores.
• They also reproduce by a sort of sexual reproduction (DNA transfer from
one bacterium to other).

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1. KINGDOM MONERA (BACTERIA) MYCOPLASMAS

• They are organisms without a cell wall.

• They are the smallest living cells known.
• They can survive without oxygen.
• Many are pathogenic in animals and plants.
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PART 2

KINGDOM PROTISTA
 2. KINGDOM PROTISTA

It includes Well defined Some have

nucleus & other
single-celled membrane-bound
flagella or
eukaryotes. organelles. cilia.
 2. KINGDOM PROTISTA

Reproduce
Protists are It is a link with asexually and
primarily plants, animals sexually (cell
aquatic. and fungi. fusion & zygote
formation).
2. KINGDOM PROTISTA CLASSIFICATION

Protista

Chrysophytes

Dinoflagellates

Euglenoids

Slime moulds

Protozoans
 2. KINGDOM PROTISTA I. CHRYSOPHYTES
• Found in fresh water and marine environments.
• Microscopic and float passively in water currents (plankton).
• Most of them are photosynthetic.
• It includes diatoms & golden algae (desmids).
2. KINGDOM PROTISTA I. CHRYSOPHYTES
DIATOMS
• They have siliceous cell walls forming two thin overlapping shells, which fit together as in
a soap box.
• Diatoms are the chief ‘producers’ in the oceans.
2. KINGDOM PROTISTA I. CHRYSOPHYTES
DIATOMS
• They have siliceous cell walls forming two thin overlapping shells, which fit together as in
a soap box.
• Diatoms are the chief ‘producers’ in the oceans.
• The cell wall deposit of diatoms over billions of years in their habitat is known as
‘diatomaceous earth’. This is used in polishing, filtration of oils and syrups.
2. KINGDOM PROTISTA II. DINOFLAGELLATES
• Mostly marine and photosynthetic.
• They appear yellow, green, brown, blue or red depending on the main pigments in cells.
• Cell wall has stiff cellulose plates on the outer surface.
2. KINGDOM PROTISTA II. DINOFLAGELLATES
• Most of them have 2 flagella; one lies longitudinally and the other transversely in a
furrow between wall plates.
• Red dinoflagellates (E.g. Gonyaulax) undergo rapid multiplication so that the sea appears
red (red tides). They release toxins that kill marine animals like fishes.

Red tides
2. KINGDOM PROTISTA III. EUGLENOIDS
• Mainly fresh water organisms found in stagnant water.
• Instead of cell wall, they have a protein rich layer called pellicle. It gives flexibility to body.
• They have 2 flagella, a short and a long one.
2. KINGDOM PROTISTA III. EUGLENOIDS
• They are photosynthetic in the presence of sunlight.
• In the absence of sunlight, they behave like heterotrophs by predating on other organisms.
• The pigments are identical to those of higher plants.
• E.g. Euglena.
2. KINGDOM PROTISTA IV. SLIME MOULDS
• They are saprophytic protists.
• The body moves along decaying twigs and leaves engulfing organic material.
• Under suitable conditions, they form an aggregation called plasmodium. It
may spread over several feet.
2. KINGDOM PROTISTA IV. SLIME MOULDS
• Under unfavourable conditions, plasmodium differentiates and forms fruiting bodies
bearing spores at their tips.
• Spores have true walls. They are highly resistant and survive for many years.
• Spores are dispersed by air currents.
 2. KINGDOM PROTISTA V. PROTOZOANS
• They are heterotrophs (predators or parasites).
• They are primitive relatives of animals.

4 groups of Protozoans

Amoeboid Protozoans

Flagellated Protozoans

Ciliated Protozoans

Sporozoans
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2. KINGDOM PROTISTA V. PROTOZOANS
A. AMOEBOID PROTOZOANS
• Live in fresh water, sea water or moist soil.
• They move and capture prey by putting out pseudopodia (false feet). E.g. Amoeba.
• Marine forms have silica shells on their surface.
• Some are parasites. E.g. Entamoeba.

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 2. KINGDOM PROTISTA V. PROTOZOANS
B. FLAGELLATED PROTOZOANS
• Free-living or parasitic.
• They have flagella.
• Parasitic forms cause diseases like sleeping sickness. E.g. Trypanosoma.

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2. KINGDOM PROTISTA V. PROTOZOANS
C. CILIATED PROTOZOANS
• Aquatic, actively move using cilia.
• They have a cavity (gullet) that opens to outside.
• Due to the movement of cilia, water with food enters into gullet.
• E.g. Paramecium.

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2. KINGDOM PROTISTA V. PROTOZOANS
D. SPOROZOANS
• They have an infectious spore-like stage in their life cycle.
• E.g. Plasmodium (malarial parasite). It causes malaria.

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PART 3

KINGDOM FUNGI
 KINGDOM FUNGI
• Unique kingdom of heterotrophic organisms.
• They are cosmopolitan.
• They grow in warm and humid places.
• E.g. Bread Mould, Orange Rots, Mushroom, Toadstools etc.
• White spots on mustard leaves are due to a parasitic fungus.

Bread Mould Orange rots Mushroom Toadstool (Toxic

mushroom)
 KINGDOM FUNGI
• Some fungi are the source of antibiotics. E.g. Penicillium.
• Some unicellular fungi (e.g. Yeast) are used to make bread and beer.
• Other fungi cause diseases in plants and animals. E.g. wheat rust-causing Puccinia.
 KINGDOM FUNGI
• Except yeasts, fungi are filamentous. Their bodies consist
of long, slender thread-like structures called hyphae.
• The network of hyphae is known as mycelium.
• Hyphae are 2 types:
o Coenocytic hyphae: They are continuous tubes filled
with multinucleated cytoplasm.
o Septate hyphae: They have septae or cross walls.
• Fungal cell wall is made of chitin & polysaccharides.

Fungal cell wall

Septate hyphae Coenocytic hyphae
 KINGDOM FUNGI
• Most fungi are saprophytes (absorb soluble organic matter from dead substrates).
• Some are parasites.
• Some live as symbionts. E.g. Lichens (fungi+ algae), mycorrhiza (fungi + roots of higher
plants).

Liche Mycorrhiz
n a
KINGDOM FUNGI REPRODUCTION
Fragmentation
Vegetative
Fission
propagation
budding

Conidia
Asexual reproduction
Reproduction (By asexual spores)
Sporangiospores
Zoospores

Oospores
Sexual reproduction
Ascospores
(By sexual spores)
Basidiospores
KINGDOM FUNGI REPRODUCTION
1. Vegetative Propagation
By fragmentation, fission & budding.
KINGDOM FUNGI REPRODUCTION
2. Asexual Reproduction
By spores such as Conidia, Sporangiospores & Zoospores.
KINGDOM FUNGI REPRODUCTION
3. Sexual Reproduction
• By oospores, ascospores & basidiospores.
• They are produced in distinct structures called fruiting bodies.
KINGDOM FUNGI REPRODUCTION
3. Sexual Reproduction
• Plasmogamy: Fusion of protoplasm of two motile or non-motile gametes.
3 steps of
• Karyogamy: Fusion of two nuclei.
sexual cycle
• Meiosis in zygote resulting in haploid spores.
KINGDOM FUNGI REPRODUCTION
3. Sexual Reproduction
• In sexual reproduction, two haploid hyphae come together and fuse.
• In some fungi, fusion of 2 haploid cells immediately results in diploid cells (2n).
KINGDOM FUNGI REPRODUCTION
3. Sexual Reproduction
• In ascomycetes & basidiomycetes, a dikaryotic stage or dikaryophase (n + n i.e. two
nuclei per cell) occurs. Such a condition is called a dikaryon.
• Later, parental nuclei fuse and the cells become diploid.
KINGDOM FUNGI REPRODUCTION
3. Sexual Reproduction
• Fungi form fruiting bodies in which reduction division occurs, leading to formation of
haploid spores.
KINGDOM FUNGI CLASSIFICATION
Based on the morphology of mycelium, mode of spore formation and fruiting
bodies, Fungi are classified as follows:

4 classes of Fungi

Phycomycetes

Ascomycetes

Basidiomycetes

Deuteromycetes
KINGDOM FUNGI
I. PHYCOMYCETES (Lower Fungi)
• They occur in aquatic habitats and on decaying wood in moist and damp places or as
obligate parasites on plants.
• The mycelium is aseptate & coenocytic.
• E.g. Mucor, Rhizopus (bread mould) and Albugo (parasitic fungi on mustard).
KINGDOM FUNGI
I. PHYCOMYCETES (Lower Fungi)
Asexual reproduction Sexual reproduction

• By motile zoospores or non-motile • Fusion of two gametes form Zygospores.

aplanospores. • Gametes are isogamous (similar) or
• These are produced in sporangium. anisogamous or oogamous (dissimilar).
 KINGDOM FUNGI
II. ASCOMYCETES (Sac-Fungi)

• Unicellular (e.g. yeast, Sacharomyces) or multicellular (e.g.

Penicillium).
• Mycelium is branched and septate.
• They are saprophytic, decomposers, parasitic or coprophilous
(growing on dung).
KINGDOM FUNGI
II. ASCOMYCETES (Sac-Fungi)
• By conidia produced exogenously on the special mycelium called
Asexual conidiophores.
reproduction
• Conidia germinate to produce mycelium.
KINGDOM FUNGI
II. ASCOMYCETES (Sac-Fungi)

Sexual • By ascospores produced endogenously in sac like asci (sing. ascus).

reproduction • Asci are arranged to form ascocarps (fruiting bodies).
KINGDOM FUNGI
II. ASCOMYCETES (Sac-Fungi)
• Aspergillus, Claviceps & Neurospora.
Examples • Neurospora is used in biochemical and genetic work.
• Morels & truffles are edible and are delicacies.
KINGDOM FUNGI III. BASIDIOMYCETES

• Includes mushrooms, bracket fungi or puffballs.

• They grow in soil, on logs and tree stumps and in living plant
bodies as parasites (e.g. rusts & smuts).
• Mycelium is branched & septate.

Mushrooms Bracket fungi Puffballs

KINGDOM FUNGI III. BASIDIOMYCETES
• The asexual spores are generally not found, but vegetative reproduction by
fragmentation is common.
• Sex organs are absent, but plasmogamy occurs by fusion of two vegetative or somatic
cells of different strains or genotypes. The resultant structure is dikaryotic. It gives rise
to basidium.
KINGDOM FUNGI III. BASIDIOMYCETES
• Karyogamy & meiosis occur in basidium producing 4 basidiospores
exogenously.
• Basidia are arranged in fruiting bodies called basidiocarps.
• E.g. Agaricus (mushroom), Ustilago (smut) & Puccinia (rust fungus).
KINGDOM FUNGI IV. DEUTEROMYCETES

• Commonly known as imperfect fungi because only

their asexual or vegetative phases are known.
• When perfect (sexual) stages were discovered they
were often moved to ascomycetes or
basidiomycetes.
• It is also possible that the asexual and vegetative
stage have been given one name placing under
deuteromycetes and the sexual stage another
name placing under another class. When the
linkages were established, the fungi were correctly
identified and moved out of deuteromycetes.
KINGDOM FUNGI IV. DEUTEROMYCETES
• Deuteromycetes reproduce only by asexual spores (conidia).
• Mycelium is septate and branched.
• Some are saprophytes or parasites. Majority are
decomposers of litter and help in mineral cycling.
• E.g. Alternaria, Colletotrichum and Trichoderma.
KINGDOM PLANTAE
KINGDOM PLANTAE
 KINGDOM PLANTAE (PLANT KINGDOM)
• Plants are eukaryotic chlorophyll-containing organisms with cellulosic cell wall.
• Some are partial heterotrophs such as the insectivorous plants (e.g. Bladderwort and
Venus fly trap) or parasites (e.g. Cuscuta).

bladderwort Cuscuta
KINGDOM PLANTAE (PLANT KINGDOM)

Plantae includes
 Algae
 Bryophytes
 Pteridophytes
 Gymnosperms
 Angiosperms
 KINGDOM PLANTAE (PLANT KINGDOM)

Life cycle of plants has two phases: diploid sporophytic & haploid gametophytic. These
phases alternate with each other. This phenomenon is called alternation of generation.
KINGDOM ANIMALIA
 KINGDOM ANIMALIA (ANIMAL KINGDOM)

• Animals are multicellular,

heterotrophic, eukaryotic organisms
without cell wall.
 KINGDOM ANIMALIA (ANIMAL KINGDOM)

• They directly or indirectly depend on plants for

food.
• They digest their food in an internal cavity and
store food reserves as glycogen or fat.
• Their mode of nutrition is holozoic (by ingestion
of food).
 KINGDOM ANIMALIA (ANIMAL KINGDOM)

• They have a definite growth

pattern and grow into adults that
have a definite shape and size.

• Higher forms show sensory and

neuromotor mechanism.
 KINGDOM ANIMALIA (ANIMAL KINGDOM)

• Most of them are capable of locomotion.

• The sexual reproduction is by copulation of

male and female followed by embryological
development.
VIRUSES, VIROIDS,
PRIONS, LICHENS
 VIRUSES, VIROIDS, PRIONS AND LICHENS
• They are not mentioned in five-
kingdom classification.
• Viruses, viroids & prions are non-
cellular and not truly living. So they
are not included in the classification.

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• Viruses have an inert crystalline structure outside the living cell.
• Viruses are obligate parasites.
VIRUSES • When they infect a cell they take over the machinery of host cell to
replicate themselves, killing the host.

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 VIRUSES, VIROIDS, PRIONS AND LICHENS

• Louis Pasteur: Gave the name virus (means venom or

VIRUSES poisonous fluid).

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• D.J. Ivanowsky (1892): Discovered virus.
• He recognized certain microbes that cause mosaic disease
VIRUSES of tobacco. They were smaller than bacteria because they
passed through bacteria-proof filters.

Tobacco mosaic virus

Mosaic disease of tobacco

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• M.W. Beijerinck (1898): Demonstrated that the extract of
the infected plants of tobacco could cause infection in
VIRUSES healthy plants and called the fluid as Contagium vivum
fluidum (infectious living fluid).

Tobacco mosaic virus

Mosaic disease of tobacco

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 VIRUSES, VIROIDS, PRIONS AND LICHENS

• W.M. Stanley (1935): Showed that viruses could be

VIRUSES crystallized and crystals consist largely of proteins.

Bovine Enterovirus 2 Satellite Tobacco Mosaic Virus crystals

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• A virus is a nucleoprotein, i.e., it has a protein coat (capsid) & genetic
material (RNA or DNA).
VIRUSES • No virus contains both RNA & DNA.
• The genetic material is infectious.

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• Generally, viruses that infect plants have single stranded RNA.
• Viruses that infect animals have either single or double stranded RNA or
VIRUSES double stranded DNA.
• Bacteriophages (viruses that infect bacteria) usually have double stranded DNA.

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 VIRUSES, VIROIDS, PRIONS AND LICHENS

• The protein coat (capsid) made of small subunits (capsomeres) protects

VIRUSES nucleic acid.
• Capsomeres are arranged in helical or polyhedral geometric forms.

Helical Polyhedral geometric

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 VIRUSES, VIROIDS, PRIONS AND LICHENS

• Viruses cause diseases like mumps, small pox, herpes, influenza & AIDS.
VIRUSES • In plants, the symptoms can be mosaic formation, leaf rolling & curling,
yellowing & vein clearing, dwarfing & stunted growth.

Mumps Small pox Herpes Influenza AIDS

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VIRUSES, VIROIDS, PRIONS AND LICHENS
 VIRUSES, VIROIDS, PRIONS AND LICHENS
• It is an infectious agent with a free low molecular weight
RNA and no protein coat.
VIROIDS • These are smaller than viruses.
• It is discovered by T.O. Diener (1971).
• He found that it caused potato spindle tuber disease.

Viroid Potato spindle tuber

disease

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• These are abnormally folded protein that cause some infectious neurological
diseases.
PRIONS • These are similar in size to viruses.
• They cause bovine spongiform encephalopathy (BSE) or mad cow disease in
cattle and its analogous variant Cr-Jacob disease (CJD) in humans.

Mad cow disease Creutzfeldt-Jakob disease

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• They are symbiotic associations (mutually useful associations) between
algae & fungi.
LICHENS • The algal component is called phycobiont (autotrophic) and fungal
component is mycobiont (heterotrophic).

Foliose tree-dwelling lichen

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 VIRUSES, VIROIDS, PRIONS AND LICHENS
• Algae prepare food for fungi and fungi provide shelter and absorb mineral
nutrients and water for its partner.
LICHENS • Lichens are very good Pollution indicators. They do not grow in polluted
areas.

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