Classification of Organisms: A Comprehensive Guide
Proposed by Linnaeus
➢ Kingdom Plantae and kingdom Animalia
➢ DEMERITS :-
1. Did not distinguish between the eukaryotes
and prokaryotes.
2. Did not distinguish between unicellular and
multicellular organisms
3. Did not distinguish between photosynthetic
and non-photosynthetic organisms.
➢ Proposed by R.H.
Whittaker (1969)
➢ It includes Monera, Protista, Fungi, Plantae and
Animalia
➢ Criteria for classification are,
1. Cell structure,
2. Body organization
3. Mode of nutrition
4. Reproduction
5. Phylogenetic relationships
KINGDOM MONERA
Prokaryotic, heterotrophic, unicellular organisms with non-cellulosic cell wall.
It includes bacteria.
Classification of Bacteria
Based on shape Types of Archaebacteria
Coccus Spherical Halophiles Lives in extreme salty
area
Bacillus rod-shaped Thermoacidophiles Lives in hot springs
Vibrium comma-shaped Methanogens Lives in marshy areas
Spirillum spiral
Methanogens are present in the gut of cows and
buffaloes and they are responsible for the
production of biogas (methane).
Cyanobacteria or blue-green algae
Eg :- Nostoc and Anabaena
They are eubacteria having chlorophyll a similar to green plants and are photosynthetic autotrophs.
Specialised cells called heterocysts in cyanobacteria can fix atmospheric nitrogen.
Chemosynthetic autotrophic bacteria – Oxidise various inorganic substances such as nitrates, nitrites
and ammonia for energy (ATP) production. Mycoplasma – Organisms that completely lack a cell wall. They are the smallest living cells.
KINGDOM PROTISTA
Single-celled eukaryotes showing autotrophic (Photosynthetic) and heterotrophic mode of nutrition.
It includes Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans.
Chrysophytes :- It includes diatoms and golden algae (desmids). Diatomaceous earth :-
The accumulation of cell wall deposits of diatoms over billions of years in sea-floor.
Diatomaceous earth is used in polishing, filtration of oils and syrups.
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 4
Dinoflagellates
Marine and photosynthetic unicellular organism that appear yellow, green, brown, blue or red
depending on the main pigments present in their cells. Gonyaulax –
Red tides causing dinoflagellates that make the sea appear red.
Toxins released by such dinoflagellates kill marine animals such as fishes.
Euglenoids Example: Euglena
They are photosynthetic in the presence of sunlight, when deprived of sunlight they are
heterotrophs.
Pellicle – Protein rich layer around the cells of euglenoids.
Slime Moulds
They are saprophytic protists
Under suitable conditions, they form an aggregation called plasmodium.
Protozoans – Protozoans are heterotrophs and live as predators or parasites.
MAJOR GROUPS OF PROTOZOANS ARE
Types of Protozoans characteristics Examples
Amoeboid protozoans
Pseudopodia (false feet) are produced for
capturing prey. Amoeba, Entamoeba
Flagellated protozoans They have flagella. Trypanosoma
(Causes sleeping sickness diseases)
Ciliated protozoans Actively moving organisms due to the
presence of thousands of cilia. Paramoecium
Sporozoans They have an infectious spore-like stage. Plasmodium (malarial parasite)
which causes malaria
KINGDOM FUNGI
Fungi consist of heterotrophic organisms with cell walls composed of chitin and polysaccharides.
Hyphae – Fungal bodies consist of long, slender thread-like structures called hyphae.
Mycelium – The network of hyphae is known as mycelium. Coenocytic hyphae – hyphae with multinucleated cytoplasm are called coenocytic hyphae.
Lichens – Symbiotic association of fungi with algae. Lichens are pollution indicators.
Algal component is known as phycobiont and fungal component as mycobiont.
Mycorrhiza – symbiotic association of fungi with roots of higher plants.
Unicellular fungi – Yeast
Wheat rust-causing fungi – Puccinia
Antibiotics producing fungi – Penicillium
The sexual cycle in fungi have following three steps:
• Fusion of protoplasm between two motile or non-motile gametes called plasmogamy.
• Fusion of two nuclei called karyogamy.
• Meiosis in zygote resulting in haploid spores.
Dikaryon – In fungi (ascomycetes and basidiomycetes)
Fusion of two nuclei is delayed.
Single hyphal cell contains two nuclei.
Such a condition is called a dikaryon and the phase is called dikaryophase.
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 5
MAJOR GROUPS OF FUNGI ARE
Types of Fungi Characteristics Examples
Phycomycetes
•Mycelium is aseptate and coenocytic.
•Asexual reproduction takes place by zoospores
(motile) or by aplanospores (non-motile).
•During sexual reproduction zygospore is formed by
fusion of two gamete.
Rhizopus (the bread mould)
Albugo (parasitic fungi on
mustard).
Ascomycetes
(Sac-fungi)
•Asexual spores are conidia produced exogenously on
the conidiophores.
• Sexual spores are called ascospores which are
produced endogenously in sac like asci. So called sac
fungi.
• fruiting bodies are called ascocarps.
Aspergillus
Claviceps
Neurospora.
Basidiomycetes
•Basidiospores are the sexual reproductive Spores.
• The basidiospores are exogenously produced on the
basidium.
• The basidia are arranged in fruiting bodies called
basidiocarps.
Agaricus (mushroom)
Ustilago (smut fungus)
Puccinia (rust fungus)
Deuteromycetes
(Imperfect fungi)
• Known as imperfect fungi because only the asexual
phases of these fungi are known.
• They reproduce only by asexual spores known as
conidia.
Alternaria
Colletotrichum
Trichoderma
VIRUSES
A virus is a nucleoprotein and the genetic material is infectious.
Bacteriophages (viruses that infect the bacteria) are usually double stranded DNA viruses.
The protein coat of virus is called capsid and is made of small subunits called capsomeres.
Dmitri Ivanowsky – gave the name virus that means venom or poisonous fluid.
M.W. Beijerinek – Explained virus as Contagium vivum fluidum (infectious living fluid).
W.M. Stanley – Crystallised the viruses and crystals consist largely of proteins.
Examples for virus diseases: – Mumps, small pox, herpes and influenza. AIDS in humans.
Mosaic formation, leaf rolling and curling, yellowing and vein clearing in plants.
VIROIDS Discovered by T.O. Diener.
Smaller than viruses and causes potato spindle tuber disease.
It was found to be a free RNA, it lacked the protein coat.
Prions
Abnormally folded diseases causing protein.
Diseases caused by prions are,
Bovine spongiform encephalopathy (BSE) commonly called mad cow disease in cattle
Cr–Jacob disease (CJD) in humans.
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 6
Chapter 3
PLANT KINGDOM
Artificial classification – based only on gross superficial morphological characters.
Eg. :- Linnaeus classification.
Natural classification – based on natural affinities among the organisms.
Eg. :- Bentham and Hooker classification.
Phylogenetic classification – based on evolutionary relationships between the various organisms.
Numerical Taxonomy – based on all observable characteristics. Number and codes are assigned to all
the characters.
Cytotaxonomy – based on cytological information like chromosome number, structure and behaviour.
Chemotaxonomy – based on the chemical constituents.
ALGAE
Chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic organisms.
Asexual reproduction is by the production of zoospores.
colonial forms like Volvox and the filamentous forms like Ulothrix and Spirogyra.
Sexual reproduction may be,
Isogamous: – gametes are flagellated / non-flagellated and similar in size. Eg :- Ulothrix
Anisogamous: – gametes dissimilar in size. Eg :- Eudorina.
Oogamous: – Fusion between one large, nonmotile female gamete and a smaller, motile male gamete.
e.G. :- Volvox, Fucus.
Economic importance of algae
1. Algae fix at least a half of the carbon dioxide fixation on earth
2. They are the primary producers
3. Algae produce large amounts of hydrocolloids
e.G.:- algin (brown algae) and carrageen (red algae).
4. Agar produced by the red algae such as Gelidium and Gracilaria is used in the preparations
of ice-creams and jellies.
5. Chlorella is used as food supplement
Classification of Algae
Classes
(Common Name) Major Pigments Stored Food Cell Wall Examples
Chlorophyceae
(Green algae) Chlorophyll a, b Starch Cellulose
Chlamydomonas,
Volvox, Ulothrix,
Spirogyra and Chara
Phaeophyceae
(Brown algae)
Chlorophyll a, c
fucoxanthin
Mannitol
Laminarin
Cellulose and
algin
Ectocarpus,
Dictyota, Laminaria,
Sargassum and
Fucus
Rhodophyceae
(Red algae)
Chlorophyll a, d
phycoerythrin Floridean starch Cellulose and
pectin
Polysiphonia,
Porphyra, Gracilaria
and Gelidium
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 7
BRYOPHYTES
Bryophytes are also called amphibians of the plant kingdom because they live in soil but are
dependent on water for sexual reproduction.
The bryophytes are divided into liverworts and mosses.
The male sex organ is called antheridium producing male gamete called antherozoids.
The female sex organ called archegonium.
Economic importance of Bryophytes
Sphagnum (moss) provide peat that have long been used as fuel.
Sphagnum is used as packing material of living material because of their capacity to hold water.
Liverworts e.G., Marchantia
Gemmae
Gemmae are green, multicellular, asexual buds, which develop in small receptacles called gemma cups
Mosses e.G. :- Funaria, Polytrichum and Sphagnum
Protonema stage :-
Creeping, green, branched and filamentous gametophytic stage develops directly from a spore.
Leafy stage,
It develops from the protonema as a lateral bud and consist of upright, slender axes bearing spirally
arranged leaves.
sporophytic stage
After fertilisation, the zygote develops into a sporophyte.
The sporophytic stage consist of a foot, seta and capsule.
PTERIDOPHYTES
It includes horsetails and ferns.
They are the first terrestrial plants to possess vascular tissues – xylem and phloem.
Sporophytic plant body bear sporangia that are developed on leaf-like appendages called sporophylls.
In Selaginella, Equisetum sporophylls aggregate to form compact structures called strobili or cones.
Prothallus – free-living, green, mostly photosynthetic thalloid gametophytes developed from spores.
Homosporous Heterosporous
similar types of spores are produced.
Eg :- Lycopodium, Equisetum
Two kinds of spores are produced.
Large macrospores and small micro spores. Heterospory is a precursor to the seed habit
Eg :- Selaginella and Salvinia
Seed Habit
In pteridophytes the female gametophytes are retained on the parent sporophytes.
The zygotes formed within the female gametophyte develop into embryos. GYMNOSPERMS
Eg :- Cycas, Pinus, Sequoia (tallest tree), Ginkgo
Gymnosperms are naked seeded (seeds are not covered) plants.
Naked seeded – Gymnosperms produce seed without fruit /Ovary is absent so ovules are not enclosed.
Coralloid roots – Specialised roots of Cycas which are associated with N2 – fixing cyanobacteria.
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 8
Chapter 5
MORPHOLOGY OF FLOWERING PLANTS
Tap root system
The primary roots with its lateral roots in dicot are called tap root system.
Fibrous root system
The roots developed from the base of the stem in monocots are called fibrous root system.
Adventitious roots
Roots that are developed from the part other than radicle is called adventitious roots.
Eg :- Monstera
Regions of Root
✓ The root has the following four parts,
1. Root Cap
2. Region of Meristematic activity
✓ The cells in this regions are actively dividing.
3. Region of Elongation
4. Region of Maturation
✓ Root hairs are developed from this region.
VENATION
✓ The arrangement of veins and veinlet in the leaf lamina is called venation.
✓ There are two types of venation,
1. Reticulate Venation – Vein and veinlet form a network on leaf lamina
Characteristic in dicotyledonous plants.
2. Parallel Venation – Vein and veinlet run parallel to each other on leaf lamina
Characteristic in monocotyledonous plants.
TYPES OF LEAVES.
Simple Leaf – Leaf with single entire leaf lamina, if the lamina is incised it does not touch the midrib.
Compound Leaf – Leaf with a number of leaflets is called compound leaf.
It may be of two types,
Pinnately Compound Leaf
The leaflets are arranged on either side of common axis called rachis. Eg :- Neem.
Palmately Compound Leaf
The leaflets are attached at a common point. Eg :- Silk Cotton
Phyllotaxy :- The mode of arrangement of leaf on stem or branch. 3 Types
Alternate Opposite Whorled
Single leaf in each node Two leaves in each node arranged in
opposite manner
More than two leaves in each
node
Eg :- China Rose,
Mustard
Eg:- Calotropis & Guava Eg:- Alstonia
Inflorescence :- The arrangement of flowers on floral axis is called inflorescence.
Two types
Racemose :- Flowers in acropetal succession Cymose :- Flowers in basipetal order
Main axis continues to grow. Main axis terminates in a flower.
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 9
Types of Flowers
TYPES CHARACTER EXAMPLE
A)
Actinomorphic Can cut into two equal halves
through any radial plane
Mustard, Chilli
Zygomorphic Can cut into two equal halves
only through one vertical plane
Pea, Bean & Cassia
B)
Asymmetric Cannot be cut into two equal
halves
Canna
A) Hypogynous Ovary superior China rose, Mustard
C)
B) Perigynous Ovary half inferior Rose, Peach
C) Epigynous Ovary inferior Cucumber,
sunflower
Aestivation :- The mode of arrangement of sepals or petals in a flower
Valvate Twisted Imbricate Vexillary/Papilionaceous
Overlapping absent Regular overlapping Overlapping present,
one in and one out
5 petals – 1 large standard
petal, 2 lateral wing petals
and 2 united keel petals
Eg:- Calotropis Eg:- China rose & cotton Eg:- Cassia & Gulmohur Eg:- Pea & bean
Placentation :- Arrangement of ovules within the ovary
Marginal Axile Parietal Free central Basal
Ovule present on
the margin of ovary
Ovule present on the
central axis of ovary
Ovule present on the
inner wall of ovary
Ovule present on the
central axis without
septa of ovary
Ovule present in
the base of ovary
Eg:-Pea Eg:-China rose,
Lemon
Eg:- Mustard Eg:-Dianthus Eg:-Sunflower
Floral Characters
Calyx – composed of sepals; gamosepalous – Sepals united; Polysepalous – Free sepals
Corolla – composed of petals; gamopetalous – Petals united; Polypetalous – Free petals
Perianth – composed of tepals.
Androecium – composed of Stamens, Epipetalous – Stamen attached to petals; Epiphyllous – stamens
attached to perianth;
Polyandrous – free stamens; Monoadelphous- Stamen united to form single bundle;
Diadelphous – Stamen united to form two bundles. Polyadelphous – Stamens in more than two bundle
Gynoecium – composed of carpels; Syncarpous – capels united; Apocarpous- Carpels free
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 10
Symbols Expansion Symbols Expansion
K Calyx Actinomorphic flower
C Corolla Zygomorphic flower
P Perianth K(5) Calyx consist of 5 sepals, gamosepalous
A Androecium C(5) Corolla consist of 5 petals,gamopetalous
G Gynoecium Bisexual flower
G
superior ovary, hypogynous
flower
Bicarpellary, syncarpous & superior
ovary
G Inferior ovary, epigynous flower Epipetalous stamens
G
Half Inferior ovary, perigynous
flower 5 stamens, free stamens
Parthenocarpic Fruit :- The fruit formation without fertilization. Drupe :- Fruit of coconut and mango.
Pericarp :- Fruit wall is called pericarp.
It is differentiated into outer epicarp, middle mesocarp and inner endocarp.
Aleurone layer :- Outer proteinous covering of monocot seed.
Scutellum :- Single large shield shaped cotyledon of monocot seed.
Coleoptile and Ccoleorhiza :- Plumule and radicle are enclosed in sheaths which are called coleoptile and
coleorhiza respectively.
SOLANACEAE
Flower: bisexual, actinomorphic
Calyx: sepals five, united, persistent, valvate aestivation
Corolla: petals five, united; valvate aestivation
Androecium: stamens five, epipetalous
Gynoecium: bicarpellary obligately placed, syncarpous; ovary superior, bilocular, placenta swollen
with many ovules, axile placentation.
Economic Importance: Source of food (tomato, brinjal, potato), spice (chilli)
medicine (belladonna, ashwagandha), fumigatory (tobacco), ornamentals (petunia).
Join Now: https://join.Hsslive.In Downloaded from www.Hsslive.In ®
DR. SUNIL KUMAR. S, GFVHSS CHERUVATHUR, PH : 9495824297 11