There are some characteristics of living beings used to
distinguish them from non-living things. These arc as
follows

(i.) Protoplasm It is the physical basis of life. All the metabolic activities occurs inside the protoplasm. It
is the most dynamic feature of a living being. Life is dependent upon this dynamic nature of protoplasm.

(ii) Cell Structure Living beings arc made up of one or more cells. A cell is the structural and functional
unit of life. It is the most peculiar feature of living orgamsms.

(iii) Nutrition Living beings require energy, that they can use for growth and development. They get this
energy from food. Nutrition is the process by which organisms obtain energy from nutriems such
as proteins, carbohydrates and fats. For examples, plants make food from water, minerals and `CO2` in
the presence of sunlight with the help of chlorophyll.
(iv) Metabolism It is the sum total of all the chemical reactions taking place in an organism. Metabolism
includes anabolism (making of substances) and catarolism (breaking of substances). Metabolism
leads to energy production in an organisms.

(v) Resjpiration It is an important characteristic of all living beings. In this process, they take up oxygen
and release carbon dioxide. By this process the energy stored in food, is released and it is utilised
for various activities.

(vi) Movement All living things show movement. Animals show locomotion to search for food,
shelter, mate, etc. Plants show movement of their parts or organs in response to a stimuli such as
sunlight. In non-living organisms mechanical movement may be present.

(vii) Growth The increase in the shape, size and dry weight of living beings is called growth. Plants may
grow indefinitely with the help of meristematic tissue. But in animals growth is definite and it stops
at a certain age.

(viii) Reproduction All living being can produce offspring in a process called reproduction.

(ix) Sensitivity and Adaptibility All living beings can sense all the changes occuring around them. Thus,
they are sensitive to different conditions and can also adapt to these conditions.

(x) Excretion In living beings, as a result of many chemical reactions, certain toxic substances arc
produced. Living beings can remove these substance in the process of excretion. It is defined as the
remoral of toxic materials, from the body of an orgarusm.

(xi) Life Cycle All living organisms possess a definite life cycle, which is the cycle of birth, reproduction
and ultimately death.

'Life Sciences' refers to the broad study of living organisms. It involves other branches of science such as physics,
chemistry, mathematics also. This is necessary to study these branches in life sciences mainly because of following aspects

(i) All living organisms are made up of inorganic and organic molecules.

(ii) Inorganic compounds dissolve in water to form ions, which influence life activities.

(iii) The pH of living organisms is maintained by acid-base equilibrium.

(iv) The movement of molecules in and out of the cell is governed by diffusion and osmosis.

(v) Light plays an important role in inducing definite pattern of responses.

(vi) Living beings exchange their energy with surroundings hence, they are example of open system.

(vii) The science of mathematics and statistics help us in compiling and analysing biological data.

Classifying the living organisms into different categories aid to the study of various organisms.

'Taxonomy' (Gr. Tatxis-arrangement, nomos-law) is that branch of science, in which the means of identification and
classification arc studied.

• In the 18th century, a Swedish biologist Carolus Linnaeus developed a scheoe of scientific classification and devised a
system of scientific nomenclature. According to him, all organisms have some important characteristics in common
and different from others in one or more ways. Based on these characteristic:s, organisms are placed in different
categories. Linnaeus also proposed the binomial nomenclature in his book Species Plantarum.

• According to this, the scientific name of each organism is composed of two names, i.e. a generic name and a species
name. The generic name begins with a capital letter and species name begins with a small letter, i.e. zoological name
of the common housefly is Musca domestica and that of human is Homo sapiens. The botanical name of wheat is
Triticum aestivum.

• While classifying organisms, they are grouped into different categories. For example, potato
belongs to Solanum genus of family-Solanaceae, which comes under
Solamles order of division-Eudicots of kingdom--Plantae. Each such category is
known as a taxon, e.g. family, class, genus, etc. This hierarchial system or a series of
classification was introduced by Linnacus. The major categories of hierarchy arc given below

• The basis of this hierarchy categorisation is to separate organisms on the basis of
characteristics, i.e. from larger or higher to smaller and smaller groups to reach the basic
unit of classification, i.e. species.

• The history of classification started from Hippocratt!S (460-377 BC) and till now
different classification has been proposed. Some of them are as follows

Carolus Linnaeus ( 1758) placed all the living organisms in two major kingdoms, i.e. Plantae for
plants and Animalia for animals. This system is known as two kingdom system of classification.
In this categorisation, the position of some organisms like Euglena, blue-green algae, fungi,
etc., was debatable

Copeland (1956) divided the organisms into four kingdoms, i.e. Monera (bacteria and blue-green
algae), Protista (red and brown algae, fungi and Protozoa), Plantae and Animalia. It is known as
four kingdom system of classification. In it, the position of fungi in Protista was debatable.

RH Whittaker (1969) classified the organisms into five major kingdoms, i.e. Monera, Protista,
Fungi, Plantae and Animalia on the basis of cell structure, plant body organisation, nutrition mode,
reproduction and ancestral relationships. It is called five kingdom system of classification.
This was the first kingdom system classified the debatable organism in proper place. The major
differences in the characteristics of different kingdoms arc as follows

=> Kingdom-Moncra includes the small, simple, microscopic organisms that arc found everywhere. These arc mostly unicellular
and prokaryotic organisms, which do not have a true (well defined) nucleus and organelles, e.g. bacteria, mycoplasma.
Bacteria arc major/main organisms of this kingdom. They lack true nucleus and present in each and every habitat including some
extreme area like hot spring:;, snow and deep oceans. They are known as the scavengers of earth.

Bacteria are of two types

(i) Archacbactcria (ii) Etbactcria

• Bacteria can also be distincted on the basis of nutrition the bacteria may be autotrophic (self food producing) or heterotrophic (taking food from others).

• Similarly , on the basis of shape, they can be cocci (sphere-shaped), bacilli (rod-shaped), spirilli (spiral-shaped), vibrio (comma-shaped),
actinomycetes (branched). In 1884, Christian Gram proposed, a staining technique to distinguish bacteria. This technique is
known as Gram staining. Based on this, bacteria can be either Gram positive or Gram negative.

Kingdom-Protista includes all eukaryotic single-celled organisms.

They have well defined nucleus and other membrane bound organelles Members of this kingdom arc mostly marine. They
mostly possess cillia or flagella for moving. They can be either autotrophic or heterotrophic.

fungi is a group of unique organism that are heterotrophic eukaryotic. They possess a cell wall made
of chitin. These organisms derive their nutrition from dead-delaying substances. Hence, are saprotrophic

They lack chlorophyll. Body of a fungus is made up of Glaments (thread-like) called hyphae, which fonr. a
work called mycellium. Reproduction takes place by mentation (asexual) and sexual.

Fungi are usually found in mutualistic relationships a other organisms. For example, lichen is a
ambiotic organism having a fungal and and algal partner. The fungus provide shelter to the algae and
algae provides nutrition to fungi, e.g. Ptzrmcllia, Usnea, etc.


Mushroom
These are ased as food due to their flavour, protein and vitamin contents. Agaricus campesris is common edible
mushroom, whereas Amanita phyylloidos is poisonous in nature.

• Kingdom-Plantae includes all plants. These are cukaryotic, multicellular organisms. They possess a cell
wall made of cellulose. They are autotropbic, i.e. they can make their food in sunlitght with the help of
chlorophyll bra process called as photosynthesis.

• First level of classification among plants depends on whether the plant body possess well-differentiated
distinct components or not.

• Next level is based on the presence or absence of special vascular tissues for the transport of water and
other substances. Further classification takes into account the ability to bear seeds and whether seeds are
enclosed within fruits or not.

• Thallophyra, Bryophyta and Ptcriodophyta comes under Crypotogamae division of kingdom- Plantae.


• Crypwgamme are those organisms, which do not have visible sex organs and seeds, i.e. Thallophyta, Bryophyta
and Pteridophyta. On the other hand organisms with evident sex organs and seeds arc included in
Phancrogamae.

Organisms of this group do not have well differentiated body design, i.e. their body do not s.how differentiation
into root., item ,and leaves. This type of body is called thalloid body. They are commonly known ,is algae and
are predominantly aquatic. Their cell wall is made of cellulose. They follow autotrophic mode of nutrition and
their reserve food is generally starch. Algae arc mostly non-vascular, i.e. they do not have vascular tissue.

e.g. Ulothnx, Spirogyua, Chana, etc.

Algae are Usually of three types depending upon types of pigment present in them bron algae (xanthophyll), green
algae (chlnrophyk) and red algae (r-phycoerythrin).

Organism of this group are called as the amphibians of the plant kingdom because they can live in soil, but are
dependent on water for sexual reproduction.

In bryophytes , true vasculer system i.s ,absent, i.e. they do not have· spccialied tissue for the cunduction of water and
food materials from one part of the body to another .


The body is commonly differentiatd into stem and leaf-·like structures. They lack real roots, stems, leaves , etc, and do
not bear flower. lt includes liverworrts ( Riccia, Marchantia), mosses (Funaria, Sphagmon) and hornnworts (Anthoceros).

Sphagman is an economically important bryophyte used as a constitment of peat. It is also useful in transportation of
moisture requiring products.

These are first land plants having vascular tissues. The body of these plants is differentiated into mots, stems and
leaves and has specialised tissue for the conduction of water and food (well-developed vascular system, xylem and
phloem).


Thus, are called vascular cryptogams. They do not bear flowers and do not produce seeds.

These include ferns (Marsilea, Azolla, Adiantum, Dryoprcris, Pteris , and Pteridium ), club moss ( Selaginella ), horsetails
(Eqniseium).

These plants are most primitive and they bear seeds. The seeds produced are naked and are not enclosed within
fruits.

flower formation is also absent . These plants are usually perennial, evergreen and woody. Xylem lacks vessels and
phloem lacks , companion cells. Cycas, Pinus (pine), Cedrus (deodar) and Ginky, (living fossil ).

These plants are also called as flowering plants as they contain their sex organs inside flower.

Their seeds develop inside ovary (female reproductive part), which modifies to become a fruit. Plant embryos in seeds
have structures, called cotyledons. which are embryonic leaves.

The angiosperms are divided into two groups on the basis of number of cotyledons present in the seed. These
includes monocotyledons (1 cotyledon) or dicotyledons (2 cotylelons) .

This kingdom includes animals ranging from Protozoa to mammals.

• These organisms are eukaryotic and heterotrophic. Their cells do not have cell walls and chloroplast. Most
of the animals show locomotion and store glycogen ( animal-starch).

• Unicellular animal arc Protozoa, while multicellular animals arc Metazoa.

• Animals are classified depending upon the presence or absence notochord.

lnvertcbrates account for `95%`, of the total animal species.

In invertebntcs, notochord is absent. Non-chordata divided into two sub-kingdom.


1. Sub-kingdom-Protozoa


• Protozoans arc small, microscopic, unicellular organisms with varied forms.

• They may be aquatic (freshwater or marine), terrestrial, free-living or parasites, parasitic forms cause diseases in
humans and animals. The mode of nutrition can be holozoic, holophytic or parasitic.

• They show intracellular labour division, i.e. different
organelles arc present to perform different functions.

• Locomotory organelles arc pseudopodia!, flagella or cilia. Exchange of gases takes place through ~he general
body surf ace of the individuals.

• Excretion occurs by contractile vacuole through general body surface. Asexual reproduction occurs by binary
fission (e.g. Leishmania), multiple fission or budding (e.g. Plasmodium). Sexual reproduction occurs by
syngamy or conjugation.


Classificatiion

On the basis of locomotory organs, phylum-Protozoa is
divided into four groups

(i) Zooflagcllata, e.g. Trypanosoma , Leishmania, Giardia.

(ii) Sarcodina (Rhizopoda), e.g. Amoeba, Entamoeba.

(iii) Sporozoa, e.g. Plasmodium.

(iv) Ci.iiata, e.g. Vorticella, Optdina.


2. Sub-kiingdom-Metazoa


Sub-kingdon-Jvlctazoa includes following phyla

Phylum-Porifera (Sponges)

• AII sponges arc aquatic, mostly marine, rarely freshwater (e.g. Spongillia ), solitary or colonial.

• They have cellular or tissue level organisation .They are diploblastic.

• Sponges have high generative power.

• Body is porous. The pores arc of two types, i.e. ostia and osculun.

• The central body cavity of a sponge is called spongocoel.

• For protection they possess cells called as cnidoblasts.

• Spongococl is lined by flagellate cells called collar cells.
Skeleton forming cells arc called sclcrocytes.

• Skeleton is made up of either siliceous spicules or
proteinaceous spongin fibres or both.

• Sponges reproduce both asexually (by budding) and
sexually. Sponges have very high regeneration power.

Classification

On the basis of skeleton, phylum-Porifera is divided into
three classes

(i) Calcarea, e.g. Sycon, Leucosolenia.

(ii) HexaKtincllida or Hyalospongiac, e.g. Euplectella, llyrdoncma.

(iii) Dcmospongiac, e.g. Fuspongia, Spongilla

• Some common sponges arc

(i) Euplcctella (venus flower basket)

(ii) Hytdonema (glass rope sponge)

(iii) Euspongla (bath sponge)

(v) Chalina (mermaid's glove)

(v) Hiippospongw (horse sponge)

• All arc aquatic, mostly marine except a few like Hydra.

• Coelenterates possess cell-tissue level of organisation.

• Coelenterates arc d ploblastic animals, i.e. derived from ectoderm and endoderm.

• The body cavity is known as coelenteron or gastrovascular cavity.


• Presence of peculiar types of cells called cnidoblasts or ncmatocysts or stinging cells in the ectoderm, especially
in tantacles used for offence and defence.

• Hypotoxin is produced by nematocysts.

• Respiration and excretion arc carried out through body
surface by diHusior.

• Reproduction is both sexual and asexual (budding,
e.g. Hydra).


Classification

• On the basis of dominance of medusoid or polypoid phase in the life cycle, phy lum-Coclcntcrata is divided
into three classes

(i) Hydrozoa, e.g. Hydra, Obelia, Physalia.

(ii) Scyphozoa, e.g. Aurelia, Rhizostoma, Cassop1·ea.

(iii) Anthozoa, e.g. Gm·gonia, Mctridium, corals.

• Platyhelminthes (flatworms) include flatworms, which are primitive triploblastic, acoelomate animals with
organ level of organisation.

• Body of these animals is soft, dorsoventrally flattened
leaf-like or ribbon-like.

• No true body cavity or coelom is present.

• Excretion is brought about by special cells called
flame cells or solenocytes, which open through one
or more excretory pores to outside.

• Nervous system is ladder-like, consisting of brain and two main longitudinal nerve cords.

• Animals are generally hermaphrodite.

• Fertilisation is internal.

• In parasitic form suckers, hooks or both arc present
on the head for attachment with the host.

Classification

On the basis of type of life cycle and presence or absence of digestive system, phylum-Platyhclminthes
has been divided into three groups

(i) Turbellaria Dugesia

(ii) Trematoda Fasciola

(iii) Cestoda Taenia


• Taenia solium is a member of Platyhelminthes. Its import;mt characteristics are presence of hooks for
adhesion, presence of digestive system, externally segmented body,etc. It derives it's nutrition from the
host by absorbing nutrients through integuments. Some important Platyhelminthes are.

• Roundworms differ from flatworms in possessing pseudocoelom (pseudocoel).

• Body is usually cylindrical without segmentation.

• Body wall consists of cuticle, epidermis and muscular layer.

• The epidermis is syncytial (multi-nucleated) and without cilia.

• Roundworms are triploblastic (3 germ layers) with bilateral symmetry.

• Digestive system is complete with a mouth and an anus.

• Excretion is brought about by gland cells or intracellular canals or both.

• Regeneration and asexual reproduction are absent.

• The animals are unisexual and exhibit sexual dimorphism.

Classification

Phylum-Aschelminthes has five classes

(i) Nematoda, e.g. Ascaris.

(ii) Nematophora, e g. Nectonema.

(iii) Rotifera, e.g. Philodina.

(iv) Kinorhyncha, e.g. Echinoderes.

(v) Gast:rotricha, e.g. Chaetonotus

• Wuchereria bancro{ti is a digenetic parasite, i.e. it completes it's life cycle in two hosts. The first host is human while
the second host is Culex mosquito. These parasites are found in the blood vessels and lymph of humans and cause
elephantiasis disease.

• Enterobius vcrmicularis is a common worm found parasitic
in children.

Some important nematodes and the diseases they cause are

• Annelids (segmented animals) are triploblastic, bilaterally symmetrical, eucoelomatc (schizocoelia), e.g. earthworms,
leech, etc.

• Body of annelids i> divided into segments called metamerism.

• Many annelids bear fleshy appendages called parapodia,
which are locomotory in function.

• Excretory organs a;:c called as nephridia.

• Annelids usually reproduce sexually.

• The animals arc bisexual/hermaphrodite/monoecious, but
may be unisexual or dioecious.

• They arc oviparous and the eggs are laid in oothecae.

Classification
On the basis of number and presence or absence of setae,
phylum-Annelida is divided into three classes

(i) Polychaeta, e.g. Nereis is unisexual.

(ii) Oligochaeta, e.g. Pheretima (earthworm) is a bisexual.

(iii) Hirudinea, e.g. Hirudinaria (leech) is a bisexual.

• Earthworm (Pheretima posthuma) is a common annelid found in soil.

• It's skin is brown due to the presence of porphyrin pigment. This pigments protect the animal from UV
rays.

• In earthworm, closed circulatory system is present.

• The haemoglobin is usually dissolved in the blood.

• Earthworm is a bisexual animal.

• In cart hworm, testis is present in 1Oth and 11th segment, while ovaries arc present in 13th segment.

• Earthworm docs not undergo moulting.

• They excrete urea.

• Arthropods is the largest phylum of animal kingdom. Members of this kingdom are triploblastic,
haemocoelomic, segmented invertebrates. They have chitinous exoskeleton and joined legs.

• Body is segmented.

• Characteristic of insect is three pairs of legs.

• The body cavity is hacmocoel viz cavity filled with blood.

• Respiration occurs through gills, tracheae and book lungs.

• Blood vascular system is open viz blood does not flow in definite vessels.

• In insects, blood is colourless (haemolymph).

• The cxcreto::y organs are either green glands or Malpighian tubules.

• Moulting, i.e. sheding of chitinous covering occurs.

• The animals are unisexual, i.e exhibit the phenomenon of
sexual dimorphism.

• Fertilisation is internal.

• The animals are oviparous.

Classification

Phylum-Arthropoda is divided into five classes on the basis of body divisions and presence or absensc of certain
appendages

(i) Crustacea, e.g. cancer lobesters.

(ii) Chilopoda, e.g. Scolopendra.

(iii) Diplopod2, e.g. ]ulus.

(iv) Insecta (Hexapoda), e.g. cockroach (Blatta), silverfish,
honeybee, mosquito, etc.

(v) Arachnida, e.g. scorpion, spider.

• Wings are wstigial in female Blatta (cockroach), while silverfish is wingless insect.

• In mosquito., the Johnston's organ (sensitive to sounds) is present in its antenna.

• Mosquito have 15 segments in their antenna.

• Dengue and yellow fever is caused by Aedes mosquito.

• Larva of cockroach and housefly is called maggot.


• Housefly transmits dysentery, typhoid, cholera, etc.

• Honeybees are economically important arthopods as they are reared for the production of honey.

• A colony of honeybees have a queen bee (fertile female), drone bees (fertile males) and worker bees (sterile
females). Males are haploid and females are diploid. Honey is produced by worker bees.

• Molluscs are soft-bodied, unsegmented, triploblastic, coelomate, common!y shelled animals.

• Body is differentiated into bead, foot and visceral mass covered by mantle.

• They are mostly aquatic, both marine as well as freshwater. Some are terrestrial also.

• A hard calcareous shell is secreted by the mantle.

• Coelom is greatly reduced and the body cavity is called haemocoel.

• Exchange of gases ta.kcs place through one or more gills called ctenidia.

• In Mollusca, blood is blue-coloured due to copper containing haemocyanin pigment in plasma.

• Excretion occurs through paired sac-like kidneys (or metanephridia).

• The sexes are generally separate, but some are hermaphrodite.

• Asexual reproduction is absent.

• The larvae of molluscs develop through Velliger, Glochidium and Trochophore stages.

Classification
• Phylum-Mollusca is divided into seven classes

(i) Monoplacophora, e.g. Neopilina.

(ii) Aplacophora, e.g. Chitonderma.

(iii ) Scaphopoda, e.g. Dentalium.

(iv) Gastropoda, e.g. Pila.

(v) Pelecypoda or Lamellibranchiata or Bivalvia, e.g. Unio (freshwater mussel).

(vi) Cephalopoda, e.g. Octopus (devil fish), squid and
cuttle fish, etc.

(vii) Polyplacophora e.o;. Chitum.

• Kokichi Mikimoto of Japan is known as the father of pearl industry.

• Pearl oyster-Pinctad.t vulgaris yields pearl.

• They are exclusively marine, carnivorous and benthonic, i.e. found at the bottom of sea.

• Body shape is cylindrical, globular, star-like or cucumber-like.

• Cephalisation or head formation is absent.

• They have true coelom, which is lined by peritoneum.

• The most feature is presence of water vascular system or ambulacral system.

• They have peculiar to be feet for locomotion.

•lnternal endoskeleton is made up of a calcareous plates called ossicles, derived from mesoderm.

• Respiration takes place through dermal branchiae, peritonial gills and feet.

• Circu.iatory system is reduced and open type. It is known as hacmel system.

• They are dioecious, but there is no sexual dimorphism. Fertilisation is external.

• Life-history usually includes a ciliated larva, such as Bipinnaria, Brachiolaria, Auricularia. Larva undergoes
metamorphosis.

• Phenomena of autotomy (breaking parts to confuse enemy), evisceration (ejection of viscera) and regeneration are common.


Classification

• Phylum-Echinodermata is divided into five classes

(i) Asteroidea, e.g. Asterias (starfish).

(ii) Ophiuroidca, e.g. Ophiothrix (brittle-star).

(iii) Echinoidea, e.g. Ecbimts (sea-urchin).

(iv) llolothuroidea, e.g. Holothuria (sea-cucumber).

(v) Crinoidea, e.g. Antedon (feather-star).

• In starfish, radial symmetry and tube feet are present.

• Hemichordata was earlier placed as a sub-phylum under the phylum-Chordata. But now, it considered as a separate
phylum (under non-chordata). Hemichordates are also called half-chordates. They include small group of
worm-like animals.


• They are exclusively marine and mostly live in burrows.

• Body cavity is true coelom.

• Digestive system is complete, circulatory system is of open
type.

• Sensory cells of the epidermis acts as sense organs.

• Reproduction is mostly sexual. Sexes are separate.

• Rcspiration occurs through several pairs of gill slits or
through general body surface, e.g. Balanoglossus (tongue
worm), Cephalodiscus, etc.

• chordatcs possess three diagnostic features-notochord, dorsal hollow nervous system and pharyngeal gill slits. In
chordates, endoskeleton of bones and cartilages is present. Phylum-Chordata is divided into two groups, on the basis
of presence or absence of skull. These groups are Ac:raniata and Cranita.

• All chordates possess axial skeletal rod of notochord.

• Post anal tail is a chordate character.

Acraniata do not possess skull. They are divided into two sub-phyla.

(i) Sub phylum-Urochordata

• Notochord is present only in the tail of the larva (tadpole).

• Tail may or may not persist in adults. They may show
retrogressive metamorphosis. e.g. Herdmania,
Doliolum, Salpa.

(ii) Sub phylum-Cephalochordata

• Notochord extends throughout the body and persists throughout the life.

• Dorsal hollow nerve cord is present.

• Excretory organs are protoncphridia with solcnocytes.

• Blood is widthout respiratory pigment.

• Heart is absent, but circulatory system is present, e.g.
Branchiostomct.

The members of Craniata possess skull. They are included in sub-phylum vertebrata.

• These are advanced chordates that have cranium (brain box) arounc brain.

• It is believed that all vertebrates are chordates, but all chordates arc not vertebrates.

• Notochord is replaced by vertebral column around spinal cord and cranium around the brain.

• The ndoskdcton is formed of cartilage and bones.

• Heart is ventrally situated. Excretory organs are kidney.

•The sub-phylum has two groups-Agnatha (without jaws) and Gnathostomata (with jaws).

•Gnathostomata is divided into two sub-groups, i.e.
Pisces and Tetrapoda.

• Fishes are cold-blooded animals, i.e. animals whose body temperature varies according to the temperature
of atmosphere typically with backbone, gills and fins.

• The body of a typical fish comprises, the head, trunk and tail. Heart is two-chambered and venous (i.e. only
impure blood flows in the heart).

• Body of a fish may or may not covered by scales.

• Pisces are anamniotes (i.e. without amnion -an extra embryonic membrane), e.g. flying fish (Exocoetu.s
evolans), mosquito fish (Gambusia), sea horse (Hippocampus), Shark (viviparous).

• Tetrapoda is again divided into amphibian>, reptiles,
birds and nummals.

• They are cold-bloockd (poikilothermic) animals, often undercrgoes summer sleep and amphibious in nature, i.e.
aquatic , and terrt'strial habitat simultancously.

• The skill is smooth or rough having glands, which keep it moist.

• The gills are present in larval stage.

• The respiratory organs arc lungs, huccopharyngcal cavity, skin and gil ls.

• The heart is three-chambred. e.g. Rantl tigrina, Bufo melanosticus Alytes.

• Amphibi.1 includes anamniotes (without amnion).

• Hyla is a flying frog.

• Ichtbyphis is a limbless amphibian

• Reptils; are creeping and bu burrowinging cold-blooded vertebrates bearing epidermal scales.

• Respiration always takes place th rough lung.

• Heart consis of two auricles and partly divided ventricle.

• The latcral li ne systt'tl1 is absent .

• Fertilisation is inrernal.

• They are mostly oviparous, e.g. Hemidactylus. draco,
Calotes, snakes (cobra, krait, viper, rattle).

• Snakes are limbless reptiles having poisonous parotid glands.

• Venom of cobra affects nervous system.

• Viper is a non Poiisonous snake.

• Crocodile is a Reptilia, having a four-chambered heart
that store fat in its tail.

• Avls arc anirnab in which forelimbs arc modified into wings.

• These ,are warm-blooded animals, whose body temperature does not vary according to the temperature of atmosphere.

• Exoskeleton is made up of feathers.

• Flight Iiluscks of bird ::u-c attached w keel of sternum.

• The upper , and lower jaws are modified in beak.

• Syrinx is a sound producing organ in birds.

• The alimentary canla has crop and gizzard.

• The heart is four chambcred

• Bone marrow is absent in bones of birds.

• Sexual dimorphism is found, fertilisation is internal.

• AII birds are nviparous.

• The lastcst fly bird is albatross.

• The flights birds are kiwi, emu and penguin.

• Archaeopteis an extinct bird, which is considered as connecting link bctwteen reptiles and birds. lt was only
hird known to have teeth.

• The smallest bird is humming bird. This bird is the only bird that Given fly backward.

• Emu, kiwi and penguin are flight less birds.

• Penguin bird posscsses flipper-like wings. other examples of this class are ostrich, kiwi, penguin,
parrot, ptgcon.

• Dodo bird is the recentntly extincted bird.

• These animal, are hairy and have mammary or milk producing glands. These are warm-blooded animals
whose body temperature docs not vary according to the ternperture of ,Hmosphcrc. They arc the only animals,
which nourish their young ones with milk.

• Heart is four-chambered.

• Teeth are of different types (heterodont) and are embedded in the sockets of jaws (thecodont).

• The skull is dicondylce, i.e. with two occipital condyles.

• The coelom is divided into four cavities, a pericardial catvity, two pleural cavities and an abdominal cavity.

• Fertilisation is internal.

• Most mammals a rc viviparous (giving birth to individuals), e.g. b ngan,o, rabbit (OrJctofagus
mniculus), squirrel (FunmnbulMs penna.ti), human (Homo S'ipiens), dolphin, whale, ~cal and blltS, etc.

• Blue whale gives birth to the biggest baby.

• Spiny ,lntceller and pbtypus are mammals, which lays egg that is oviparous.
Baboon is the largest monkey. .

• Salivary glands arc absent in whales and sea cow.

• Dolphins arc most inlcl)igent, second to man.

• Gorillas do IWt drink WilLer.

• Cow, cunel, etc., arc called ruminants or cud chewing mammals. Their stomach is four-chambered and digestion
d cellulose takes place.

• Two-horned rhino has become extinct from India.

• Fastest mammal-Actinoryx jubatus (cheetah) of Africa.

• The term 'virus' was given by Pasteur. It was discovered by lvanowski in tobacco plant infected
with mosaic disease. Stanley recovered tobacco mosaic virus in crystalline form. H~ later got Nobel Prize in
dangerous and lethal infections, which lead to death of the individual. Mosr of the viruses are known to possess small
fragment of DNA or RNA in single or double-stranded forms covered by means of protein coat called as capsid.
Capsid is made up of smaller units called capsomere. ' A virus consists of approximately 94'% protein and 6%
nucleic acid and arc capable to insert into the DNA of the host organism.
1946. The science dealing ·with the study of viruses is called as virology. They arc intracellular parasites.
They lack cnzyrncs necessary for the generation of energy.

• These are considered as non-living and are dependent on the host for their survival. They exist as crystal--like
forms outside the host and once get inserted, lead to Virus are usuallv 10-300 m!-1 in size. The smallest virus has
size of 20 p. Th~: largest virus is pox virus having a size of 300 mp. They can isodiametric, spherical, polygonal,
anisodiamctric, rod-shaped or thread-like depending upon the shape.