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UNIT-I
Diversity of Living Organisms
CHAPTER-1
THE LIVING WORLD

TOPIC-1
What is Living ?
Revision Notes
 Non-living things do not have life while all living things have life
...

 Characteristics of Living organisms :

l Growth, reproduction, ability to sense environment and mount a suitable response are some unique features
of living things
...

(i) Growth :

l
All organisms (unicellular and multicellular) exhibit growth
...
Growth involves cell division
...


l
Plants grow faster and continuously throughout their life span but animals grow slowly and upto a certain
age
...


l
Some non-living objects like mountains, boulders and sand mounds exhibit an increase in their size, i
...
But this kind of growth exhibited by non-living objects is by accumulation of materials
on the surface
...
Therefore, growth cannot be an all-inclusive
defining property of living organisms
...
Two main
modes of reproduction found in organisms are asexual reproduction and sexual reproduction
...


l
Some organisms like mules, sterile worker bees, infertile human couples, etc
...
Therefore
reproduction cannot be an all-inclusive defining characteristic of living organisms
...

All plants, animals, fungi and microbes show metabolism
...


l
Metabolism is broadly divided into two categories : (i) anabolism and (ii) catabolism
...


l
Metabolism is a defining feature of all living organisms
...
A metabolic reaction preformed in a test-tube (in vitro) is neither living nor non-living but
surely living reaction
...
A cell is an organised structure
...


l
In multicellular organisms, related cells work together to perform a specific function, such a group of cells

is called tissue
...
Various organ systems in
turn together form a complete organism
...
This is known
as organization
...

(v) Consciousness :
l All organisms are sensitive and respond to various stimuli
...

l Animals have sense organs and nervous system and hence they are comparatively more sensitive than plants
...
But human is superior to them because it possess selfconsciousness
...
7-1
...
This refers to biodiversity
...

 Nomenclature :
l Name of an organism in local language of a region is called common name or vernacular name
...
For example, in different countries different languages are spoken and
hence common name of an organism will be different in different countries
...
Therefore,

biologists assign standard names which are used all over the world
...

l For assigning scientific names to plants, principles and criteria are provided in International Code for Botanical

Nomenclature (ICBN) and for assigning scientific names to animals, principles and criteria are provided in
International Code of Zoological Nomenclature (ICZN)
...
The

generic name is always placed first followed by specific name
...
In this name, the first component that is, Mangifera represents the generic name while second
component that is indica is the specific name
...
This was given by Carolus Linnaeus
...

l The first word in a scientific name denotes the generic name while the second word represents the specific
epithet
...
It can be illustrated with the example of Mangifera indica
...

l At the end of the biological name, i
...
, after the specific epithet, name of the author is written in an abbreviated
form, e
...
, Mangifera indica Linn
...

 Classification :
l To study a vast number of different organisms found on the earth, scientists on the basis of similar characteristics
systematically categorised all organisms into various groups and classes
...

l The earliest classifications were based on the ‘uses’ of various organisms
...
It also
helps in knowing features of a group if we know features of any organism belonging to this group
...


l External and internal structure, structure of cell, development process and ecological information of organisms

are the basis of modern taxonomic studies
...

 Systematics :
l The word systematics is derived from the Latin word ‘systema’ which means ‘systematic arrangement of
organisms’
...

l The branch of science in which different features of species, diversities, and relationships with other species
are studied is referred to as systematics
...


TOPIC-3

Taxonomic Categories
Revision Notes
 Classification involves hierarchy of steps in which each step represents a rank or taxonomic category or taxon
...

 Each taxon represents a unit of classification
...
It is a group of individual organisms with fundamental
similarities
...
It consists of a group of related species which has
more characters in common in comparison to species of other genera
...
g
...

 Family : It is a group of related genera with less number of similarities as compared to genus and species
...
g
...

 Order : It is the assemblage of related families
...
g
...

 Class : It is the assemblage of related orders
...
g
...
, is placed in class Mammalia
...
E
...
Classes Amphibia,
Reptilia, Aves, Mammalia, etc
...

 Kingdom : It is the assemblage of various phyla
...
E
...
, Kingdom Plantae, Kingdom
Animalia, etc
...




l Taxonomic studies involve collection of actual specimens of plant and animal species and preservation of

these specimens for future studies
...

l Some of the taxonomic aids used by biologist for identification are herbarium, botanical gardens, museums,
zoological parks, keys, etc
...

l Each herbarium sheet carries a label which has information about date and place of collection, English, local
and botanical names, family, collector’s name, etc
...

(ii) Botanical Gardens :
l These are specialised gardens which have collections of living plants for reference
...

l Some famous botanical gardens are given in the following table
...

l In a museum, specimens can be preserved in the following ways :
(i) They can be preserved in the containers or jars in preservative solutions
...

(iii) Killed and pinned insects are preserved in insect boxes
...

(v) Museums also have skeletons of animals as specimen
...
They enable
us to learn about the food habits and behaviour of animals
...
It is based on the similarities and
dissimilarities
...

l Each statement in the key is called a lead
...

(vi) Other Means of Recording Descriptions :
l Flora, manuals, monographs and catalogues are some other means of recording descriptions
...

l Flora contains the actual account of habitat and distribution of plants of a given area
...

l Manuals are useful in providing information for identification of names of species found in an area
...


Know the Terms
 Growth : It is permanent increase in the cell number and size of the organism
...

 Systematics : The branch of science which deals with different features of species, their diversities, and
relationships with other species is referred to as systematics
...

 Identification : Recognition of a species, by studying easily observable characteristics is called identification
...

 Classification : It is a method by which organisms on the basis of some easily observable characteristics are
categorized into different groups and classes
...

 Phylum : It is a taxonomic category higher than class and lower than Kingdom
...

 Order : It is a taxonomic category which includes related families
...

 Genus : It is an aggregate of related species
...

 Key : It is a taxonomic aid which is used for identification of plants and animals based on similarities and
dissimilarities
...


qq

Oswaal CBSE Chapterwise & Topicwise Revision Notes, BIOLOGY, Class – XI

[ 5

 Nomenclature : The process of assigning a standard name or scientific name to an organism is called nomenclature
...

 Taxon : The unit of classification or taxonomic category is commonly termed as taxon
...

 Class : It is a taxonomic category which includes related orders
...

 Family : It is a taxonomic category which includes related genera
...

 Species : It is the lowest category of biological classification which comprises of related organisms or populations
potentially capable of interbreeding
...

 Monograph : It is a book which contains information about any one taxon
...
He, on the basis of morphological characters,
divided plants into three groups – trees, shrubs and herbs
...

 Two kingdom system of classification

l Linnaeus classified all the organisms into two kingdoms – Plantae and Animalia
...


 Although this system of classification was popular for long time but with the discovery of some new organisms
it was found inadequate
...
Organisms with contrasting characters like eukaryotes and prokaryotes, unicellular and multicellular
organisms and photosynthetic (green algae) and non-photosynthetic (fungi) organisms were placed
together
...
A large number of organisms did not fall into either category
...


 It is a system for classifying biological organisms
...
The domains are Archaea,
Bacteria and Eukarya
...

 Five Kingdom system of classification

 In 1969, R
...
Whittaker proposed a Five Kingdom Classification
...
The main criteria used by him for classifying organisms were
as follows :


1
...
Thallus organisation

3
...
Reproduction
5
...

 The fungi were placed in a separate kingdom – Kingdom Fungi
...

 It has put together organisms which, in earlier classifications, were placed in different kingdoms
...


TOPIC-2
Kingdom Monera and Protista
Revision Notes
Kingdom Monera :
 They are unicellular prokaryotes
...
They are the most
abundant micro-organisms found on the earth
...

 On the basis of shape, bacteria are grouped under four categories :
 Coccus (pL
...

 Bacillus (pL
...

 Spirillum (pL
...

 Vibrium (pL
...

 Monerans have a cell wall which is made up of peptidoglycan
...
Their genetic
material is present in the form of a coiled circular DNA which lies in the cytoplasm
...

 Monerans utilise different strategies to get their food
...
They may be photosynthetic autotrophic or chemosynthetic autotrophic
...

 Bacteria that derive their nutrients from dead remains of plants and animals are called saprophytes
...

 Bacteria that live in association with other living organisms and derive nutrients from them without causing
them harm are called symbionts
...

 The most common method of reproduction found in bacteria is fission
...
This
method of sexual reproduction is called conjugation
...

 Bacteria are further grouped into two groups– Archaebacteria and Eubacteria
...
They are primitive prokaryotes
...
They are found in harsh habitats, such as extreme salty areas-halophiles; hot springs (thermoacidophiles
and marshy areas methanogens
...
Their cell wall consists of non-cellulosic polysaccharides or proteins and lacks peptidoglycan
...

 Eubacteria
1
...

2
...

 Cyanobacteria
1
...
They are found in a wide range of habitats where sufficient
moisture and suitable temperature are present
...


2
...
Some of them are unicellular (e
...
, Chroococcus), some are
colonial (e
...
, Microcystis) while some are filamentous (e
...
, Nostoc, Anabaena)
...

3
...

4
...

 Mycoplasmas
1
...
They completely lack a cell wall and can survive without oxygen
...
Most of the mycoplasma are pathogenic and cause diseases in animals and plants
...
Being eukaryotes, the protistans
contain a well defined nucleus and other membrane-bound cell organelles
...

 Protistans are primarily aquatic
...
They reproduce asexually and
sexually by a process involving cell fusion and zygote formation
...

(i) Chrysophytes
1
...

2
...

3
...
Infact diatoms are the chief ‘producers’ in the oceans
...
The cell walls of diatoms form two thin overlapping shells, which fit together as in a soap case
...
Cell wall of diatom are also rich in silica
...
They
pile up at the bottom of water body and leads to formation of ‘diatomaceous earth’ over billions of years
...


(ii) Dinoflagellates
1
...

2
...

3
...

4
...

5
...
Due to presence of a large number of
red dinoflagellates, the sea appears red (red tides)
...
Red dinoflagellates also release toxins in water which may kill other marine animals
...
Most of them are freshwater organisms found in stagnant water
...
Their body is covered by a protein rich layer called pellicle
...

3
...

4
...
In absence of sunlight, they behave like a predator and feed on other smaller
microorganisms
...
They are saprophytic protists which are found in cool, moist and shady places rich in decaying twigs and
leaves
...
Under favourable conditions they form an aggregation called plasmodium which does not have a definite
shape
...
Plasmodium can move by forming pseudopodia
...
During unfavourable conditions, plasmodium transforms into fruiting bodies which bear spores at their
tips
...
The spores are extremely resistant and survive for many years, even under adverse conditions
...
They are heterotrophs and live as predators or parasites
...
Four major groups of protozoans are given below :
(a) Amoeboid protozoans
1
...

2
...

Example: Amoeba and Entamoeba

(b) Flagellated protozoans
1
...

2
...

3
...

Example : Trypanosoma
...
They are aquatic organisms
...
Their body is covered with thousands of cilia which help in movement and capturing of food
...
A cavity called gullet is present which opens to the outside of the cell surface and is the site of ingestion
...

(d) Sporozoans
1
...

Example : Plasmodium (malarial parasite)

TOPIC-3

Kingdom Fungi and Kingdom Plantae
Revision Notes
Kingdom Fungi
 Fungi prefer to grow in warm and humid places
...
Their bodies consist of long, slender
thread-like structures called hyphae
...

 In some fungi, hyphae are continuous tubes filled with multinucleated cytoplasm
...
In contrast to this in some fungi septae or cross walls are present in the
hyphae
...
Coenocytic means something having multinuclei
...
Chitin is long-chain polymer of N-acetylglucosamine
...
They take their food by following methods :
 Most of the fungi absorb soluble organic matter from dead substrates
...

 Some of them depend on living plants and animals and are called parasites
...
g
...
Fungi live as symbiont
with algae and in mycorrhiza with plant roots
...

 Asexual reproduction : This type of reproduction involves formation of spores which may be of different
types like conidia, sporangiospores and zoospores
...

 In fungi, the sexual cycle involves three steps which are given below :
(i) Plasmogamy : Fusion of the protoplasms of two motile or non-motile gametes is called plasmogamy
...

(ii) Karyogamy : After plasmogamy, nuclei of both gametes fuse together
...

(iii) Meiosis : The last step of sexual reproduction involves meiotic division in zygote
...

 Dikaryophase is a condition of having dikaryon in an intervening dikaryotic stage (i
...
two nuclei per cell) between
plasmogamy and karyogamy in fungi
...

(i) Phycomycetes
 Fungi belonging to this class are found in aquatic habitats and on decaying wood, in moist and damp places or
as obligate parasites on plants
...

 They have aseptate mycelium with coenocytic condition
...
These spores

are produced in sporangium endogeneously
...
Isogamous : Fusion of two gametes which are similar in size
...
Anisogamous : Fusion of two gametes which are dissimilar in size
...
Oogamous : Fusion between one large, non-motile female gamete and a smaller, motile male gamete
...

 Mucor, Rhizopus and Albugo are the common examples of fungi belonging to class phycomycetes
...

 Some of them are unicellular, e
...
, yeast (Saccharomyces) while most of them are multicellular, e
...
, Penicillium
...

 They have branched and septate mycelium
...

Each conidia on germination gives rise to mycelium
...
Ascospores are endogenously
produced in sac like structures called asci and asci are arranged in fruiting bodies called ascocarps
...

(iii) Basidiomycetes
 They grow in soil, on logs and tree stumps and in living plant bodies as parasites
...

 They do not reproduce asexually, but vegetative reproduction by fragmentation is observed in them
...

 Basidium produces four basidiospores exogenously after meiosis
...

(iv) Deuteromycetes
 Sexual or perfect stages of deuteromycetes are not known
...

Because of this they are commonly known as imperfect fungi
...

 They have septate and branched mycelium
...

 Common examples of deuteromycetes are Alternaria, Colletotrichum and Trichoderma
...
They are photosynthetic autotrophs, exceptionally insectivorous
plants such as Bladderwort and Venus fly trap
...

 They have eukaryotic cells with prominent chloroplasts
...

 Plants have two distinct phases in the life cycle– the diploid sporophytic phase and haploid gametophytic
phase
...
This is called alternation of generation
...


TOPIC-4

Kingdom Animalia and Viruses
Revision Notes
Kingdom Animalia
 The members of this kingdom are eukaryotic multicellular organisms
...

 They are heterotrophic and ingest complex organic matter in the form of solid food
...
The digested food is absorbed and utilised by the
body
...
The food reserves are in the form of glycogen or fat
...

 Most of them are capable of locomotion
...


Viruses





 They are non-cellular organisms which remain in inert crystalline form outside the living cell
...
As they infect a cell, they take over the machinery of the host cell to replicate themselves, killing the
host
...
M
...




 Virus means venom or poisonous fluid
...




 D
...
Ivanowsky found that certain microbes caused Tobacco Mosaic Disease in tobacco plant
...
M Stanley showed viruses could be crystallized to form crystals of protein, which are inert outside their

specific host
...
The

genetic material of virus is infectious
...
Viruses
which infect bacteria are known as bacteriophages
...



 The capsid is made of small sub-units called capsomeres which protect the nucleic acid
...
For e
...
The
capsomeres may be arranged in helical or polyhedral geometric forms
...
Infection of viruses

leads to development of diseases in plants also
...

Viroids
 They are infectious agents of plants which are similar to virus but consist of only a short single stranded RNA
...
The RNA of the viroids is of low molecular weight
...

Lichens
They are symbiotic associations between algae and fungi
...
In this symbiotic association both partners are mutually benefitted
...
As lichens
are very sensitive to air pollution and do not grow in polluted area, they are very good pollution indicators
...
It is not surrounded by a nuclear membrane
...

 Parasites : The organisms which obtain their food from other living organisms without killing them are called
parasites
...

 Pellicle : It is a protein rich layer which covers the entire body of members of Euglenoids
...

 Mycorrhiza : It is a symbiotic association of the mycelium of a fungus with the roots of certain plants
...

 Basidiospores : A type of spores which are formed as a result of sexual reproduction in class Basidiomycetes
...

 Capsomere : Small protein subunits of a capsid is called capsomere
...


CHAPTER-3
PLANT KINGDOM

TOPIC-1
Classification of Plants : Algae, Bryophyta and
Pteridophyta
Revision Notes
Types of Classification :
 Artificial System of Classification : It was proposed by Carolus Linnaeus and is based on androecium structure
and vegetative characters
...
D
...
It was based on natural
affinities among organisms
...

This system of classification believes that organisms belonging to the same taxa have a common ancestor
...
In this, numbers and codes are assigned to all
the characters and then data is processed by using computers
...

 Cytotaxonomy is based on cytological information like chromosome number, structure, and behaviour
...

Algae
 They are simple, thalloid, autotrophic and mostly aquatic organisms
...
Some of them are found in association with fungi (lichen) and animals (e
...
, on
sloth bear)
...
Some of them are microscopic unicellular (like Chlamydomonas), some are
colonial (like Volvox) while some are filamentous (like Ulothrix and Spirogyra)
...
All modes of reproduction, i
...
, vegetative, asexual and sexual reproduction are found in
algae
...
In this mode of
reproduction, each fragment develops into a thallus
...
Zoospores are the most common type
of asexual spores
...
They germinate to give rise to new plants
...
On the basis of nature of gamete involved, sexual
reproduction is of following three types :
 Isogamous reproduction : In this type of reproduction, gametes are similar in size
...

 Anisogamous reproduction : This type of reproduction involves fusion of two gametes which are dissimilar in
size as in some species of chlamydomonas
...
Volvox and Fucus exhibit oogamous reproduction
...
About half of the total carbon dioxide fixation on earth is carried out by
algae through photosynthesis
...
These colloids are used
commercially
...
It is used to grow microbes and in preparations of ice-creams and jellies
...

 Some unicellular algae like Chlorella and Spirullina are rich in proteins and hence they are used as food supplements
...

(i) Chlorophyceae (Green algae)
 The members of this class are commonly known as green algae
...
Each chloroplast contains one or more storage bodies called pyrenoids
...
In some algae, food may be stored in the form of oil droplets
...

 Common examples of green algae are Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara
...
Some of them are simple branched, filamentous
forms (like Ectocarpus) while some are profusely branched reaching a height of 100 metres
...
They store food in the form of complex carbohydrates (either
laminarin or mannitol)
...
On the outer side of
the wall a gelatinous coating of algin is present
...
Holdfast keeps the plant attached to the substratum
...


(iii) Rhodophyceae (Red algae)
 They contain a red pigment, r- phycoerythrin in their body and hence they appear red
...
Some of them are found in well-lighted regions close to the surface of water while some
are found at the great depths in oceans where only a little amount of light reaches
...
They store food in the form of floridean starch which is
very similar to amylopectin and glycogen in structure
...

Bryophytes :
 This group includes all mosses and liverworts which are usually found in moist and shaded areas in the hills
...
Hence they are also known
as amphibians of the plant kingdom
...
Plant body is attached to the
substratum with the help of unicellular or multicellular rhizoids
...
The main plant body of the bryophyte is haploid
which produces gametes
...

 Bryophytes possess multicellular sex organs
...
Inside the antheridium, biflagellate antherozoids are developed
and in archegonium, a single egg is developed
...
In archegonium, antherozoid fuses with the egg to produce the zygote
...
As a result a
multicellular body called a sporophyte develops
...
(i
...
, sporophyte is not free-living )
 Some specialised cells of the sporophyte, called sporogenous cells, undergo reduction division (meiosis) to
produce haploid spores
...

 Bryophytes are of slightly less economic importance
...
A moss, named Sphagnum, provides peat that were used as fuel and as packing material
for trans-shipment of living material
...
Mosses along with lichens
are the first organisms to colonise rocks
...

 The bryophytes are further divided into liverworts and mosses :
(i) Liverworts
 The liverworts grow in moist and shady places like banks of water bodies, marshy ground, damp soil, bark of
trees, etc
...
Some of the
liverworts are leafy
...

 Asexual reproduction is by fragmentation of thalli or by formation of gemmae
...
These receptacles are called gemma cups
...

 The male and female organs associated with the sexual reproduction may be produced on the same thalli or on
the different thalli
...
In capsule, development of haploid spores takes
place
...

 E
...
Marchantia
...
Gametophytic phase consists of two stages - the first stage is the protonema stage and the
second stage is leafy stage
...
It is a creeping, green, branched and filamentous stage
...
It consists of upright, slender axis bearing spirally arranged
leaves
...
Leafy stage bears
the sex organs
...

 The mosses exhibit following modes of reproduction :
 Vegetative reproduction in mosses takes place by fragmentation and budding in the secondary protonema
...
e
...
After fertilization
zygote is formed which develops into sporophyte
...
The sporophyte in mosses is more elaborate than that in
liverworts
...
Development of spores involves
meiosis
...
They are mostly found
in cool, damp and shady places
...
Each organ has well-differentiated vascular tissues
...

 The sporophytic plant bears sporangia on the ventral side of leaf-like appendages called sporophylls
...

In sporangia haploid spores are produced by meiotic division in spore mother cells
...
This prothallus is free-living,
mostly photosynthetic and requires cool, damp, shady places to grow
...
The transfer of antherozoids from
the antheridia to the mouth of archegonium requires water
...

 Later on zygote develops into a multicellular well-differentiated sporophyte which is the dominant phase in
the life cycle of the pteridophytes
...
Such plants are called
homosporous
...
Such pteridophytes are known as heterosporous
...

 The pteridophytes are further classified into four classes :
 Psilopsida e
...
Psilotum
 Lycopsida e
...
, Selaginella and Lycopodium
 Sphenopsida e
...
, Equisetum
 Pteropsida e
...
The seeds, which develop
after fertilization, are also naked
...
In some genera, e
...
in Pinus, roots are in association with fungi in the
form of mycorrhiza
...

 In some genera such as Cycas, stems are unbranched whereas in some other genera like Pinus, Cedrus, etc
...

 The leaves may be simple or compound
...

Conifers such as Pinus, Deodar, etc
...
All these
features help to reduce water loss
...
They produce haploid microspores and megaspores within sporangia
...

 The strobili are of two types– male strobili/cones and female strobili/cones
...
The male or
female cones may be borne on the same tree as in Pinus or on different trees as in Cycas
...
The development of pollen grains take place
within the microsporangia
...
The megaspore mother
cell divides meiotically to form four megaspores (n)
...
The female gametophyte is retained within megasporangium
...
They remain within the sporangia retained on the sporophytes
...
When they come in
contact with the opening of the ovules borne on megasporophylls, pollen tube carrying the male gametes grows
towards archegonia in the ovules
...

Subsequently fertilization takes place and a zygote is formed
...
These seeds are not covered
...
Some of them such as
Wolfia are microscopic and some such as Eucalyptus are tall trees reaching a height over 100 metres
...

 Angiosperms are also known as flowering plants
...
Inside the
flower, pollen grains and ovules are developed
...

 On the basis of number of cotyledons present in the seed, angiosperms are classified into two classes– the
dicotyledons and the monocotyledons
...
Each stamen consists of a slender filament with an anther on the tip
...

 Pistil is the female sex organ in a flower
...
Ovary contains one to many
ovules and in each ovule female gametophyte called embryo-sac is present
...

 Dehiscence of anther leads to release of pollen grains
...
, are carried from anther to the stigma of a pistil
...

 On the stigma, pollen grains germinate and leads to development of pollen tube
...
It enters the embryo-sac and discharges two male gametes
...
The second
male gamete fuses with the central diploid secondary nucleus to produce a triploid primary endosperm nucleus
(PEN) which is called triple fusion
...

 After fertilization, zygote develops into an embryo (one or two cotyledons) and the PEN develops into endosperm
...
After fertilization, synergids and antipodal cells
degenerate and ovules develop into seeds and the ovaries develop into fruit
...

(i) Haplontic Life Cycle
In this type of life cycle, sporophytic generation is represented only by the one-celled zygote (2n)
...
Meiosis in the zygote leads to the formation of haploid spores
...
The dominant, photosynthetic phase in such plants is the free-living
gametophyte
...


Zygote
(2n)

Sy

ng

Meiosis

am

y

Spores
(n)

A
Gametogensis
Haplontic

Sporophyte
(2n)

gam

y

Sporophyte
(2n)
A
Meiosis

Zygote (2n)
(a)

y

m

ga

n
Sy
Gametophyte
(n)

Syn

Diplontic

B

Zygote
(2n)

B

A
Gametogensis

Gametogensis
Haplo-diplontic B

Meiosis
(n)

(b)

Spores
(n)

Gametophyte
(n)

Life Cycle patterns : (a) Haplontic, (b) Diplontic, (c) Haplo-diplontic
(ii) Diplontic Life Cycle
In this type of life cycle, the diploid sporophyte is the dominant, photosynthetic, independent phase of the plant
...
This kind of life cycle is
found in gymnosperms and angiosperms
...

In bryophytes, the dominant phase is the independent haploid gametophyte which alternates with the shortlived multicellular sporophyte totally or lived multicellular sporophyte totally or partially dependent on the
gametophyte
...

Examples : Ectocarpus, Polysiphonia, bryophytes and pteridophytes
...

 Anisogamy : It is the fusion of two gametes which are morphologically dissimilar but physiologically similar
(both motile or both non-motile)
...

 Gametophyte : Gametophyte is a haploid plant structure that produces gametes directly by mitosis
...

 Heterospory : It is a phenomenon in which two different kinds of spores produced are borne by the same plant
...

 Triple Fusion : It is the fusion involving two polar nuclei and a sperm nucleus that occurs in double fertilization
in a seed plant and results in the formation of the endosperm
...

The gametophytic phase is represented by the single to few celled haploid gametophyte
...

(iii) Haplo-diplontic Life Cycle
In is an intermediate type of life cycle, where both the sporophyte and gametophyte are multicellular and often
free-living
...

In pteridophytes, the dominant phase is the diploid sporophyte represented by the independent vascular plant
body and which alternates with the multicellular free-living and autotrophic short-lived haploid gametophytes
...


Know the Terms

 Isogamy : It is the fusion of two morphologically and physiologically similar gametes
...

 Oogamy : Refers to the fusion of male and female gametes which are both morphologically and physiologically
dissimilar
...

 Sporophyte : Sporophyte is diploid (2n) plant structure that produces haploid (n) spores by meiosis
...

 Syngamy : It is the process of fusion of the male gamete with the female gamete-egg in an angiosperm
...


qq

CHAPTER-4
ANIMAL KINGDOM

TOPIC-1
Basis of Classification
Revision Notes
 Basis of Classification

 Animals are classified on the basis of following fundamental features :

 Levels of Organisation
1
...


2
...

This type of body organisation is called as cellular level of organisation
...

3
...
Here the cells performing the same
function are arranged into tissues
...
















4
...
Organ level organisation is exhibited by members of Platyhelminthes
...
In higher animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates, organs have associated
to form functional systems
...
This pattern of
level of organisation is called organ system level of organisation
...
Organ systems in different groups of animals exhibit various patterns of complexities
...
This type of digestive system is called incomplete
...

In animals, circulatory system may be of two types – open circulatory system and closed circulatory system
...

Symmetry
1
...
Such type of animals are called asymmetrical
...
In some animals like coelenterates, ctenophores and echinoderms, any plane passing through the central
axis of the body divides the organism into two identical halves
...

3
...
, body can be divided into identical left and right halves in only
one plane
...

Diploblastic and Triploblastic Organisation
1
...
Such animals are called diploblastic animals
...

2
...
This additional layer
is called mesoderm and the animals having such characteristic are called triploblastic animals
...
The body cavity lined by mesoderm is called coelom
...

Annelids, molluscs, arthropods, echinoderms, hemichordates and chordates are the examples of coelomates
...
In some animals, mesoderm is present in the form of pouches in between the ectoderm and endoderm
...
This type of body cavity is called pseudocoelom
and the animals possessing this type of coelom are called pseudocoelomates
...

3
...
Such type of animals are called
acoelomates
...
In some animals, the body is externally and internally divided into segments with a serial repetition
of at least some organs
...

 Notochord

1
...
Notochord is derived
from the mesoderm and located on the dorsal side
...


TOPIC-2

Classification of Animals
Revision Notes
 Phylum Porifera

Members of this phylum are commonly known as sponges
...

They are primitive multicellular animals with cellular level of organisation
...

Flat cells called pinacocytes are present in the pinacoderm and specialised flagellated cells called collar cells or
choanocytes are present in the choanoderm
...
Choanocytes
line the spongocoel
...
Water enters through minute pores called ostia in the spongocoel and from the
spongocoel goes out through the osculum
...

 The body is supported by a skeleton made up of spicules or spongin fibres
...

 They are hermaphrodite i
...
, male and female sex organs are present on the same individual
...
Asexual reproduction takes place through fragmentation
and sexual by formation of gametes
...

 Development is indirect and involves a larval stage which is morphologically distinct from the adult
...

 Phylum- Coelenterata (Cnidaria)
 They are aquatic, mostly marine, sessile or free-swimming animals
...

 They exhibit tissue level of organisation
...

 They possess special cells called cnidoblasts or cnidocytes on the tentacles and the body
...

 They have a central gastro-vascular cavity with a single opening called hypostome
...

 Some of the coelentrates like corals possess a skeleton composed of calcium carbonate
...

 Polyp form : It is the sessile and cylindrical form which is observed in Hydra and Adamsia
...

 Some coelentrates e
...
, Obelia exist in both forms
...
Polyp form reproduces asexually to produce medusae and medusa form reproduces
sexually to produce polyps
...

 Phylum – Ctenophora
 Members of this phylum are commonly known as sea walnuts or comb jellies
...

 They are diploblastic organisms with tissue level of organisation
...

 They exhibit the phenomenon of bioluminescence (the property of a living organism to emit light)
...

 They are hermaphrodite
...
Fertilisation is external and development is
indirect
...

 Phylum – Platyhelminthes
 The members belonging to this phylum have dorso-ventrally flattened body
...







  They possess bilateral symmetry
...

 Most of them are endoparasites
...

 Specialised cells called flame cells are present in them
...

 They are hermaphrodite
...

 Common examples of flat worms are Taenia (Tapeworm) and Fasciola (Liver fluke)
...

 They are found in variety of habitats
...

 They have organ-system level of body organisation
...

 They are triploblastic and pseudocoelomate animals
...

 They have an excretory tube which removes body wastes from the body cavity through the excretory pore
...
e
...
Usually females are longer than males
...

 Some examples of aschelminthes are Ascaris (Round Worm), Wuchereria (Filarial worm) and Ancylostoma
(Hookworm)
...

 They have organ-system level of body organisation
...

 They are triploblastic and coelomate animals
...

 They possess longitudinal and circular muscles which help in locomotion
...

 They possess closed circulatory system
...
nephridium) help in osmoregulation and excretion
...

 Some of them such as Nereis is dioecious, while some such as earthworms and leeches are monoecious
...

 Common examples of annelids are Nereis, Pheretima (Earthworm) and Hirudinaria (Blood sucking leech)
...

 More than two-third of all named species on earth are arthropods
...

 They have bilateral symmetry
...

 Their body is covered by chitinous exoskeleton
...

 They have jointed appendages
...

 They have open circulatory system
...

 They have malpighian tubules as excretory organ
...

 Fertilisation is usually internal
...

 Some of the arthropods such as Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect) are economically
important insects while some other insects like Anopheles, Culex and Aedes (Mosquitoes) are vectors and some
insects like Locusta (Locust) are pest
...

 Phylum – Mollusca
 This is the second largest phylum of Kingdom Animalia
...

 They have an organ-system level of organisation
...

 They are triploblastic and coelomate animals
...

 Their body is differentiated into head, muscular foot and visceral hump
...
The space between the hump and the mantle is called the mantle cavity
...
The mouth contains a rasping organ for feeding, called
radula
...

 Molluscs are usually dioecious and oviparous with indirect development
...

 Phylum – Echinodermata
 The echinoderms are marine organisms which have an endoskeleton of calcareous ossicles
...

 The echinoderms, in larval stage, are bilaterally symmetrical but adults are radially symmetrical
...

 The digestive system is complete
...

 Their unique characteristic is presence of water vascular system
...

 Echinoderms lack excretory system
...
Sexes are separate
...

 Common echinoderms are Asterias (Star fish), Echinus (Sea urchin), Antedon (Sea lily), Cucumaria (Sea cucumber)
and Ophiura (Brittle star)
...
But now it is considered as a separate phylum
under non-chordata
...

 Hemichordates are bilaterally symmetrical, triploblastic and coelomate animals
...

 They have open circulatory system
...

 Proboscis gland is their excretory organ
...
Fertilization is external and development is indirect
...


TOPIC-3
Chordata
Revision Notes
 Phylum-Chordata

 Animals belonging to phylum Chordata are fundamentally characterised by the presence of a notochord, a dorsal
hollow nerve cord and paired pharyngeal gill slits
...
Chordata characteristics
 They are bilaterally symmetrical, triploblastic, coelomate with organ-system level of organisation
...


Table : Comparison of Chordates and Non-chordates
...
No
...


(ii)

Central nervous system is dorsal, hollow and Central nervous system is ventral, solid and
single
...


(iii)

Pharynx perforated by gill slits
...


(iv)

Heart is ventral
...


(v)

A post-anal part (tail) is present
...


Notochord absent
...
Their examples are Ascidia, Salpa and
Doliolum
...
Examples of cephalochordates is Branchiostoma
...
In adults, this
notochord is replaced by a cartilaginous or bony vertebral column
...


l They have a ventral muscular heart with two, three or four chambers
...


l They have paired appendages either in the form of fins or in the form of limbs
...

Section I
...

Class – Cyclostomata

 All the members of class Cyclostomata are marine and ectoparasites on some fishes
...

 They have a sucking and circular mouth without jaws
...

 Their cranium and vertebral column are cartilaginous
...

 They are marine creatures but for spawning they migrate to freshwater
...

 Their larvae, after metamorphosis, return to the ocean
...

Section II Gnathostomata (The jawed Vertebrates) Gnathostomata is divided into two
...

 Their body is streamlined and endoskeleton is cartilaginous
...

 Notochord is persistent throughout life
...

 They contain minute placoid scales
...

 Their teeth are modified placoid scales which are backwardly directed
...
These
animals are predaceous
...

 Their heart is two-chambered (one auricle and one ventricle)
...
g
...
g
...

 They do not have capacity to regulate their body temperature
...

 Sexes are separate
...

 They show internal fertilisation and many of them are viviparous
...


 Class 2 – Osteichthyes

This class includes those marine and freshwater fishes which have bony endoskeleton
...

They possess four pairs of gills which are covered by an operculum on each side
...

They possess air bladder which regulates buoyancy
...

They are cold-blooded animals
...

Fertilisation is usually external and most of them are oviparous
...

Common examples of marine bony fishes are Exocoetus (Flying fish), Hippocampus (Sea horse) while Labeo (Rohu),
Catla (Katla), Clarias (Magur) are examples of freshwater bony fishes
...

Super class 2
...

Class 1
...

 Their body is differentiated into head and trunk
...

 Their skin is moist and lack scales
...

 The eyes have eyelids and tympanum represents the ear
...

 They possess three-chambered heart
...

 They are cold-blooded animals
...
They are oviparous
...

 Some common amphibians are Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander) and Ichthyophis
(Limbless amphibia)
...
– Reptilia
 Members of this class are mostly terrestrial animals and have creeping or crawling mode of locomotion
...

 They lack external ear openings
...

 Most of them possess two pairs of limbs while some do not have limbs
...
(Crocodiles have four-chambered heart)
 They are cold blooded animals
...

 They are oviparous
...













 Some common reptiles are Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard),
Crocodilus (Crocodile), Alligator (Alligator), Hemidactylus (Wall lizard) and poisonous snakes like Naja (Cobra),
Bangarus (Krait), Vipera (Viper)
...
– Aves
 This class includes all the birds which have ability to fly ( except flightless birds like ostrich)
...

 They possess a beak
...

 Their skin is dry and lacks glands but at the base of the tail, oil gland is present
...
The long bones are hollow with air cavities (pneumatic)
...

 Heart is four – chambered
...
Such type of animals are called warm-blooded or
homoiothermous animals
...

 Sexes are separate and fertilisation is internal
...


  Common members of this class are Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo
(Peacock), Aptenodytes (Penguin) and Neophron (Vulture)
...
– Mammalia

 They are found in a variety of habitats like Polar ice caps, deserts, mountains, forests, grasslands and dark caves
...

 They have milk producing mammary glands to nourish their young ones
...

 They possess hair on the skin
...

 They possess different types of teeth in the jaw
...

 They are homoiothermous
...

 Sexes are separate and fertilisation is internal
...

 Common mammals are Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus
(Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera
(Blue whale), Panthera tigris (Tiger), Panthera leo (Lion)
...

Salient Features of Different Phyla in the Animal Kingdom
Phylum

Level of
Organisation

Porifera

Cellular

Coelenterate
(Cnidaria)

Tissue

Ctenophora

Symmetry

Asymmetrical

Coelom

Segmentation

Digestive
System

Circulatory
System

Respiratory
System

Distinctive Features

Absent

Absent

Absent

Absent

Absent

Body with pores and canals
in walls
...


Tissue

Radial

Absent

Absent

Incomplete

Absent

Absent

Comb plates for locomotion
...


Aschelminthes

Organ
system

Bilateral

Pseudocoelomate

Absent

Complete

Absent

Absent

Often worm-shaped elongated

Annelida

Organ
system

Bilateral

Coelomate

Present

Complete

Present

Present

Body segmentation like rings
...


Mollusca

Organ
system

Bilateral

Coelomate

Absent

Complete

Present

Present

External skeleton shell usually
present
...


Hemichordata

Organ
system

Bilateral

Coelomate

Absent

Complete

Present

Present

Worm-like with proboscis,
collar and trunk
...


Know the Terms
 Radial symmetry : It is a type of body symmetry whereby body can be divided into two similar parts by any plane
along oral/aboral axis of body
...













Coelom : It is the space between body wall and gut wall
...

Pseudocoelomate : Animals that have no true coelom
...

Coelomate (True coelomate or Eucoelomate) : Animals that have body cavity completely surrounded by
mesoderm
...

Notochord : It is a rod-like structure formed during embryonic development on the dorsal side
...

Direct development : In this, the young ones resemble the adults in all respects except colour, size
...




---