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BIOLOGY
(ZOOLOGY)
Standard XI

Untouchability is a sin
Untouchability is a crime
Untouchability is inhuman

TAMIL NADU
TEXTBOOK CORPORATION

College Road, Chennai - 600 006
...
T
...
of Zoology
Govt Arts College
Nandanam, Chennai - 600 035
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D
...
M
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Dr
...
Sudarsanam
Reader and H O D
Dept
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Authors
Tmt
...
M
...
G
...
in Zoology
Govt
...
School
Ashok Nagar
Chennai - 600 0083
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T
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G
...
in Zoology
Govt
...
School
Choolaimedu
Chennai - 600 0094
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This book has been prepared by The Directorate of School
Education on behalf of the Government of Tamilnadu
...


Preface
This book has been prepared with an idea that on completion of
the course, the student can opt for any field related to the Biological
Sciences in his / her higher studies
...
The revision of syllabus made,
has provided us with an opportunity to offer adequate information
related to several fields in biology to the students of Higher Secondary
classes
...
A sound
knowledge of the material provided in this book will be essential for
pursuing the next level
...
A list of books for such
reference work is provided
...

Sample questions are provided at the end of each unit
...

As the scope of life sciences is widening due to increasing
demands and ultra developments in all fields, an active, interested
indulgence in the study of Biology will certainly be beneficial
...
Sargunam Stephen
Chairperson
Biology (Zoology)
Text book writing committee
...

Animal groups : Methods of grouping animals - Major Phyla - General
characters with appropriate examples - Protozoa - Porifera - Coelenterata
- Platyhelminthes - Aschelminthes - Annelida - Arthropoda - Mollusca Echinodermata - Chordata
...

Unit II : Cell Biology
Introduction : Microscopy and Cytological techniques
...


Cancer Biology : Cancer definition - Types of cancer - Management of
cancer
...


Unit IV : Genetics
Introduction - Multiple alleles - Quantitative inheritance - Sex
determination - Sex linked inheritance - Pleiotropy
...

Unit VI : Economic Zoology
Beneficial animals : Corals - Earthworm - Vermiculture - Beneficial
insects - Prawns - Lobsters - Crabs - Pearl oysters - Fishes - Guano Aquarium - Vivarium
...

Unit VII : Origin of life
Theories - Geological time scale - Fossils - Extinct animals - Mass
extinction
...

Demonstration - Circulation of Blood in the wing of a live
cockroach
...
Plasmodium - any 2 stages
2
...
Hydra - entire
4
...
Amphioxus - entire
6
...
Frog - Buccal cavity, viscera and Digestive system
...
Upper and lower jaw with dentition
2
...
BIODIVERSITY

1

2
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HUMAN ANATOMY

85

4
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DEVELOPMENTAL BIOLOGY

168

6
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ORIGIN OF LIFE

223

1
...

They live in various environments
...
At present about 2
...
Over 1
...

There are 350,000 species of plants including algae, fungi, mosses and higher
forms of plants
...

The survival of such a vast range of living beings could be ensured
only when their habitats and environmental conditions remain without
alterations
...
It represents a stable environment of
various physical and biological factors which have been operating since the
past
...
The air, the water, the animals, the plants, the microbes and human beings are all interlinked in a life sustaining system, called
the environment
...
The nations of the world have convened
several conferences and adopted important resolutions for safeguarding the
sustainability of earth
...
This conference adopted the motto ‘Only one earth’
...
The UN again
convened “Earth summit” at Rio de Janeiro highlighting “our
common future”, in 1992
...
One of the agenda
commonly placed and accepted in all these meets was the significance of
biodiversity and its conservation to ensure sustainable earth
...
5% of world’s fauna
...
India is one of the 12 countries identified as mega centres of
biological diversity
...
km
...
39 % of the total geographic area of the country
...

Indian flora comprises about 15,000 flowering plants of which roughly
around 1,500 plant species are threatened
...
India’s 1228 bird species represent about 13% of
world’s total
...

Since the world has a vast range of organisms, identifying the useful,
as well as harmful living beings is a need
...
Without proper classification it would be impossible to deal with enormous diversity of life forms
...
1 Taxonomic systems
The initiation for eolving taxonomic systems was provided by Aristotle
(384-322 BC)
...
He observed
insects, fishes, birds and whales
...
Due to his contributions, he is considered as the ‘father
of biological classification’
...
His most interesting systematic work ‘Synopsis
Methodica Animalium Quadrupedum et Serpentini Generis’ was published
in 1693
...
He
also classified animals based on gills, lungs, claws, teeth and other
structures
...

The great Swedish naturalist Linnaeus (Caroli Linnaei) (1707 - 1778)
exerted an important influence on further advancement in taxonomy
...
In 1758 he published his famous
book, systema naturae
...
He followed four categories namely class, order,
genus, species for the animal world
...


2

Michael Adamson (1727 - 1806), a French botanist, stressed that
classification should be based on as many characters as possible
...

Lamarck (1744 - 1829) made the first attempt to improve Linnaen
system
...
He arranged animals according to evolution
...
It was the beginning of
the use of phylogeny in systematics
...
He divided animals into four branches
...

Charles Darwin in 1859, published his famous work ‘Origin of
species’
...
Due to the influence of evolutionary
ideas, taxonomy was studied as an important evidence in favour of evolution
...
A large number of species were
discovered and described
...
During
this period taxonomy was based on population studies
...
Mayr (1942) considered species as “groups of interbreeding natural populations”
...
The taxonomists were forced to accept species as a ‘population’
...

Morphological characters were studied along with other characters as behaviour,
sound, ecology, genetics, zoogeography, physiology and
biochemistry
...


1
...
1 Introduction to taxa and species
While grouping or arranging the organisms, a biologist faces three
scientific ideas, namely taxonomy, systematics and classification
...

The term taxonomy is a Greek word
...
While taxis means arrangement, nomos means law
...
Mayr
1966)
...
It
means ‘placing together’
...
G
...

The term classification in meaning partly overlaps with taxonomy
...
Thus
according to Simpson “Zoological classification is the ordering of animals into groups on the basis of their relationships”
...


Taxon
...
These categories are otherwise called taxa (singular: taxon)
...

The several taxa in animal taxonomy are the Phylum, Class, Order,
Family, Genus and Species
...
In this system each
taxon is based on specific characters of a group of organisms
...
However, human error in identification and grouping may happen
...
There are several such Phyla
constituting the animal kingdom
...

Characters
Single celled animals
Pore bearers
Common body cavity
and digestive cavity
Flatworms
Thread-like worms
Metamerically segmented animal
Having jointed legs
Soft bodied
Spiny skinned
Having notochord

Phylum
-

Protozoa
Porifera

-

Coelenterata
Platyhelminthes
Nematoda
Annelida
Arthropoda
Mollusca
Echinodermata
Chordata

4

Apart from one specific character, the members of the Phylum may
also show other common characters
...
There are only few Classes
in a Phylum
...
Thus for example the Phylum : Protozoa comprises four Classes as
follows
...
It is marked by
some specific feature
...
For example, the
Class : Insecta is subdivided into nearly 29 Orders
...

Order
Aptera
Coleoptera
Lepidoptera
Diptera
Hymenoptera

Character
No wing
Horny wings
Scaly wings
Two winged
Membranous wings

Example
Lepisma
Beetles
Butterflies
Mosquitoes
Wasps
...


5

Each Family will contain several Genera (singular : Genus)
...

In this hierarchy, the Species is considered as the most important taxon
...
All other taxa remain arbitrary and are
subjected to revision
...
It is the
fundamental unit in taxonomy
...
Hence the concept of Species has received much attention
...
However modern workers have identified three
main concepts regarding Species
...
Typological Species concept - This concept has its beginning from the
essentialism concept of Aristotle
...

2
...
Nature produces individuals and not Species
...

3
...
This concept is mostly accepted by present day
taxonomists
...
1
...
Based on overall similarity, identifications are being made
...

The identification method involves measurement of taxon to taxon similarity or dissimilarity
...
‘1’represents
perfect identity
...
In this method
enormous amount of data are collected for related groups
...


1
...
3 Cytotaxonomy
The characterization and identification of a cell’s complete
chromosome set is referred to as karyotyping
...

Karyotypes within interbreeding populations of a species are usually
constant
...
Final stages of chromosomal aberrations such as inversions and
translocations can give clues regarding intermediary stages
...
1
...
Protein fractions in
electrophoretic techniques, identification of amino acids in chromatography,
prevalence of isoenzymes in tissue materials are all tools
employed in chemotaxonomy
...


1
...
5 Palaeotaxonomy
This method depends on identification and dating of fossils
...
In several fossils, their sections taken through laborious processes have provided the identification features
...
Even though it is possible to
assign a fossil to a genus or other higher level, fixing the species is not always
possible
...
1
...
It is an integral part of taxonomy
...

According to Linnaeus a Species is specified by the combination of both its
specific and generic names
...
This system is now firmly established in Biology
...
There are several such commissions
...
Naming of
animals is monitored by International Code of Zoological Nomenclature
(ICZN) (International Commission of Zoological Nomenclature, 1985)
...
The codes are modified by
occasional science congresses
...
Providing stability in the naming and classification of organisms is
emphasized
...

2
...
This system is referred to as the law of priority
...
If two or more workers at one particular time describe the same organism
using different names, it results in synonyms
...
The validity is provided to the senior synonym
...
When names referring to two separate taxa of the same nomenclatural
level are spelt the same, the two names are called homonyms
...
This condition is called homonymy
...

5
...
It
will form the basis for any future identity of a taxon
...
Thus the concept of a genus and species are fixed by their
type genus or type species
...
Names that were used prior to those included by Linnaeus in the “Systema
Naturae”, tenth edition, 1758 are not recognised
...
Scientific names must be either Latin or latinized
...

8
...

9
...


1
...
7 Identification keys
Identification of animals is an integral part of taxonomy
...
Of these, the most commonly used method is, using of keys
...
The construction of the key is an important job of a systematist
...
The language of a key is telegraphic
...
In a bracketed key
alternative contrastive characters are used for identification
...

In an indented key a series of choices are provided for identifying a
taxon
...

The following examples provide the keys for identification four
species of frogs in Tamil Nadu, namely Rana hexadactyla, R
...
cyanophlictis and R
...

The Bracketed key (Genus : Rana)
(1) Large size, snout - vent 100 - 200mm
...
2
(2) Pointed snout
...
limnochoris
(2) Obtusely pointed snout
...
hexadactyla
(3) 4th toe longer than others
...
tigrina
(3) 4th toe not longer
...
cyanophlictis
...
R
...
R
...
R
...
R
...
2 Animal groups
1
...
1 Methods of grouping animals
There are several ways of grouping animals
...
However the taxa are rearranged in
different groups
...

I
...


9

This scheme was provided initially by Aristotle
...

II
...
The
single celled organisms are called the Protozoans
...
In this arrangement among the metazoans the unique
nature of the sponges in not having a tissue grade of body constuction is not
mentioned
...
In yet another method the animals are grouped under following three
assemblages
...
Protozoa - single celled animals
2
...

3
...

Eumetazoa is a large group including most of the multicellular
animals
...

1
...
Ex : Coelenterata
...
Triploblastic animals - having ectoderm, mesoderm and endoderm as three
layers in the body wall
...
1
...
1 Coelomic cavity

The Triploblastic animals are further divided into three groups based
on the presence or absence of an embryonic body cavity called coelom
...
Acoelomata - no coelom Ex : Platyhelminthes
2
...
Coelomata - with a true coelom
IV
...

This system is much more broader including algae, fungi, and plants
...


10

1
...
A
circular DNA occurs in the cytoplasm
...

a) Phylum :Cyanobacteria b) Phylum : Bacteria
...
Kingdom : Protoctista or Protista - It includes single celled eukaryotes
...

3
...
Kingdom : Plantae (green plants)
5
...


1
...
2 Major phyla
Phylum : Protozoa
This phylum includes a great diversity of small, microscopic organisms
...
Their locomotion happens using
pseudopodia, cilia or flagella
...
1
...
2 Protozoans

The nutrition is either autotrophic or heterotrophic
...
Ex : Amoeba, Paramoecium,
Plasmodium
...

These are multicellular, aquatic organisms
...
The sponges belonging to
this phylum are characterised by the presence of a canal system in their
body
...
They can reproduce both by asexual

11

and sexual methods
...


Fig
...
2
...
1
...
4 Coelenterate-body wall

All coelenterates are aquatic animals
...
The
body is radially symmetrical
...
The outer
layer is called the ectoderm
...
The mesogloea is a jelly-like substance
...

Many coelenterates exhibit polymorphism
...
The
ectoderm contains stinging cells called nematocysts (cnidoblasts)
...


12

The layers in the body wall contain several cells and tissues such as
muscle cells epithelial tissues, gland-cells and sensory cells
...
1
...
5 Nematocyst

They reproduce both asexually and sexually
...
In Hydrozoa,
the animal has a dominant polyp body form and a reduced medusa stage
...
g)
Hydra, Obelia
...
1
...
6 Coelenterates

In Scyphozoa the medusa form is permanent
...
They swim in the surface waters
...

The Anthozoans mostly remain as polyps
...

(eg) sea-anemone and corals
...


13

1
...
They are named
as outer ectoderm, middle mesoderm, and inner endoderm
...

2
...

Phylum: Platyhelminthes :This phylum includes flatworms
...
The alimentary canal is either absent or very
simple
...
These worms
are mostly hermophrodites, having both male and female reproductive organs
in a single individual
...
It is divided into
three classes, namely Turbellaria, Trematoda and Cestoda
...
1
...
7 A flame cell

Class Turbellaria :- These are free living aquatic flatworms
...

Class Trematoda :- These are flukes living as parasites inside a host (endoparasites)
...
Flukes
have suckers for attachment to the host tissues
...


Liver fluke
Planaria
Tape worm
Fig
...
2
...
These are internal parasites
with a complex life history
...

Their body characters are adaptations for parasitic life
...
Food is absorbed through general body surface
...
It has a ring of hooks and suckers for attachment to the host tissue
...
(eg) sheep and cattle tape worms
...
The body is narrow and pointed
at both the ends
...
The body is covered by a thin
cuticle
...
The alimentary
canal is a straight tube
...

There are several free living soil nematodes
...

(eg) Ascaris lumbricoides
...
1
...
9 Ascaris

In subsequent Phyla the animals show following general
characters
1
...
Hence these are called as
coelomates
...
The body consists of a series of compartments
...
They have a circulatory system providing internal transport
...
The body segments are rings externally
...
Externally the body is
protected by a cuticle
...
There is a central nervous system
...
The nerve cord is ventral in position
...
These are bisexual and hermophroditic
...


Trochophore larva
Nephridium
Fig
...
2
...
The polychaetes are marine worms
...

There are pairs of lateral projections called parapodia
...

Earthworms are included in the Class Oligochaeta
...
These are blood suckers and ectoparasites
...


Nereis

Leech

Fig
...
2
...
They outnumber all
other animals in population strength
...
It is covered by
a hard exoskeleton made of chitin
...
The legs or paired appendages are jointed
...
Each compound eye is made
up of several photoreceptor sub units called Ommatidia
...
The body
cavity is filled with a fluid called haemolymph
...
These are unisexual, exhibiting sexual dimorphism
...
The larvae undergo
metamorphosis and develop into adults
...
Peripatus shows Annelidan and Arthropoda
characters
...

Class Crustacea :- The examples for this class are prawns, crabs and
lobsters
...


Millipede

Centipede
Fig
...
2
...
These organisms have a distinct head and simple eyes
...
The body consists of numerous segments, bearing pairs of legs
...
1
...
13 Insects

17

Tiger beetle

Praying mantis
1,2 & 3 Insect parasites

Class Insecta :- It comprises the common insects
...
In several insects, the adults have two pairs of wings
on the thorax
...

Class Arachnida :- It includes scorpions, spiders, ticks and mites
...
There are four pairs of
legs attached to the cephalothorax
...
1
...
14 Arachnids - Spiders

Phylum Mollusca :- It is a very successful and diverse group of animals
...
These are soft bodied animals without segmentation
...
The body is covered by
a mantle and a shell
...
The
most common larva is a trochophore larva
...

Class Pelecypoda or Bivalvia :- These are aquatic molluscs having bivalves
...
The body is laterally compressed
...

Class Gastropoda :- These are either aquatic or terrestrial molluscs
...

The foot is large and flat
...
(eg) snails, slugs, and limpets
...
They are adapted for
swimming
...
The shell is either internal or absent
...


18

Chunk
Freshwater mussel

Apple snail

Loligo
Fig
...
2
...
While the adults are
radially symmetrical the larvae remain bilaterally symmetrical
...
They have a water vascular system with tube feet
...
star fishes, brittle stars, sea urchins and sea-cucumbers
...
1
...
16 Echinoderms

Phylum Chordata
This phylum derives its name from one of the common characteristics
of this group namely the notochord (Gr
...
chorda, cord)
...

The backboned animals (vertebrates), together with a few closely related animals which do not possess a backbone, are included in this phylum
...
The chordates
are of primary interest because human beings are members of this group
...
The number of chordate species is limited
...
Despite their modest number of species, the chordates make remarkable contribution to the bio-mass of the earth
...
The vertebrates in particular are considerably larger and many of them are among the largest of living animals
...
The smallest vertebrate , philippine goby is a fish,
measuring only 10 mm in length
...
They have adapted themselves to more modes of existence
than any other group
...

General Characters :
The three distinctive characteristics of the chordates are the presence
of notochord, dorsal tubular nerve cord and pharyngeal gill slits
...
1
...
17 Chordata - a diagrammatic structure
...
Notochord :
During the embryonic development of a chordate there appears a supporting rod called the notochord
...
In some chordates this structure persists throughout
life
...
It is
made up of separate bony elements or vertebrae
...
It is surrounded by
fibrous and elastic sheath
...


20

2
...
It is a tubular structure having a small hollow canal running
from one end to the other
...

3
...
They are present throughout life in fishes and a few tailed amphibians
...
In higher
vertebrates (reptiles, birds and mammals) they are embryonic and non-functional
...
Ventral heart
The heart is chambered
...

5
...

6
...
Thus the
veins originating from the digestive tract as capillaries and ending in the liver
again as capillaries constitute the hepatic portal system
...

The Phylum Chordata is classified into four sub phyla:
Sub phylum 1
...
Cephalochordata
Sub phylum 3
...
Vertebrata
...
Since
the members of these sub phyla do not have a cranium or skull they are also
referred to as Acrania
...

Sub phylum : Hemichordata
...
They are solitary or colonial
forms
...
The body is soft, vermiform,
unsegmented,bilaterally symmetrical and triploblastic
...
The body wall is
composed of single layer of epidermal cells
...
They have
no endoskeleton
...
They have a spacious coelom
lined by coelomic epithelium
...
They are ciliary feeders
...

Examples : Balanoglossus, Saccoglossus
...
1
...
18 Balanoglossus

Sub phylum : Cephalochordata
...
The persistent
notochord extends forward beyond the brain
...
The epidermis is single layered
...

Muscles, nephridia and gonads are segmentally arranged
...
It is a filter feeder
...


Fig
...
2
...
1
...
20 An ascidian

22

Sub phylum : Urochordata
This taxon constitutes a unique group of animals exhibiting diversity in
form and habit
...
The adults are mostly degenerate, sessile forms
...
The free end of the body bears two openings,
the mouth and the atriopore
...
They are hermaphroditic animals
...

Example : Ascidia, Doliolum, Salpa
...

The notochord is an embryonic structure
...
The body is covered
with an integument having an outer epidermis and an inner dermis
...

gill - slits
brain

vertebral column
spinal cord

kidney

mouth
pancreas
heart lungs
liver

gonad

cloaca
urinary bladder

Fig
...
2
...


The digestive system is ventral to the vertebral column
...
The circulatory system consists of the ventral, chamberd heart
...
The blood plasma contains red and white blood corpuscles
...
There are two pairs
of appendages
...
The special organs of sense like the nose, eyes and
ears are closely connected with the brain
...


23

The sub phylum vertebrata may be classified into two groups
(i) Pisces and (ii)
...

Class : Pisces
Fishes are poikilothermic, aquatic vertebrates with jaws
...
It is differentiated into head, trunk and tail
...
Locomotion is effected by paired and median fins
...
1
...
22 Scales

The body has a covering of scales
...
The body muscles are arranged
into segments called myotomes
...
Respiration is performed by gills
...
They may be naked or covered by an operculum
...


Shark

Catla
Fig
...
2
...
The red blood
corpuscles are nucleated
...
The external nostrils do not communicate with the buccal
cavity
...
Sexes are separate
...
Examples: Shark, Catla
...
The limbs are of pentadactyl type
...
The super class Tetrapoda is
divided into four classes namely
...

Class : Amphibia
The living representatives of this class include frogs, toads, newts,
salamanders and limbless caecilians
...
1
...
24 Amphibians

The transition from aquatic to terrestrial living is clearly indicated in
the class Amphibia
...
Amphibians are not completely land adapted
...
This double life is expressed in their name, amphibia
...

The body forms vary greatly from an elongated trunk with distinct
head, neck and tail to a compact, depressed body with fused head and trunk
and no intervening neck
...
In frogs, hindlimbs have webbed feet
...
The slimy nature is due to the presence of mucous secreting glands
...

The mouth is usually large with small teeth in upper or both jaws
...

Respiration is effected by gills, lungs, skin and pharyngeal region
...
The skeleton is mostly
bony, with varying number of vertebrae; exoskeleton is absent
...
Fertilization is either external or internal
...

Examples : Frog, Toad, Salamander, Caecilian
Amniota
The tetrapods like reptiles, birds and mammals are referred to as
amniotes
...
It is an adaptation in terrestrial forms during development
...

Class : Reptilia
Reptiles are represented by lizards, snakes, turtles, tortoises, alligators, crocodiles and the tuatara lizard, Sphenodon punctatum
...
1
...
25 Reptiles

26

The body is variable in shape
...
Skin glands are practically absent
...
The endoskeleton is well ossified
...
The heart is three chambered (In crocodiles it is four chambered)
...
The Sexes are separate
...
The eggs
are covered with leathery shells
...

Example : Garden lizard, Cobra, Monitor lizard, Crocodile, Turtle
...
There are more than 8600 species of birds distributed all over the world
...

Aves are warm blooded vertebrates with an exoskeleton of feathers
forming a non-conducting covering to keep the body warm
...
The forelimbs are modified as wings and provided with
feathers for flight
...
The bones are spongy, containing air-cavities rendering
the body light
...
Only three digits are present in the forelimbs
...
A horny beak is present
...
Inside the body air sacs are
present and some of them communicate with air cavities in the bones
...
The red blood corpuscles are oval and nucleated
...
The ureters open into the cloaca
...
The nervous system is well developed
...
Sexes are separate, Fertilization is internal
...
The egg is covered by a
hard calcareous shell
...
Hence they are known as “glorified reptiles”
...

Class : Mammalia
The term “mammalia” was given by Linnaeus (1758) to that group of
animals which are nourished by milk from the breasts of the mother
...


27

The body is generally covered with epidermal hairs
...
The mammary glands
are modified integumentary glands
...
A muscular diaphragm is present in between thoracic
and abdominal cavities
...
The red blood corpuscles are
non-nucleated, biconcave and usually circular in form
...
Only the left aortic arch is present
...

Corpus callosum, a transverse band of nerve fibres connecting the two cerebral hemispheres, is present
...
Cloaca is absent
...
Eggs are small with little or no yolk
...
Mammals are Viviparous ie
...
Placenta is usually present
...
1
...
26 Mammalian teeth

The class Mammalia is subdivided into three subclasses namely
Monotremata, Marsupialia and Placentalia
...
Sub class : Monotremata or Prototheria

Platypus

Ant-eater

Fig
...
2
...

2
...
The
young ones are born in an immature stage and migrate into the pouch on the
mother’s body
...

Example : Kangaroo

marsupium

Fig
...
2
...
Sub class : Placentalia or Eutheria
In this group eggs develop within the uterus
...

Example : Elephant, tiger, lion, man, monkey, dog, cat , rat, bat
...
This order is of
interest because it includes man, besides lemurs, tarsiers, monkeys and
apes
...
This group stands
first in the animal kingdom in brain development
...
Primates are omnivorous in
habit
...

The neck is mobile
...
The limbs
have five digits and all the digits end in flat nail
...
The brain is highly developed
...
The eyes are directed forward and
the vision is binocular and stereoscopic
...

To know
Scientific Names
Peacock (kæš)
Crow (fhf«)
Sparrow (FUé)
Rat (vè)
Dog (ehŒ)
Cat (óid)
Tiger (òè)
Lion (Á§f«)
Elephant (MÁa ahid)
Man (kåj‹)
Monkey (Fu§F)
Mongoose (Ñç¥ÃŸis)
Bear (fuo)
Fruit bat (gHªÂ‹å btsthš)
Donkey (fGij)
Rhinoceros (fh©lhäUf«)
Spotted deer (òŸë kh‹)
Angel fish (VŠrš Û‹)
Guppy (f¥Ã Û‹)
Apple snail (M¥ÃŸ e¤ij)
House fly (<¡fŸ)
Bed bug (_£il¥ ó¢Á)
Cobra (ešy gh«ò)
Parrot (ȑ)
Garden lizard (Xzh‹)

Pavo cristatus
Corvus splendens
Passer domesticus
Rattus rattus
Canis familiaris
Felis domesticus
Panthera tigris
Panthera leo
Elephas maximus
Homo sapiens
Macaca radiata
Herpestes edwardsi
Ursus arctos
Cynopterus sphinx
Equus hemionus
Rhinoceros unicornis
Axis axis
Pterophyllum scalare
Poecilia reticulata
Pila globosa
Musca nebula
Cimex hemipterus
Naja naja
Psittacula krameri
Calotes versicolor

30

1
...
Type study - 1
...
They cause a febrile disease called malaria
...
Eradication of
malaria is an important problem in public health
...
Malo-bad+air)
...

Its connection with the intermediate host and the modes of transmission
were experimentally worked out in Calcutta by Sir Ronald Ross in 1889
...
Grassi
(1890) provided absolute scientific proof for the specific relationship between
Anopheles mosquito and the human malarial parasite
...

For the completion of life cycle it requires two hosts, a vertebrate and a blood
sucking invertebrate
...
In man, the infection takes place by the inoculation of the slender,
sickle shaped nucleated sporozoite in the blood by the bite of an infected
female mosquito belonging to the genus Anopheles
...
vivax, P
...
malariae and P
...

The life cycle of the malarial parasite involves two hosts, the man and
the mosquito
...
In
man the mode of reproduction is asexual and in mosquito it is sexual
...


Life cycle in Man - Schizogony
There are two phases in the life cycle of malarial parasite in man
...
Erythrocytic cycle or Endo-erythrocytic cycle (inside the red blood
corpuscles)

31

Pre-erythrocytic cycle:
The pre-erythrocytic cycle comprises the asexual reproduction of the
parasite in the liver
...
The sporozoites first enter the capillary vessels of the skin
and then enter the general circulation
...

Sporogony
exflagellation
microgamete

Gametogony
ookinete

zygote
marcrogamete
stomach

oocyst
spore formation

early schizont

sporozoites
food
salivary gland
channel
salivary duct
Endo-erythrocytic
cycle

merozoite
livercell

rupture of RBC
signet ring

RBC

Schizogony

crypto-merozoites

crypto-schizont

Fig
...
3
...
A cryptozoite has a compact nucleus and no pigment or

32

vacuoles
...
When a cryptozoite has reached its full growth it fills the entire cell
...
It undergoes schizogony and the resulting cells known
as crypto-merozoites are set free in the blood by the rupture of the liver
cells
...
This cycle is considered as a period of incubation before the parasites could start the erythrocytic cycle
...


Erythrocytic or Endo-erythrocytic cycle
...
After some time, the parasite gets an amoeboid shape
...
Soon it develops a
vacuole which gradually increases in size
...
This stage is called the signet ring stage
...

This stage is known as the schizont stage
...
These cells are known as
merozoites
...
This causes
the malarial fever
...
This method of infection is known as autoinfection
...

Schizogony keeps up the multiplication of the parasites and their maintenance in the blood
...
The gametocytes are
of two types - marco-gametocytes and micro-gametocytes
...
The micro-gametocyte has a relatively large nucleus and clear cytoplasm
...
If it does not take place they disintegrate
...
But in the gut of the mosquito, only
the mature gametocytes survive and the rest of the stages are destroyed
...
The process of development of gametes from gametocytes is known as gametogony
...
There may be as many
cytoplasmic structures as there are nuclei
...
The resultant cells are called the microgametes
...
The cytoplasm divides unequally
...

The small cell is thrown out
...
The resulting bigger cell is known as female gamete or macrogamete
...
This kind of union is
called syngamy and the resultant form is known as zygote
...

It is known as ookinete
...
There, it ceases to move, becomes
round and forms a membranous cyst-wall
...
It grows in size absorbing the nourishment
from the host
...
Thus inside the oocyst, a large number of cells
develop into minute, slender, sickle shaped bodies called sporozoites
...
They wriggle forward and enter the salivary gland
...
This kind of transmission is called
inoculation
...
It is
charcterised by recurring bouts of fever, each lasting several hours
...

There are four species of Plasmodium known to cause malaria in
man
...
vivax
...
P
...
This type of malaria has a high death rate
...
It is a dangerous species and the disease often
appears in an epidemic scale
...
malariae causes quartan malaria with
feverish fits every fourth day (every 72 hours)
...
ovale
...
America, Russia
and Palestine
...

These four species differ from each other in the details of structure,
time needed to complete the schiogzony, the incubation period, number of
merozoites released and duration of sexual cycle
...

Treatment of infected patient
(1) Plasmodium does not produce antitoxins or antibodies in human blood
...
It can only be treated with drugs that may kill all stages of the
parasite without poisoning the patient
...
The various synthetic drugs, such as Paludrine, Atabrin,
Camoquin, Chloroquine, Resochin, Pamaquin etc are used as suppressants of
various stages of the parasites
...

(i) using protective measures such as mosquito nets, anti-mosquito creams
(repellants) and coils
...


35

(3) Control of vector
It is perfectly clear that if the vector is completely exterminated the
infection cannot be transmitted from one person to another
...
It is achieved by using effective insecticides and by draining swamps
...

Adult mosquito can be most effectively controlled by spraying DDT,
malathion or any other insecticide in the houses; fumigating pyrethrum cresol
and other compounds of naptha; sterilization of male mosquitoes
...


Type study - 2
...
They lie in the burrows during the
day and come out at night for food
...


External features
Lampito (Megascolex) mauritii is a common earthworm found in South
India
...
It is
about 8 to 21 cm long and 3 to 4 mm in thickness
...
It is marked by a
series of segments
...
The division is both external and internal
...
All the segments look alike
...

The mouth is found in the centre of the first segment of the body,
called the peristomium
...
The last segment has the anus
...
In mature worms, segments 14 to 17 may be found swollen with a
glandular thickening of the skin called clitellum
...
1
...
2
...
These pits are called the setigerous pits
...
They are made of chitin and have a swollen middle
part and pointed curved ends
...
They can be moved in any direction and extended or withdrawn
by the action of muscles
...


External apertures :
(i)
...
The coelom communicates to the exterior through these pores and keep the body
surface moist and free from harmful micro organisms
...
Spermathecal openings : Three pairs of openings are situated ventrolaterally in the intersegmental grooves between segments six and seven, seven
and eight and eight and nine
...

(iii)
...


37

(iv)
...

(v)
...


Body wall :
The body wall of earthworm is thin soft and moist
...

Cuticle : It is a thin, transparent, iridescent layer secreted by the underlying
epidermis
...
This layer
contains gland cells and receptor cells
...

Muscles : The muscles are arranged in two layers, namely the outer circular
and inner longitudinal
...


coelom
dorsal vessel

cuticle
epidermis
longitudinal muscle
circular muscle
intestine
setae
ventral vessel
ventral nerve cord

typhlosole
nephridium
chloragogen cells
endodermal lining

Fig
...
3
...
Earthworm-T
...


Body Cavity :
A spacious body cavity called the coelom is seen between the alimentary canal and the body wall
...
The coelom is lined
with the coelomic epithelium and filled with coelomic fluid
...
The fluid oozes out
through the dorsal pores
...
The coelomic cavity communicates to the exterior
through reproductive and excretory apertures
...


Locomotion :
Earthworms move about by contraction and expansion of its body wall
...
This process results in the forward extension of the body
...

Subsequently when the longitudinal muscles contract, the body becomes thick
and shortened
...
Thus by a repeated process of alternate contraction and expansion of muscular body wall locomotion is effected
...
The
mouth is situated in the first segment
...
The buccal cavity in turn leads into a
thick muscular Pharynx
...
The oesophagus is a short narrow tube
lying in 5th segment
...
Its inner
surface has a chitinous lining
...
The intestine upto the 14 th segment is narrow and the
remaining part is sacculated
...
This fold contains blood vessels
...
The inner epithelium consits of columnar cells
and glandular cells
...
1
...
4
...
It takes the soil into its alimentary canal where the organic matter is
digested and absorbed
...


Circulatory System :
In the body of earthworm there are two median longitudinal vessels
...
The ventral longitudinal vessel runs below the alimentary canal
...
There are paired valves inside
this vessel which prevent the backward flow of the blood
...
The ventral vessel has no
valves
...
These vessels run on either side of the alimentary canal and pump blood from the dorsal vessel to the ventral vessel
...
1
...
5
...

The ventral vessel supplies blood to the various organs
...
In earthworm, excretion is effected by minute paired tubes
called nephridia
...

A typical nephridium has an internal funnel like opening called the
nephrostome
...
The nephrostome is in one segment and the
rest of the tube will be in the succeeding segment
...
1
...
6
...
The first part following the nephrostome is ciliated inside
...
The next part is wider and is thrown into coils
...
It is called the glandular region
...
It is called the muscular region
...
The waste material
is collected from the body cavity by the ciliated funnel
...
The glandular part extracts waste from
the blood and add it on to the waste inside
...

In the South Indian earthworm, Megascolex, there are certain modifications
...
They are : (i)
...
micronephridia, (iii)
...

Besides nephridia there are some special cells on the wall of the intestine called Chlorogogen cells
...
These are then sent out through nephridia
...
1
...
7
...
It is a bilobed
mass of nervous tissue situated on the dorsal wall of the pharynx in 3rd segment
...
The brain and the subpharyngeal ganglia are connected by a pair of circum pharyngeal connectives
...
Thus a nerve ring is formed around the anterior region of
the alimentary canal
...
The ventral nerve cord has segmental ganglion one in each segment
...
From each ganglion of
the ventral nerve cord, three pairs of nerves are given off to the body wall and
other organs
...
These receptors are in the
form of groups of slender columnar cells with short hairs projecting at the free
end and connected with sensory fibres at the inner end
...
Gustatory receptors (sense of taste) and
olfactory receptors (sense of smell) are found in the buccal cavity
...
Hence the earthworms are known as hermaphrodites
...
It
is known as protandry
...
Testes are found in segments 10 and 11
...

There are two pairs of seminal versicles formed as outgrowths of the testicular segments
...
The ciliated funnels of the
same side are connected to a long tube called vas deferens
...
Male genital apertures contain penial setae for copulation
...
The prostate glands open to the exterior along with the vas

42

deferens
...


spermatheca
seminal vesicle
seminal funnel

testis
testis

seminal vesicle

ovary
oviduct

vas deferens
clitellum

prostate duct

prostate gland

Fig
...
3
...
Earthworm - Reproductive system

Female reproductive organs
...
They are attached to
the anterior septum of the 13th segment
...
The ova are arranged in a linear order in the
ovaries
...
They open internally into the 13th segment and externally on the ventral surface of the 14th segment
...
These external openings
are situated in the intersegmental grooves of segments 6 and 7, 7 and 8, and 8
and 9
...


Copulation :
clitellum
spermathecal opening
spermathecal opening
clitellum

Fig
...
3
...
Earthworm - copulation

43

Penial setae

During copulation the head ends of the two worms are directed in the opposite
directions and the clitellum of one worm is opposite to the spermathecal segments of the other
...
The worms separate after the mutual exchange of spermatozoa
...

seminal vesicle
testis
seminal funnel
testis
vas deferens
seminal vesicle
Fig
...
3
...
Earthworm - Sperm transfer, storage and fertilization

The girdle is moved forward by the wriggling movements of the body
...
The girdle containing the germ cells (ova and sperms) and the nutrient albuminous fluid is
slipped off at the anterior end and it becomes a closed sac called the
cocoon
...
Young worms come out of the cocoon after complete
development
...
Pigeon
Sub phylum
Class
Order
Type

-

Vertebrata
Av e s
Columbiformes
Columba livia

Birds are easily recongnised group of vertebrates
...
Birds possess feathers,
beak and feet modified in relation to their aerial life
...
They are known both as wild
and domesticated forms
...
About 10 species of Pigeons are found in India
...
The domestic pigeons have many varieties, namely
panter, fantail and tumblers
...
All of them are, however, descendants of the rock pigeon-columba
livia
...

eye
neck
tail further
wing

Entire

leg

claw
beak
toe

cere
Head

Leg
Fig
...
3
...
Pigeon - External

The Body is spindle shaped
...
They
are covered by coloured feathers leaving beak and a small portion of the
hindlimbs
...

The head is round and drawn out anteriorly into a strong, hard, pointed beak
...
The beaks are covered with a horny sheath or rhampotheca
...
It is present on each side
of the upper beak
...
A pair of ear openings are
situated at a short distance behind the eyes
...


45

The neck is long and mobile
...
The trunk is compact, heavy and bears a pair of wings and
a pair of legs
...

Projecting behind the cloacal aperture is the tail
...
It secretes a
fluid used for preening the feathers
...
1
...
12
...
The limbs are of the pentadactyl type
...
The hand has three imperfectly marked digits
...
During flight the
wings are straightened and extended
...
A smaller fold known as postpatagium is present
between the trunk and upperarm
...
1
...
13
...
Each hindlimb or leg has three typical divisions, the
thigh, shank and foot
...
Each hindlimb has four digits
...
The feet are naked and covered with horny epidermal scales
...
The tail is small and concealed by the
feathers of the trunk
...


Exoskeleton :The feathers are integumentary structures
...
The feathers are derived from the epidermis
...

They are arranged on the skin in definite tracts, called feather tracts or pterylae
...

There are three types of feathers in pigeon
...

barb
barbule
hooklet

rachis

barbs
vane or vexillum

Barbs and Barbules

stem
superior umbilicus
aftershaft
quill or calamus
inferior umbilicus
A quill feather
A filoplume
A down feather
Fig
...
3
...
Pigeon - Feather types

47

Quill feather :
Each quill feather has a central stem or scapus
...
The quill has at its lower end an opening called inferior umbilicus,
through which vascular processes or papilla of the dermis project into the
growing feather
...
Close to this opening,
there is a small tuft of soft feathers called aftershaft
...
The rachis with the barbs constitute the vane
or vexillum
...
The barbs
remain attached with one another to form a continuous blade for striking the
air in flight
...
Eleven
of these known as primaries
...
The remaining twelve
fixed on the forearm are called secondaries
...
The tail bears
twelve tail feathers or rectrices which are arranged in the form of a fan
...
These help to keep the body warm and lock air pockets
...
Down feathers have small axis and a few barbs devoid of locking structures at the distal end
...


Endoskeleton :The endoskeleton of pigeon is strong but lightly built
...
Bone marrow is absent
...
The bones are more or
less devoid of bone marrow
...
Most of the
bones except those of the tail, forearm, hand and hind limb contain air spaces
...
It gives
rigidity to the skeleton
...
They are organs of flight
...
Flight is the coordinated effort of a number of paired muscles of
which the following are most important
...
They are about one fifth of the
body weight
...

Pectoralis minor or subclavius :These are smaller but longer than pectoralis major
...

Coracobrachialis :These small flight muscles pull the wing downwards in flight
...
Both the jaws are
devoid of teeth
...
The floor of the
buccal cavity is provided with a narrow, triangular tongue
...
The buccal cavity narrows
behind into the Pharynx
...

Three pairs of buccal glands are present in the mouth
...

The alimentary canal proper starts from the Pharynx
...
At the base of
the neck region, it enlarges into a thin walled, distensible sac known as crop
containing mucous glands
...
The crop is
followed by the stomach
...
The gizzard has a thick muscular wall and a
horny inner lining
...
Thus the gizzard acts as a grinding mill
...
The intestine arises from the right side of the gizzard
...
The
ileum enlarges posteriorly into a short rectum or large intestine
...
The rectum opens to the exterior by the cloaca
...
The
rectum opens into the coprodaem
...
The proctodaem opens to the exterior by a transverse slit like

49

aperture called cloaca
...
Its function is unknown
...
1
...
15
...
The liver is bilobed with a large right and a small left lobe
...
There are two bile ducts
...
They open into the duodenum independently
...
It has three ducts, all opening
into the distal limb of the duodenum
...
Hence, the respiratory system of pigeon is highly
developed and well differentiated
...

The external nostrils are a pair of slit like apertures occurring at the
base of upper beak
...
A
glottis lies behind the tongue
...
The larynx opens into
a trachea
...
On entering the thoracic cavity, the trachea
expands into a syrinx or voice box
...
The walls of tracheal and bronchial tubes are supported by a series
of closely set cartilagenous rings
...
The
bronchus divides and subdivides into smaller branches, ultimately ending in
fine air capillaries
...
They do not hang freely in
the thoracic cavity but are lodged firmly in the ribs
...
There are nine air sacs
...

cervical air sac

trachea
syrinx
air sac in cavity of humerus
inter clavicular air sac

lung

thoracic air sacs

abdominal air sac
Fig
...
3
...
Pigeon - Lungs and air sacs

The air sacs help to maintain high body temperatures
...

Mechanism of Respiration :In birds the expiration is an active process
...
In a resting bird, the sternum is moved up and down with the help
of intercostal and the abdominal muscles
...


Circulatory system :The heart is four chambered, with two auricles and two ventricles
...

Birds have two distinct circulations as arterial and venous systems
...
1
...
17
...
An aorta arises from the left ventricle (right systemic)
...

Venous system :The deoxygenated blood from various regions of the body are collected by several veins
...

jugular vein
brachial vein
pectoral vein
precaval vein
post caval vein
hepatic veins

hepatic vein
epigastric vein
iliac vein

femoral vein
sciatic vein
renal portal vein
internal iliac vein

caudal vein
Fig
...
3
...
Pigeon - venous system

52

Nervous system :The brain is divisible into the fore-, mid- and hind brains
...
They are round and large in size
...
The
diencephalon is hidden from the view by the forward prolongation of the
cerebellum
...
The optic lobes are lateral in
position owing to the large size of the cerebral hemispheres and cerebellum
...
1
...
19
...
There is no external ear
...

choroid coat
iris
cornea

sclerotic coat
retina
pecten
optic nerve

aqueous chamber
lens
sclerotic plate
ciliary process
Fig
...
3
...
Eye of Pigeon

The eyes are large
...
The nictitating
membrane slides over the eyeball and presumably protects the cornea by

53

closing it, during flight
...
It is know as the pecten
...
Its function is not definitely known,
but possibly it may help in long distance vision
...
They are dark red, three
lobed structures
...
There is no urinary bladder
...

ovary
testis
oviducal funnel
kidney
ureter
vasdeferens
seminal vesicle
rectum
cloaca

oviduct
right oviduct

Male

Female
Fig
...
3
...
Pigeon - Urinogenital system

Male Reproductive system :The male has a pair of oval testes
...
The vas deferens is
dilated at its posterior end into a seminal vesicle
...

Female reproductive organs :Only the left ovary persists in the adult
...
The ovary and the oviduct of only oneside are
functional during breeding season
...
The theme of the world summit on environment held in Johennesberg in 2002
was
a) only one earth
b) our common future
c) sustainable earth
d) energy crisis
2
...
If two or more workers describe the same organism using different names it
results in
a) homonyms
b) synonyms
c) a valid name
d) nomenclature
4
...
Five Kingdom concept does not include
a) fungi
b) viruses
c) flowering plants
d) bacteria
6
...
The head formation or cephalization happened for the first time in the Phylum
a) Arthropoda
b) Annelida
c) Mollusca
d) Echinodermata
8
...
The characteristic feature of echinoderms is the possission of
a) compound eye
b) absence of coelom
c) diploblastic conditiond) water vascular system

55

10
...
The segmented body muscles in fishes are called as
a) myotomes
b) smooth muscles
c) skeletal muscles
d) visceral muscles
12
...
The amniotes are characterised by the presence of
a) four legs
b) amphibious life
c) egg membranes
d) metamorphosis
14
...
The infective stage of plasmodium is
a) cryptozoite
b) amoebula
c) sporozoite
d) merozoite
16
...
The muscle fold found in the dorsal wall in the intestitine of the earthworm
is
a) diaphragm
b) Typhlosole
c) myotome
d) ommatidium
18
...
The uropygeal gland of pigeon are found
a) above the tail
b) in the alimentary canal
c) in the brain
d) in the reproductive system
20
...

1
...
Why do we consider Aristotle as the father of biological classification?
3
...
What are triploblastic animals?
5
...
What is a trochophore?
7
...
Why do we call birds as glorified reptiles?
9
...

10
...

11
...
What is Ookinete?
13
...
What are ‘lateral hearts’?
15
...
Provide a breif account on the biodiversity in India
...
What are the various concepts of species?
3
...

4
...

5
...

6
...

7
...

8
...
Provide an account on external openings on the body of earthworm
...
Write notes on flight muscles in pigeon
...
Define species and provide an account on various animal groups
...
Write an essay on the various methods of taxonomy
...
Give a detailed account on the general characters chordates
...
Explain the life cycle of Plasmodium in man
...
Describe the external features of Columba livia
...
Give a detailed account on the reproductive system and the process of
reproduction in earthworms
...


B

A

D
C

F

E
58

2
...
‘The cell is the basic unit of
structure and function’
...
This theory was forwarded by Mathias Schleiden and Theodor
Schwann in 1838 - 39
...

The idea and concept of cell biology evolved during the 19th century
as a result of gradual advancement in the field of microscopy and biochemistry
...
Due to its wide application many
new branches have sprung up in biology
...


2
...
The small
dimensions and transparent nature of cell and its organelles pose problems to
cell biologists trying to understand its organisation and functioning
...

The diameters of majority of cells range from 5-500 µm, but most are
between 10-150 µm
...
It is sometimes used to record the
thickness of cell membranes and the sizes of macromolecules
...
The ability to reveal minute details is expressed in terms of
limit of resolution
...
The
resolving power of naked human eye is 0
...
It means that we
cannot differentiate any points that are closer than this
...

Power of magnification is different from resolving power
...
Increased magnification without improved resolution results only in
a large blurred image
...

The first useful compound microscope was invented by Francis
Janssen and Zacharias Janssen in 1590
...
Galileo Galilei (1564-1642) invented a
simple microscope to study the compound eye of insects
...
Marcello Malpighi (1628-1694) an Italian
microanatomist used a microscope to study organ tissues of animals
...
He coined the term “cells” to honey
comb of cells in cork tissue
...
2
...
1
...
His microscopes achieved magnification upto 300x
...

Further advancements in cell biology were made by improving the
quality of compound microscopes
...
It
contains glass lenses that magnify the image of the object and focus the light
on the retina of the observer’s eye
...
The lens closer to the object being viewed is called objective
lens
...
The object
is illuminated by light beneath it
...


Dark field microscope
This type of microscope is useful for viewing suspensions of bacteria
...
The result is an image that appears bright against a
dark background, with a high degree of contrast
...


Phase contrast microscope
The phase contrast microscope has special fitments to the objective
lens and sub stage condenser, the effect of which is to exaggerate the
structural differences between the cell components
...
Phase contrast microscopy avoids the need to kill cells
or to add dye to a specimen before it is observed microscopically
...
Normally the technique is used to view permanently mounted
specimens
...


61

Electron microscopy
...
Electromagnetic coils (ie
...
The electrons are made to pass through the specimen
...
Finally a
magnified image is produced by a projector coil or ‘lens’
...
This type of electron microscope is called transmission
electron microscope (TEM)
In a compound light microscope, the image is formed due to
differences in light absorption
...


cathode shield
tungsten filament
anode

eyepiece lens

condenser lens
specimen
holder

specimen
objective lens

binocular
viewer
objective lens
specimen
stage

projector lens

condenser
lens

image
fluorescent screen
camera
Electron microscope

tungsten
filament
lamp

Light microscope

Fig
...
1
...
Comparison of the components and pathways of radiation

62

The degree to which electrons are scattered is determined by the thickness and atomic density of the object
...
Living cells which are wet cannot be
viewed in electron microscope
...
, about
200Å)
...
The whole specimen is scanned by a beam of electrons
...

Scanning electron micrographs show depth of focus and a three dimensional
image of the object
...
1
...
They
can be observed either directly or after preservation
...
Direct observation is possible by
using vital stains
...
They selectively stain intracellular structures without affecting cellular
metabolism and function
...

Preserved and stained tissues :- For detailed microscopic study, tissues
containing cells are passed through various stages
...

1)
...
A good fixative prevents bacterial decay and autolysis
...
The
commonly used fixatives are Acetic acid
...

2)
...
It is done by using ethanol and benzene
...
Embedding :- The tissues are infiltrated with molten paraffin wax
...
Very
thin sections need to be taken for electron microscopy
...

4)
...
It is done by using an instrument called microtome
...
Staining :- The sections are immersed in dyes that stain some structures
better than others
...
Nucleus
stains blue with haematoxylin or red with safranin
...
Dehydration :- Stained sections are immersed in ethanol to remove water
...
Dehydration is done gradually by
using a series of increasing concentrations of ethanol in water
...

7)
...
A cover slip is added and the medium is allowed
to dry
...
2
...
3
...
2
...
It is an ultra thin, elastic, living membrane
...

Since the plasma membrane is ultra thin, it could be observed only
under electron microscope
...

In 1895 Overton suggested that the membrane is made of fatty substances
...
According to a model proposed by Danielli and Davson
in 1935, the lipid bilayer of the membrane was coated on either side with
protein
...
2
...
1
...
According to this hypothesis the two outer layers of
protein are about 2 nm thick and appear densely granular
...
5 nm wide consisting of lipids
...

cell coat

glycoprotein

cholesterol

glycolipid

lipoprotein bilayer
phospholipid

sphingolipid

Fig
...
2
...
The fluid-mosaic model of the cell membrane

65

Singer and Nicholson (1972) have proposed a fluid mosaic model
for the plasma membrane
...
In this structure much of the protein molecules float about
...
Lipid molecules also move
about
...

The cell membrane controls the passage of materials both into and out
of the cell
...
Water
passes through the membrane by Osmosis
...
Many water soluble solutes are transported by carrier proteins
...


2
...
2 Mitochondria
The mitochondria are filamentous or granular cytoplasmic organelles
of all aerobic cells of higher animals and plants
...

They were first observed by Kolliker in 1850 as granular structures
in the striated muscles
...
Various steps of glycolysis in mitochondria was discovered by two
German biochemists Embden and Meyerhof
...
Sir Hans Adolph Krebs, in 1937 found out various reactions of citric
acid cycle
...

The number of mitochondria in a cell depends on the type and functional state of the cell
...
g
...
Oocytes of
amphibians contain 300,000 mitochondria
...
Some algal cells may contain only one mitochondrion
...
They vary
in size from 0
...
0 µm
...

Each mitochondrion is bound by two highly specialized membranes
...
It is separated from the inner membrane by a
6-8 nm wide space
...


66

inner
membrane
matrix

intercristal space

outer
membrane
intercristal
space
oxysomes
A Crista

cristae

Fig
...
2
...
Three dimensional structure of a mitochondrion

Thus mitochondria are double membrane envelopes
...
The outer
compartment is the peri-mitochondrial space
...
The inner compartment is the matrix space
...
The matrix
contains lipids, proteins and circular DNA molecules
...
Hence the mitochondria perform several important functions such as oxidation, dehydrogenation, oxidative
phosphorylation and respiratory chain of the cell
...
2
...
4
...

During such biological oxidations large amount of energy is released
...
Due to this function, the
mitochondria are also known as “power houses” of the cell
...


67

2
...
3 Ribosomes
The ribosomes are small dense, rounded and granular particles
...
They occur either freely in the matrix of the mitochondria, chloroplast and cytoplasm or remain attached with the membrane
of the endoplasmic reticulum and nucleus
...
E
...
The name
‘ribosome’ was coined by R
...
Roberts in 1958
...
In the
cells in which active protein synthesis takes place, the ribosomes remain attached with the membranes of the endoplasmic reticulum
...


sub-units

Fig
...
2
...
Ribosome

The ribosomes are spheroid structures with a diameter of 150 to 250
Å
...
One subunit is large in size
and has a dome like shape
...

The ribosomes are chemically composed of RNA and proteins
...
The ribosomal proteins enhance the catalytic function of the rRNA
...


68

2
...
4 Endoplasmic Reticulum
...
Since these structures
are concentrated in the endoplasmic portion of the cytoplasm, the entire
organisation is called the endoplasmic reticulum
...

The occurrence of ER varies from cell to cell
...

The ER is the site of specific enzyme controlled biochemical
reactions
...
The presence of
ribosomes gives a granular appearance
...
RER is the site of synthesis of proteins
...
SER is concerned with lipid metabolism
...
Lamellar form
2
...
Tubular form
...
2
...
6
...
Their
diameter is about 40-50 µm
...
It is mostly seen
in cells of pancreas, notochord and brain
...
Their diameter is about
25-500 µm
...

Tubules :- These are branched structures forming the reticular system along
with the cisternae and vesicles
...
They
occur in almost all cells
...
It provides skeletal framework to the cell
...
It facilitates exchange of molecules by the process of osmosis, diffusion
and active transport
...
Enzymes of ER control several metabolic activities
...
They serve as intracellular transporting system
...
It conducts intra-cellular impulses
...
It helps to form nuclear membrane after cell division
...
SER synthesises lipids
...
2
...

The Golgi apparatus occurs in almost all animal cells except red blood
cells
...
Some cells have
more of Golgi apparatus
...
In nerve cells it occupies a circum-nuclear
position
...
A cisterna is
about 1 µm in diameter
...
This space accumulates secretions
...
In the lamellar arrangement the space
between each cisterna is 20-30 nm
...
A group of dictyosomes constitute the Golgi apparatus
...
2
...
7
...

The Golgi apparatus is the site of synthesis of biochemicals
...


2
...
6 Lysosomes
These are tiny vesicles surrounded by a membrane
...

Lysosomes were initially named as ‘perinuclear dense bodies’
...
de Duve in 1955
...
However they are not found in
mature mammalian erythrocytes
...

They are numerous in epithelial cells of secretory and excretory organs
...
It is filled with a dense material
...
Their size ranges from 0
...


71

Recent studies reveal that lysosomes may contain upto 40 types of
hydrolytic enzymes
...

discharge
digestion
entry of solid matter

Lysis

Lysosome

golgi apparatus

functionless organelle

Fig
...
2
...
Lysosomes - in action

Lysosomes originate either from the Golgi apparatus or directly from
the endoplasmic reticulum
...
For example, when an animal cell ingests food into a food vacuole, lysomes fuse with the vacuole and break down
the contents
...
The glands
in some digestive organs package their digestive enzymes in lysosomes before
releasing them outside the membrane
...


Peroxisomes
These are spherical organelles bounded by a single membrane
...
The name peroxisomes was coined by C
...
Baudhuin
(1966)
Peroxisomes contain catalase, an enzyme that catalyses the decomposition of hydrogen peroxide to the harmless products, water and oxygen
...
It is
potentially a very harmful oxidising agent
...
2
...
When a centriole supports a flagellum or cilium, it is called the
basal body
...
They are absent in prokaryotes, red algae, yeast cells and flowering
plants and some non -flagellated or non-ciliated protozoans
...
15-0
...
They are
usually 0
...
7 µm in length
...
Each microtubule has a diameter of 200260 Å in diameter
...

It was initially considered that new centrioles arise by the division of
existing centrioles
...
It appears that new centrioles are produced de novo or are synthesized using an existing centriole as
a template
...
The centrosome organizes cytoplasmic microtubules during
interphase in mitosis
...

The centrioles form the basal body and the cilia
...
The centrioles are also involved in ciliary and flagellar activity
...
2
...
It controls all metabolic processes and hereditary activities of the cell
...
The occurrence of a nuclear membrane was first revealed by O
...

The nucleus is found in all the eukaryotic cells of plants and animals
...

Usually the cells contain single nucleus (mononucleate)
...
Accordingly they may be called
binucleate or polynucleate cells
...

In certain cells the nucleus is irregular in shape
...
The
size is directly propotional to that of the cytoplasm
...
The nucleus of the haploid cells are smaller than that of the diploid cells
...
2
...
9
...
2
...
10
...
This envelope is
comprised of two membranes of 5-10 nm thickness
...
The inner
nuclear membrane is surrounded by the outer nuclear membrane
...
It is
a 10 to 50 nm wide fluid filled compartment
...
It is a very dynamic
structure
...
Each pore has
a diameter between 10 nm to 100 nm
...
There is continous movement of molecules across the nuclear envelope through the pores
...
The chromatin threads and the nucleolus remain suspendended in the nucleoplasm
...

The nucleoplasm contains several thread like coiled structures
...
During the cell division they become thick ribbon
like structures known as chromosomes
...

The nucleus contains one or more spherical colloidal structures called
nucleoli
...

The number of nucleoli in the cells may be one, two or four
...

Ribosomal subunits are synthesized in the nucleolus
...


Chromosomes
The chromatin fibres get condensed into chromosomes during cell divisions
...

The nucleus was first observed and described by karl Nagli (1842) in
the nuclei of plant cells
...
Schneider (1873)
...
T
...
Muller in 1922 revealed the occurrence of nearly 2000 genetic factors on four chromosomes of Drosophila
...

The number of chromosomes is constant for a particular species
...
It is also known as the genome
...
The diploid condition is arrived at by the union of the
haploid male and female gametes in the sexual reproduction
...
aurelia

30-40

Hydra

H
...

It may range from 0
...

A

B

C

D

Fig
...
2
...
Types of chromosomes
A - Telocentric, B - Acrocentric, C - Submetacentric, D - Metacentric

The shape of the chromosome changes from phase to phase
...
The centromere divides the chromosome into two parts
...
Thus according to the position of the centromere and nature of the chromosome arm, the chromosomes may be Telocentric, Acrocentric, Submetacentric and Metacentric
...
3 Cancer biology
2
...
1
Cancer is a proliferation of cells which grow in an uncontrolled
manner, invading local tissues and spreading widely through the blood or lymphatics to produce secondary deposits, or metastases in distant parts of the
body
...
A tumour was
called a cancer because of swollen veins around the area resembling a crab’s
limbs
...
Oncology is a word derived
from the Greek, onchos, a lump, or tumour
...
If a neoplasm can cause harm by spreading, it is said to be
malignant
...
However the disease as it
would be defined today was established as an entity by German pathologists
of 19th century
...
At the beginning of the 20th century, most major forms of cancer had
been described
...
In 1775 Pott recognised cancer in chimney sweeps
...
From this time onwards environmental and occupational hazards were recognised as follows :
shale oil

skin cancer in workers

radio active ores

lung cancer in miners

beta-naphthylamine

bladder cancer in rubber industry workers

cigarettes

lung cancer

Later it was discovered that certain viruses can also cause cancer
...

Recently, human T-cell leukaemia has been found to be due to the virus
HTLV-1
...
A rare eye tumour,
retinoblastoma is inherited
...

Cancer biology
The knowledge of cancer biology is growing rapidly
...
The available information is not sufficient for satisfactory
treatment of cancer
...
The processes of cell mitosis, growth and differentiation are controlled by cellular
genes
...

such a mutation can happen in a single cell
...
With further growth of cancer, additional mutations may occur in the
daughter cells giving rise to subclones
...
Among these subclones some may have greater
capacity and metastasize to distant tissues
...

The cancer cells have characteristic properties
...
These cells have
large nuclei
...

They have prominent nucleoli
...
As component cell of a tissue they remain less differentiated
...
Cancer cells have the ability to invade surrounding
tissues
...
The process of carcinogenesis includes, intiation,
growth, promotion, conversion, propagation and progression
...

Mature cancers have relatively uncontrolled growth, behaviour
...
Initially the cancer cells have an
exponential growth
...

This results in slowing down of growth
...
It has been found that at molecular level
two mechanisms operate
...
The parts of genome involved in cell growth become activated
...
These strands of DNA induce malignant growth
tranformation in the cells
...
Further such cancer cells dis-

78

play chromosomal abnormalites such as duplication, deletions and translocations
...

Oncogenes of human tumours
Oncogene

Type of cancer

Activation mechanism

hox11

Acute T-cell leukemia

Translocation

erbB-2

Breast and ovarian carcinomas

Amplification

L-myc

Lung carcinoma

Amplification

ret

Thyroid carcinoma DNA

rearrangement
...
It results in elevated gene expression
...
It occurs a thousand times more
frequently than in normal cells
...

2
...
In cancer,
parts of the genome functioning as the suppressor gene are either lost or
inactivated
...
It
contributes to the abnormal proliferation of cells
...


The protein products of the tumor suppressor genes normally inhibit
cell proliferation
...

The complete sequence of events required for the development of any
human cancer is not yet known
...
Simultaneous effect on both the genes

79

will result in multiple genetic defect
...


2
...
2 Types of cancer
Cancers are named according to the tissues from which they arise
...
Sarcoma - Malignancy in structural tissues Ex: Osteosarcoma (bones),
liposarcoma (fa)
...
Carcinoma - Epithelial cancers
...

3
...
Leukemia - White blood cells
...

1
...
Atleast 90% of lung cancer deaths are due to smoking
...
Snuff and chewing tobacco can affect mouth and
respiratory tracts
...

2
...
These radiations rupture DNA strands, causing mutations
...

3
...
Dietary substances such
as fat, high calorie intake of animal proteins, salted or smoked food can cause
cancer in Breast, Colon, Stomach and Oesophagus
...
Certain drugs if taken without medical advice can cause cancer
...
Viruses and parasitic organisms like schistosoma, liverfluke can also
affect
...
It is because
of the unique characteristics of the cancer cells
...
However the cancer cells do not require the
growth factors
...


80

Normal cells have a nature of remaining together in tissues
...
Hence they wander through the
tissues and enter the blood
...

The cancer cells rapidly multiply
...

Thus these cells will drain all the nutrients and normal cells get deprived of
food
...


Management of cancer
The treatment or management of cancer depends on an accurate diagnosis
...

In order to compare results and for communicating treatment
programme among medical personnel staging systems are essential (Ex:
stage1, stage2) staging defines tumours as either confined to the tissue of
origin or having spread to local tissues and organs and finally as having
metastasized
...

Till last century, surgery was the only effective method of treatment
...
If the tumour is restricted to the primary site, through surgery it can be removed
...

Radiotherapy :- Discovery of x-rays by Roentgen(1895) and of radioactivity
by Curies in 1899 opened new ways of treating cancer
...
The radiations used are x-rays and gamma
rays or subatomic particles such as beta particles, high energy electrons and
neutrons or charged particles like helium ions
...
They can damage DNA leading to cell death and
mutagenesis
...
Hence the aim of
radiotherapy is to prescribe sufficient radiation dose to the tumour, sparing as
much of the normal tissue as possible
...
The chemicals used in treatment
affect cell multiplication and tumour growth
...
They can used singly or in combination
...
Hence hormones are used in their management
...
Primary prevention of cancer will be a better
alternative to diagnosis and treatment
...
Hence public awareness towards environmental issues
is a need
...
Hence smoking
cessation and other measures to reduce tobacco usage are to be insisted upon
...

Thus it is apparent that fight against cancer will be successful with
early detection and appropriate education for avoidance
...
Living cells which are wet cannot be viewed in a / an
a) Compound microscope
c) Electron microscope

b) Phase - contrast microscope
d) Dark - field microscope
...
The increase in size of optical image over the size of the object is known as
(a) limit of resolution

(b) transmission

(c) power of magnification

(d) conductance

3
...
In a microscope the light is focussed on the object through
(a) condenser lens

(b) objective lens

(c) occular lens

(d) oil immersion lens

5
...
In microscopy a nucleus is normally stained using
(a) Neutral red
(b) Janus green B
(c) Eosin
(d) Hematoxylin
7
...
A unit membrane hypothesis for plasma membrane structure was provided by
(a) Overton
(b) Daveson
(c) Robertson
(d) Nicholson
9
...
The role of mitochondria in oxidative phosphorylation was explained by
(a) Leninger
(b) Embden
(c) Krebs
(d) Meyer hoff
11
...
The ribosomes are meant for
(a) phosphorylation
(b) respiration
(c) protein synthesis
(d) oxidation
13
...
Which of the following cell may not contain golgi apparatus
(a) epithelial cells
(b) glandular cells
(c) RBC
(d) secretory cells
15
...
The movement of the flagellum is regulated by
(a) plasma membrane
(b) nucleus
(c) basal body
(d) ribosomes

83

17
...
Write a note on phase contrast microscope
...
What is ‘limit of resolution’ in the functioning of a microscope ?
3
...

4
...
Name two biochemical processes happening within the mitochondria
...
What are RER and SER ?
7
...
When do we call centriole as a basal body
...
What are the types of chromosomes based on the nature of their arm ?
10
...
Write notes on cell theory
...
Explain the various units of measurement in cell biology
...
Differentiate TEM and SEM
...
Provide the structure of the golgi apparatus
...
Write notes on the organisation of a centriole
...
Give an account of types of microscopes
...
Describe how a specimen is prepared for microscopic study
...
Write an essay on structure and functioning of mitochondria
...
Provide a detailed account on the organisation of cell nucleus
...
Human Anatomy
3
...
History of Human anatomy
The term ‘anatomy’ is Greek in origin
...
Thus anatomy is the science of physical
structure of an animal or plant studied by dissection
...

The study of human anatomy dates back to 2500 BC, when the
Egyptians prepared mummies
...
They also did surgery for wounds and broken bones
...
In 1st century AD,
Celsus, a Roman physician wrote about surgical procedures
...
In 1628 William Harvey described the
functioning of heart and the movement of blood in animals
...
In the recent times, attempts are being
made to understand the molecular architecture in every cell of our body
...
The first
edition of this book was published in August 1858
...
A more elaborate 38th edition
was published in the year 2000
...
He
lived upto 1861
...
George’s
Hospital, London
...
1
...
The integumentary system covers the outside of the body
...
Since the
integument performs several functions, it is commonly referred to as Jack of
all trades
...

The hypodermis attaches the skin to underlying bones and muscles
...

hair
sebaceous gland

epidermis
arector pili (smooth
muscle)
hair follicle

dermis

nerve
blood vessels

sweat gland

fat

hypodermis
Fig
...
1
...
Skin and hypodermis

The skin is composed of two major tissues, namely dermis and
epidermis
...
It provides the structural strength to
the skin
...

It is divided into two layers, namely the superficial papillary layer
and deeper reticular layer
...
The reticular layer is the major layer of the dermis
...

It is continuous with the hypodermis
...
It
is separated from the dermis by a basement membrane
...
Many of the cells of the epidermis produce
a protein substance called keratin
...

keratin
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
papilla

Fig
...
1
...
Epidermis

basement membrane

The deepest layers of the epidermis produce nerve cells by mitosis
...
The surface cells will protect the inner new cells
...
Slowly they get filled with keratin
...
During this process the epidermis gets
divided into five distinct regions or strata
...

Stratum basale is in the deeper region of the epidermis
...
Keratinization of cells begins in this region
...
It has 8-10 layers of polygonal cells
...
It has 3-5 layers of flattened cells
...
It is a thin zone having
several layers of dead cells
...
It consists of more than 20 layers of dead cells
...
They are said to be cornified
...

The skin can be either thick or thin
...
However stratum corneum contains more number of cells
...
The general body surface has thin skin
...
There are only one or two layers of
cells in stratum granulosum
...
The callus has several layers of cells in the
stratum corneum
...
The
thickness of the stratum corneum and blood circulation can also cause skin
colour
...
It provides
colour to skin, hair and eye
...

Melanin is produced by melanocytes
...
However, hormones and exposure to light can also alter the colour
...
A hair has a root and a shaft
...
The base of the root has a hair bulb
...
The shaft
and most of the root of the hair are formed of dead keratinized epithelial cells
...
The central axis of the hair is formed of the medulla
...

medulla
cortex

hair

cuticle
internal epithelial root sheath
external epithelial root sheath
dermal root sheath
Fig
...
1
...
Cross section of a hair within a follicle

According to the amount and types of melanin, the hair colour may
vary
...
During old age the
amount of melanin decreases causing white hair
...

The hair growth is due to addition of cells at the base of the hair root
...
After a resting period, new hair replaces
old hair
...

88

The muscle cells found associated with hair follicles are called the
arrector pili
...

The skin has sebaceous glands and the sweat glands
...
They produce an oily substance called
the sebum
...
The mammary glands are the modified sweat glands
...
3
...
4
...
They are simple coiled tubular glands
...
The gland has two parts
...
The number of
sweat glands are more in the palms of the hands and soles of the feet
...
They are the nail root and the nail
body
...
The nail root is covered by the skin
...

free edge
nail body

hyponchium

nail bed

nail groove
nail fold

nail root

lunula
eponchium
nail root
dorsal view

longitudinal section
Fig
...
1
...
Nail

89

The stratum corneum of the nail fold grows onto the nail body as the
eponchium
...
The nail is
found placed on the nail matrix and nail bed
...
It contains the nail matrix
...
5-1
...


3
...
Skeletal system
The skeletal system is constituted by bones, cartilages and ligaments
...
Further, bones remain as regions for the attachment of muscles
...
Structures
like skull, protect inner organs
...
The
bones remain as reservoirs of fat and certain minerals
...

skull
mandible
clavicle
scapula
sternum
ribs

humerus

vertebral column

ulna
coxa
radius

sacrum

carpals
metacarpals
phalanges
femur
patella
tibia
fibula
tarsals
metatarsals
phalanges
Fig
...
2
...
The complete skeleton

90

The bones can be long, short, flat or irregular in shape
...
Short bones are broad in shape
...
Flat bones are thin and flattened
...
Verterbral
and facial bones are irregular in shape
...

The outer layer of the periosteum is fibrous in nature
...

A growing long bone has three regions
...
It is made up of compact bone
...
3
...
2
...
It is made up of spongy
bone
...
In between
the epiphysis and diaphysis epiphyseal or growth plate is found
...
Growth in length of bone occurs at this plate
...
This
cavity is lined by a membrane called the endosteum
...
It is mostly adipose tissue
...

91

Dried, prepared bones are used to study skeletal anatomy
...
The named bones are divided into two categories: (1) the axial skeleton and (2) the appendicular
skeleton
...
The appendicular skeleton consists of the limbs and
their girdles
...
Among the bones of the axial
skeleton 28 bones are in the skull, 26 bones in the vertebral column, 25
bones in the thoracic cage and one remains as the hyoid bone
...
It protects the brain,
the spinal cord and the vital organs found within the thorax
...
It consists of 22
bones
...
It supports the organs of vision, hearing, smell
and taste
...

The skull or cranium is covered by eight bones
...
These bones are joined by sutures to form a compact box like structure
...

frontal bone
parietal bone
eye orbit
sphenoid bone
nasal bone
temporal bone
zygomatic bone
maxilla

mandible
Fig
...
2
...
Skull

92

suture
frontal bone
parietal bone
sphenoid bone
nasal bone
occipital bone
zygomatic bone
temporal bone
maxilla

mandible
Fig
...
2
...
Skull - Lateral view

In the front there are 14 facial bones
...

Mandible or lower jaw and vomer are unpaired bones
...
The parietal bones are joined to the occipital bone at the
back
...

The large hole in the temporal bone is the external auditory meatus
...
On the
lateral side immediately anterior to the temporal, the sphenoid bone is seen
...
It is a
prominent bone on the face
...
The
mandible constitutes the lower jaw
...
The most prominent openings in the skull are the orbits and the nasal cavity
...
The bones of the orbits provide protection for
the eyes and attachment points for the muscles that move the eyes
...
The head region also contains 6 ear ossicles
...

93

A large opening found at the base of the skull is the foramen
magnum
...

b)
...
The vertebral column consists of 26 bones
...
They are the cervical (7), thoracic (12), lumbar (5),
sacral (1) and coccygeal (1) vertebrae
...
3
...
5
...
The centra of adjacent vertebrae are
separated by intervertebral discs of cartilage
...
It encloses the neural canal
...
Several bony projections are seen on the vertebral arch
...
On the dorsal
side there is a neural spine
...
Further, there are two superior and two inferior processes meant
for articulation with the neighbouring vertebra
...
3
...
6
...
It balances and supports the
head
...
The second is the axis
...
They form a triangular structure called the sacrum
...
It is a vestige
...
Of these, 5 sacral bones are
fused to form a single sacral bone
...


sacrum

coccyx
Fig
...
2
...
Sacrum and coccyx

95

c)
...
Each articulates with a thoracic
vertebra
...
The first seven are attached directly to the sternum
...
Cartilages of 8th, 9th and 10th ribs are
fused and attached to 7th
...
11th 12th pairs are
not attached to the sternum
...

1st thoracic vertebra

clavicle

scapula
sternum

humerus

xiphoid process

costal cartilage
th

12 thoracic vertebra

Fig
...
2
...
Rib cage

Appendicular skeleton
It consists of the bones of the upper and lower limbs and the girdles
by which they are attached to the body
...
Both of them
are attached loosely by muscles to the body
...
Hence it is possible to place the hand in a wide range of
positions
...
3
...
9
...
Each
pair has a scapula or shoulder blade and a clavicle or collarbone
...
A glenoid fossa is located in the superior lateral
region of the scapula
...
The clavicle
is a long bone
...
It can be easily seen and felt
...

clavicle
scapula
humerus

ulna
carpals

radius

metacarpals
phalanges
Fig
...
2
...
Skeleton of the arm

Pelvic girdle or pelvis - It is a ring of bones formed by the sacrum and
paired bones called the coxae or hip bones
...
3
...
11
...
A fossa called the acetabulum is located on the lateral
surface of each coxa
...

pelvis

femur

patella
tibia
fibula
tarsals
metatarsals
phalanges
Fig
...
2
...
Skeleton of the leg wih pelvic girdle

Upper limb or hand - The part of the upper limb from shoulder to the elbow
is the arm
...
The head of humerus articulates with the glenoid fossa of the scapula
...


Fig
...
2
...
Femur

Forearm - This part of the hand is in between the arm and the wrist
...
They are the ulna and the radius
...

98

Wrist - This short region is composed of eight carpal bones
...
The carpals along with accompanying
ligaments are arranged in such a way that a tunnel on the anterior surface of
the wrist called the carpal tunnel has been formed
...

Hand - The bony framework of the hand is formed of five metacarpals
...
The concave nature of the palm
in the resting position is due to curved arrangement of metacarpals
...
3
...
14
...
They include one thumb and four fingers
...
While the thumb has two
phalanges other fingers have three each
...


bone
fibrous capsule
articular cartilage

synovial fluid

Fig
...
2
...
A Synovial joint

99

The upper region of the leg is the thigh
...
It has a prominent rounded head for articulating with
the acetabulum of the pelvic girdle
...

The knee region has a large, flat bone called the patella
...


Leg - The leg is that part of the lower limb between the knee and the ankle
...
The tibia is larger and
it supports most of the weight of the leg
...
The ankle articulates with
the tibia and the fibula through the talus
...
They correspond to the
metacarpals and phalanges of the hand
...
Our skeletal muscles
are firmly attached to bones
...
Hence movements need movable bone joints
...

All joints are not movable
...

The joints are named according to the bones that are united
...
They are the fibrous,
cartilaginous and synovial joints
...
There is no joint cavity
...
Sutures
formed between cranial bones, a syndesmosis (to bind) between radius and
ulna are examples for this type
...
The articulation between the first rib and the sternum is an example for syncondrosis
...


Synovial joints - These joints contain a synovial fluid
...
It forms a thin lubricating film covering the surfaces of a joint
...

100

3
...
Muscular System
Locomotion and bodily movements are characteristic features of the
animals
...
Muscular movements are more powerful and
energetic
...
The inner smooth muscles of the visceral
organs make them work like machines all through the life period
...
Thus the highly specialized muscle tissues are responsible for the mechanical processes in the
body
...
They are the skeletal, visceral and
cardiac muscles
...
Skeletal muscles or striped muscles : These muscles are attached to
the bones
...
These voluntary muscles
cause body movements
...
Visceral muscles or Nonstriated muscles: These are found in the walls
of the inner organs such as blood vessels, stomach and intestine
...
These are involuntary in nature
...
Cardiac muscle : These are found in the wall of the heart
...
The muscles are involuntary in nature
...

The skeletal muscles are attached to bones by tendons
...
These
muscles are covered by sheets of connective tissue called fascia
...

They are like cords or straps strongly attached to bones
...
A tendon having 10 mm diameter can
support 600 - 1000 kg
...
The fascia may be superficial or deep
...

The deep fascia are collagen fibres found as a tough inelastic sheath around
the musculature
...

101

Shapes of muscles
...
Based on
general shape and the orientation or muscle fibres in relation to the direction
of pull, they can be grouped into two classes
...
Parallel : These muscle fibres are parallel to the line of pull
...
The individual fibres run
the entire length of the muscle
...
Oblique : These muscle fibres are oblique to the line of pull
...
The pennate forms may be
unipennate, bipennate, multipennate or circumpennate
...


Naming of muscles
...

Shape
deltoid

Size
-

triangular

major

- large

quadratus -

square

minor

- small

gracilis

slender

longus - long

-

lattismus - broadest
Number of Heads

Position

biceps - 2 heads

dorsi - of the back

triceps - 3 heads

pectoralis - of the chest

quandriceps - 4 heads

brachii - of the arm
anterior, posterior
...
Muscles of the head
There are two groups of muscles
...
The craniofacial muscles are related to eye orbital margins,
eyelids, nose, nostrils, lips, cheeks, mouth, pinna, and the scalp
...
Among these muscles those
that are related to the lip movement are significant
...
Such thought related
movements are caused by several muscles associated with lips and the skin
around the mouth
...
Smiling is accomplished by zygomasticus major and minor, levator anguli oris
and risorius
...
The chin dimples are located between the mentalis
muscles
aponeurosis
auricular muscles
pars frontalis
orbicularis oculi

pars occipitalis
zygomaticus muscles

levator labii

masseter
sternocleidomastoid

orbicularis oris
mentalis

platysma

Fig
...
3
...
Muscles of the Head

The masticatory (or speech) muscles move the mandible of the
lower jaw
...
Tongue movements are caused by intrinsic and
extrinsic muscles
...


II
...

The movements of the neck region are caused by cervical, suprahyoid, infrahyoid and vertebral muscles
...
Muscles of the Trunk region
...

These are strong back muscles that help the trunk to maintain erect posture
...

Four important thoracic muscle groups are associated with the process of breathing
...
Major breathing movement is due to
diaphragm, a curved musculofibrous sheet that separates thoracic and abdominal cavities
...

The inferior opening of the pelvic bone is covered by pelvic diaphragm muscles
...
The perineum
and other “subfloor” muscles form the urogenital diaphragm
...
However by specific exercises they can be strengthened
...
3
...
2
...
Muscles of the upper limb
...

The trapezius is a flat, triangular muscle
...
It maintains the level and poise of the shoulder
...
It helps to bend the neck backwards and laterally
...
It is a conspicuous muscle stretching over the lumbar region and lower thorax
...
It helps in
the backward swinging of the arm
...
It is useful in violent expiratory activities such as coughing or sneezing
...

Serratus anterior and pectoralis major connect the ribs to the
scapula
...
It is a fan shaped muscle
...
It helps to swing the extended
rectus
arm forward and medially
...
It is active in deep inspiration
...
The coracobrachialis arises from the coracoid bone
in the shoulder and ends in the humerus of the upper arm
...
The biceps brachii is a large fusiform muscle
...
They are connected to the coracoid
and shoulder joint
...
It is a
powerful muscle causing flexing of the hand
...
The
wrist, hand and finger movements are caused by several extrinsic and intrinsic hand muscles
...


V
...

Thigh movements are caused by anterior, postereolateral and deep
muscles
...
The gluteus maximus form the mass of the buttocks region
...
The sartorius is the longest muscle of the body
...
Muscle movement of ankle foot and toe are caused by
several groups of extrinsic and intrinsic muscles
...

105

3
...
Digestive system
The process of nutrition in man is holozoic
...
In
digestion, the macromolecules or biopolymers of food are hydrolysed to yield
their corresponding monomers
...
Thus
the digestive system comprises the alimentary canal, associated glands and
regions of absorption of food
...


oral cavity (mouth)

pharynx

oesophagus
liver
gall bladder

stomach
pancreas

small intestine

large intestine

appendix

anus

Fig
...
4
...
Digestive system

Mouth or Buccal cavity
The opening of the oral cavity is bounded by the lips
...
The lateral walls of the oral
cavity are the cheeks
...
The lips and cheeks are useful in the process of
mastication and speech
...
It is attached to the floor of the oral
cavity
...
A thin fold of tissue called the
frenulum attaches the free end to the floor of the mouth
...
About two thirds
of the anterior surface is covered by papillae
...

Teeth - There are 32 teeth in the mouth of a human adult
...
There are 4 different types of permanent teeth seen
...
The types of teeth are incisors(8), canines(4), premolars(8) and molars(12)
...

i

2/2

:

c

1/1

:

pm

2/2

m

3/3

X

2

or

incisor
canine
I premolar
II premolar
I molar

upper jaw

× II molar

III molar

lower jaw

Fig
...
4
...
Dentition

Each tooth consists of three regions
...
The crown region has one or more cusps
...

The dentine of the tooth crown is covered by an extremely hard substance called enamel
...
It helps to anchor the tooth in the jaw
...
This cavity is also called as
the root canal
...
The canal opens
at the base through apical foramen
...
This region of the jaw is covered by dense fibrous connective tissue and
stratified squamous epithelium
...

enamel
crown
dentine
neck
pulp cavity with nerve and
blood vessels
root

cementum
root canal
apical foramen

Fig
...
4
...
A tooth

Salivary glands : These are scattered throughout the oral cavity
...
They are the parotid, submandibular and sublingual
glands
...
They are located just anterior to

parotid duct

parotid gland

sublingual gland

submandibular gland

Fig
...
4
...
Salivary glands

the ear on each side of the head
...
The sublingual glands are the smallest
...

There are other numerous small, coiled, tubular glands in the mouth
...

108

Pharynx : A description of pharynx is provided under respiratory system
...
It is about 25 cm long
...
It passes through
the diaphragm and ends at the stomach
...
The
inner wall is lined by a moist stratified squamous epithelium
...


Stomach : It is an enlarged sac like structure
...
It is divisible into two regions namely
cardiac and pyloric stomachs
...
The oesophagus opens into the cardiac stomach through the gastroesophageal or cardiac opening
...
The largest part of the stomach is the body
...
The pyloric opening between the
pylorus and intestine is surrounded by a ring of muscles called the pyloric
sphincter
...
3
...
5
...
The entire small intestine is about 6m
...


Duodenum - It is about 25 cm
...
It curves within the abdominal cavity
and completes nearly 180 degree arc
...

Jejunum and ileum- The jejunum and ileum are 2
...
and 3
...
These two are similar in structure to the duodenum
...
The junction
between the ileum and the large intestine is the ileocaecal junction
...


Liver : It is the largest visceral organ
...
36 Kg
...
The bile secreted by the liver gets collected in the gall bladder
...
The common hepatic duct is joined by the cystic duct from the gall bladder to form the
common bile duct
...

Gall bladder : It is a sac like structure on the inferior surface of the liver
...


liver
gall bladder

pancreas
common bile duct
hepatopancreatic
ampulla

pancreatic duct

duodenum
Fig
...
4
...
Duodenal region

Pancreas : It is a compelx organ
...
The endocrine part of the pancreas consists of pancreatic islets
...
The exocrine part of the pancreas
consists of acini
...
The pancreas consists of
several lobules
...
It joins the common bile duct at the hepatopancreatic ampulla
...

Caecum : It is the proximal end of the large intestine
...
The caecum is about 6 cm in length
...
It is called the vermiform
appendix
...
5 - 1
...
It consists of four parts namely the
ascending colon, transverse colon, descending colon and sigmoid colon
...

Rectum : It is a straight, muscular tube that extends from the sigmoid colon to
the anal canal
...
It ends at the anus
...


3
...
These processes are facilitated by working together of well developed
respiratory organs and the circulatory system
...
These organs are organised into upper and lower
respiratory tracts
...

nasal cavity
external nose

uvula
nasopharnyx
oropharynx
laryngopharynx
epiglottis
oesophagus

trachea

Fig
...
5
...
Upper Respiratory tract

1
...
The nose is a
visible prominent structure
...
The
bridge of the nose is formed of the nasal bones and extension of the skull
111

bones(frontal and maxillary)
...
The nasal passage opens to the outside through
external nostrils
...


2
...

It is a common pathway that opens into the oesophagus of the alimentary
canal and larynx of the respiratory system
...

The nasopharynx extends from the internal nostril to the region of
the uvula
...
It prevents the entry of food into the nasal
cavity
...

The middle ear opens into the nasopharynx through two auditory tubes
...
The inner surface of the nasopharynx also contains the
pharyngeal tonsil or adenoid meant for defence against infections
...

The oropharynx remains between the uvula and the epiglottis
...
Near the opening of the oral cavity 2
sets of palatine tonsils and lingual tonsils are present
...


3
...

This region is surrounded by cartilages(3 unpaired and 6 paired)
...

The unpaired cartilages are the thyroid, cricoid and epiglottis
...
It is also known as the Adam’s apple
...
3
...
2
...
The other cartilages are
placed above the cricoid
...
It projects
as a free flap over the opening of the larynx
...

The ligaments inside the larynx form the vocal folds or vocal cords
...
The
vocal cords are involved with sound production
...
Louder sounds are made by increasing the amplitude of vibrations
...
The length is altered by
muscles attached to the cartilage
...
The sound made by the vocal cords can be altered by the tongue, lips
and teeth to form words
...
Trachea (or wind pipe) : It is a membranous tube
...
The wall is provided support by 15-20
‘C’ shaped cartilage rings
...

The inner wall of the trachea is lined by mucous membrane
...
The cilia of this epithelium help to propel
mucus and foreign particles towards the larynx
...
Its inner diameter is 12 mm
...

The basal part of the trachea divides to form 2 smaller tubes called the primary bronchi (sing : bronchus)
...
Foreign objects reaching carina stimulate a powerful cough
reflex
...
Lungs : The pair of lungs are the actual organs of respiration
...
The base of the lung rests on the diaphragm
...
The left lung weighs 560g
...

The lungs are placed within the thoracic cavity
...
The region inside the pleural membrane is named as the pleural cavity
...


113

Larynx
trachea
carina
pleura

primary bronchus
secondary bronchi

branchioles

Fig
...
5
...
Lungs

The region in between the two lungs is named as the mediastinum
...

Structures such as the primary bronchi, blood vessels, nerves and
lympatic vessels enter or exit the lungs at a specific region on the inner margin
of the lungs
...
All structures passing through
the hilum are referred to as the root of the lung
...
There are two secondary bronchi in the left lung and
three in the right lung
...

They divide still further and finally give rise to bronchioles
...
These bronchioles divide several times to
become still smaller terminal bronchioles
...
shaped
cartilages and smooth muscles
...

The terminal branchioles end in small air filled chambers called alveoli
...
They collectivelly provide the respiratory surface for gaseous exchange
...
The
thickness of the wall of the alveolus is as little as 0
...
Studies have shown
that in human lungs there are about 300 million alveoli
...


114

5
...

Eventhough the lungs are the principal organs of respiration, the process
of ventilation happens by an indirect method
...
Thoracic modifications during respiration happen
due to several muscles
...
These muscles are the diaphragm, external and internal
intercostal muscles between the ribs, pectorals and scalene (Ref
...


3
...
The Circulatory System
The multicellular organisation in animal world has resulted in the origin
and evolution of circulatary system in animals
...
Among
majority of multicellular animals this system remains as a closed type
...
In
man, as in all mammals there is a double circulation of blood
...
The blood later returns to the heart
...
A similar circulation carries blood
to lungs for oxygenation and returns it back to the heart
...

tissue capillaries
lung capillary
left side of heart

right side of heart

arteries

veins
tissue capillaries
Fig
...
6
...
Systemic and Pulmonary circulations

115

Systemic and Pulmonary circulations
The most important component of this system is the heart
...
The chambers are
the right atrium, left atrium, right ventricle and left ventricle
...
The right and left chambers are separated
by septa
...
When the atria contract, blood from the
left atrium is forced into the left ventricle
...
The aorta is the single
systemic artery emerging from the heart
...
3
...
2 Human - Arterial system

116

internal jugular vein
external jugular vein
L
...
subclavian vein

brachial vein
radial vein
ulnar vein

femoral vein
anterior tibial vein

Fig
...
6
...
Human - Venous system

gives rise to hundreds of arteries taking blood to all regions of the body
...
In
the target organs they produce four times as many capillaries
...

Finally, only two veins, the superior and inferior vena cavae return the blood

to the right atrium
...

Pulmonary circulation :- The venous blood from right atrium is conducted to
the right ventricle
...
The oxygenated blood later returns by the pulmonary veins to the
left atrium
...

117

Portal circulation :- In the systemic circulation the venous blood passing
through spleen, pancreas, stomach and interstine is not carried back directly
to the heart
...
This vein
begins as capilaries from the visceral organs and ends in the liver again as
capillaries
...
This route is the portal
circulation
...

The Veins carry blood towards the heart
...
They can also be classified
according to their size and wall structure
...


1
...
the walls of these vessels are elastic in nature
...
Distributing vessels :- These are smaller arteries reaching individual
organs
...
They have muscular walls
...
Resistance vessels :- These are mostly arterioles
...
Hence these vessels can reduce
pressure of blood due to peripheral resistance
...
Exchange vessels :- These are the capillaries
...
The
substances commonly exchanged are oxygen, carbon-di-oxide, nutrients, water,
inorganic ions, vitamins, hormones, metabolic products and antibodies
...
Capacitance or reservoir vessels :- These are the larger vessels and
veins
...
They collect and convey blood back to the
heart
...

Hence their blood content is more, even at low pressure
...
Thus the veins are called as the “blood reservoirs”

Structure of blood vessels
The blood vessels show a vast range of structural modifications
...

A blood vessel consists of a wall and a lumen or cavity
...
They are the
tunica intima, tunica media and tunica externa or tunica adventitia
...
3
...
5
...
The tunica media contains smooth muscle cells
...
The tunica externa is composed
of connective tissue
...


Types of blood vessels
1
...
The smooth wall measures about 1micron in thickness
...

119

2
...
The
larger muscular arteries are inelastic and they have thick walls
...
Since they regulate
blood supply, they are called distributing arteries
...

3
...

These are small vessels capable of vasodilation and vasoconstriction
...
Capillaries :- These are fine vessels found between arterioles and venules
...

capillary endothelial cell
nucleus

Fig
...
6
...
A Capillary tube

5
...

Each venule is formed by the convergence of two or more capillaries
...


6
...
They run in between
venules and large veins
...

Veins with diameter above 2 mm have valves
...
They allow movement of blood towards the heart
...


Branching of blood vessels :- When an artery divides into two equal branches,
the original artery ceases to exist
...
The smaller branching vessels formed on the sides are called the
collateral branches
...

Blood supply to blood vessels :- As any other region, the cells and tissue
on the wall of the blood vessel require nourishment
...
For vessels having diameter greater than 1 mm, diffusion of nutrients may not be possible
...
They penetrate into the wall of
the blood vessels
...
They regulate the contraction of the musculature
...


The Heart
The heart is a hollow, fibromuscular organ
...
It is roughly the size of a closed fist
...
Transverse diameter at its broadest
region is 8-9 cm
...
While in adult male the
heart weighs 280-340 g, in female it weighs 230-280 g
...
3
...
7
...
The heart lies obliquely in the mediastinum
...
The outer layer is called the fibrous pericardium
...
In between heart and pericardium,
there is a pericardial space
...

aorta
pulmonary artery

superior vena cava

tricuspid valve
inferior vena cava

left atrium
pulmonary veins
semilunar valves
bicuspid valve
chordae tendineae

right ventricle

inter ventricular septum
left ventricle

right atrium

Fig
...
6
...
Internal structure of the Heart

121

The wall of the heart is made up of three tissue layers
...
The epicardium forms the
smooth outer surface of the heart
...
This layer plays an important role in the functioning of the
heart
...
It is formed of
squamous epithelium
...
7
...
It helps to maintain fluid
balance in tissues and it absorbs fat from the digestive tract
...
This system includes lymph, lymphocytes, lymphatic vessels, lymph
nodules, lymph nodes, tonsils, the spleen and the thymus gland
...

These tissues primarily consist of lymphocytes
...
Lymphocytes are a type of white
blood cells
...
There are several classes of lymphocytes
...
T- lymphocytes can recognize and selectively kill cells infected with viruses
...
The T lymphocytes get
matured only after entering into Thymus, a lymphoid organ through circulation
...
Thus the thymus and bone marrow are described as central or primary
lymphoid organs
...
It is located in the mediastinum (ie
...
It lies between the sternum and the pericardium
...
It is largest in the early part of life (upto 15 years)
...
After puberty it greatly decreases in size
...
It has 2 layers
...
The lymphocytes are found only in cortex layer
...
Their size ranges from 125 mm
...

These nodes are found all over the body
...
These are the inguinal nodes in the
groin, the axillary nodes in the axillary region and the cervical nodes of the
neck
...
The nodes contain open spaces called sinuses
...


Spleen - It is roughly the size of a clenched fist
...
It has a fibrous capsule
...


Tonsils - These are the largest lymph nodules
...
In adults the tonsils decrease in size and
may disappear
...
Of the
three, the palatine tonsils are usually refered to as “the tonsils”
...
The pharyngeal tonsil or adenoid are found near the junction between the nasal cavity and the pharynx
...


subclavian vein

thoracic duct

lymph nodes

lymphatic vessel
Fig
...
7
...
Lymphatic system

The lymphatic circulation - The lymph fluid from the tissues is drained by
lymphatic capillaries
...
The lymphatic capillaries join into larger vessels
...
These vessels and associated lymph
nodes are arranged in regional groups
...

Nodes within a group are interconnected
...

The regional vessels return to the venous blood circulation via the
right and left lympho venous portals
...
8
...
Several billion cells remain associated with this system
...
Hence, scientists from different fields collectively
are interested in understanding the functioning of this system
...
Even to-day thousands
of scientists are involved in researches for knowing the structure and functioning of the brain
...

Basically the nervous system is formed of nerve cells or neurons
...
They also help in realising,
analysing and storing messages
...
The
network of interconnected neurons in the nerves, brain and spinal cord have
highly complicated methods of functioning
...
The projections
of the cyton are the dendrites and the dendrons
...
There are variations in the shape of the cyton,
number of dendrons and nature of axon
...
Such specialized connections are called
as synapses
...
These joints are named as
neuro - muscular junctions
...
A nerve fibre contains
axons with their coverings called schwann cells
...
The number and pattern of fasciculi vary in different nerves
...
Such a trunk is surrounded by an
epineuruium
...
The perineurium surrounds the endoneurium or intra fascicular connective tissue
...
The thickness is more when there
are more fasciculi
...

The perineurium contains alternating layers of flattened polygonal cells
...
The components of the
endoneurium remain bathed in endoneurial fluid
...
These
minute blood vessels radiate upto the endoneurium
...
However,
for study purposes it can be divided into systems and organs
...
Central nervous system (C N S)
This system includes the brain and the spinal cord or medulla spinalis
...
While the brain is located within
the cranium, the spinal cord is placed within the vertebral canal of the vertebrae
...


B
...

It consists of nerves and ganglia
...
There are 12 pairs of cranial nerves and
31 pairs of spinal nerves
...
Autonomous nervous system
...
It is also called the involuntary nervous system
...

125

1
...
Inside the skull the
brain is surrounded by three protective coverings
...

1
...

2
...

The duramater is the outermost membrane
...
The arachnoid mater is the middle covering over the brain
...
It
contains cerebro-spinal fluid and blood vessels
...
This membrane contains blood capillaries supplying blood to the brain cells
...
3
...
1 L
...
of the human brain

The human brain weighs about 1
...
It contains more than a billion
neurons
...


1
...
The cerebrum is the largest part of the brain
...
However, at the base the
two hemispheres are connected by a sheet of nerve fibres called the corpus
callossum
...

It is 2 to 4 mm thick
...

The surface of the cerebrum has several folds called the gyri
...
The shallow grooves in between the
gyri are called the sulci
...

Each cerebral hemisphere is divided into four lobes
...

The diencephalon contains the thalamus and hypothalamus
...

The thalamus has a cluster of nuclei which act as the relays for particular sensory pathways
...
It contains reflex centres linked to the autonomic system
...
It is connected to
the neurohypophysis of the pituitary gland
...
Mesencephalon (mid brain) - It is the smallest region of the brainstem
...

3
...

The cerebellum consists of two hemispheres
...
The cerebellum consists of three parts
...

The pons is just superior to the medulla oblongata
...

The medulla oblongata is about 3 cm long
...
It remains as a bridge between the brain and the spinal cord
...

It connects the spinal cord to the brain
...

Spinal cord - The spinal cord extends from the foramen magnum to the level
of the second lumbar vertebra
...
There are two enlargements in the spinal cord
...
Below the lumbar enlargement the spinal cord tapers
to form a cone like region called the conus medullaris
...
The conus medullaris and the nerves extending below resemble
a horse’s tail
...

A cross section of the spinal cord reveals a central grey portion and a
peripheral white portion
...

dorsal root

dorsal ganglion
dorsal fissure
grey mater
central canal
white mater
ventral fissure
ventral root

Fig
...
8
...
Cross section of the spinal cord

The dorsal and ventral sides have long fissures
...
Each nerve has a dorsal root and a
ventral root from the spinal cord
...


Ventricles
The entire CNS remains as a hollow tube
...

Each cerebral hemisphere contains a large cavity called the lateral
ventricle
...
The
two lateral ventricles communicate with the third ventricle located in the
centre of the diencephalon
...
The third ventricle inturn
opens into the fourth ventricle found inside the medulla oblongata
...
The fourth ventricle is continuous with the
central canal of the spinal cord
...


Cerebro-spinal fluid (CSF)
This fluid fills the ventricles of the brain and the central canal of the
spinal cord
...
Remaining 10-12 % is produced by similar cells in the 3rd and 4th ventricles
...
The plexuses are formed by invagination of the vascular piamater
into the ventricles
...
9
...

Living organism respond to several stimuli such as light, heat, sound,
chemicals, pressure, touch, stretch and orientation
...
The receptors convert the stimuli into impulses in the nervous systems
...
Such
receptors are single nerve cells responding directly to the stimulus
...
On these organs the stimulus is channelled into a receptive region of the organ
...


The eye
The eye is formed of 3 coats or tunics
...
Outer or fibrous

- sclera & cornea

2
...
inner or nervous

- retina

choroid
ciliary body

sclera

cornea
pupil
iris

retina

lens
Optic Nerve
Fig
...
9
...
C
...
of human eye

129

The sclera is the white outer layer of the eye
...
This firm layer provides shape and protects the internal
structures
...

In the front, the outer layer forms a transparent region called the cornea
...
The cornea is made up of a connective tissue
having collagen, elastic fibres and proteoglycans
...
It contains most
of the blood vessels
...
It appears black in colour
...
Anteriorly this layer forms
the ciliary body and iris
...
Contraction of the ciliary muscles can change the shape of the lens
...
3
...
2
...
It may be black, brown or
blue
...

Light enters the eye through the pupil
...

The inner most tunic of the eye is the retina
...
The sensory retina is light
sensitive
...


130

Compartments of the eye : The eye has 2 major compartments
...
Behind the lens there is a larger
compartment
...
3
...
3
...
There is
an anterior chamber found between the cornea and iris
...
These two chambers are
filled with a substance called the aqueous humor
...

The posterior compartment of the eye is much larger and it
contains a transparent jellylike substance called vitreous humor
...
It is transparent and
biconvex
...

These fibres have an accumulation of proteins called crystallines
...

The functioning of the eye is aided by accessory structures
...

The eyebrows prevent the sweat during perspiration from running
down into the eye
...

The eyelids and associated lashes protect the eyes from foreign objects
...
It contains modified sebaceous and sweat glands
...
Modified
sweat glands called the ciliary glands open into the follicles of the
eyelashes
...
The inner margin of the eyelids contain
Melbomian glands
...

The inner surface of the eyelids and the anterior surfae of the eye are
covered by a thin, transparent mucous membrane called the conjunctiva
...
They produce tear at the rate of about 1 ml / day
...
At the
corners of the eye there are small openings called the puncta
...
The lacrimal canaliculi open into a
lacrimal sac
...
These ducts help to drain the excess tear
...


Ears (The organs of hearing)
The ears are the organs of hearing and balance
...


External ear - The fleshy part outside the head is called the pinna
...
It is followed by the external auditory
meatus
...
These
glands produce cerumen or earwax
...
The ear drum or tympanic membrane is
a oval, three layered structure
...

external auditory meatus
semi circular canals

pinna

auditory nerve
cochlea

stapes
incus
malleus

tympanic membrane

ear ossicles

Fig
...
9
...
Ear - Inner structure

Middle ear - It is an air filled cavity
...
The handle of malleus is in contact with the
inner surface of the ear drum
...
While the stapes on one side is attached to the incus, its other side fits
into the oval window
...


Inner ear - This region has tunnels and chambers inside the temporal bone
132

called the bony labyrinth
...
The oval window found in
between the middle and inner ears communicates with the vestibule of the
inner ear
...


3
...
They are the nervous
and endocrine systems
...
The endocrine system sends
information to the tissues it controls in the form of chemical signals
...
They
are carried to all parts of the body
...
The hormones of the endocrine glands
regulate and control the functioning of several organs in the body
...
There are several endocrine
glands in our body
...


pituitary
thyroid

parathyroids

adrenal

pancreas
ovaries

testes
Fig
...
10
...
The Major Endocrine glands

An understanding of the structure and form of each endocrine gland,
its secretory products and the means by which its activity is regulated is absolutely essential
...

133

Pituitary gland (or) Hypophysis
It is an organ, that secretes eight major hormones
...
The hypothalamus of the brain is connected to
the pituitary
...


Structure of the pituitary gland
...
It weighs 0
...
It is
placed in a region called the sella turcica of the sphenoid bone in the floor of
the skull
...
It is connected to it by a
stalk of tissue called the infundibulum
...

They are the posterior pituitary or neurohypophysis and anterior pituitary or adenohypophysis
...
pituitary)
neurohypophysis
(post pituitary)

pars distalis
(b)

(a)

pars intermedia

Fig
...
10
...
(a) Entire (b) L
...
of the pituitary gland

Posterior pituitary or Neurohypophysis
...
Hence it is called
the neurohypophysis
...

The outgrowth of the brain, forms the infundibulum
...
Since this part of the
pituitary is an extension of the nervous system, its secretions are known as
neurohormones
...
It is called as the Rathke’s pouch
...
Later, the pouch loses its connection with the
oral cavity and becomes the anterior pituitary
...
They are, the pars tuberalis, pars distalis and pars
intermedia
...

There is a network of blood vessels on the hypothalamus
...
A portal system called the
hypothalamohypophyseal portal system extends from a part of the hypothalamus to the anterior pituitary (a portal blood vessel begins and ends as
capillaries)
...
The neurohormones produced by the hypothalamus are collected by the primary capillary network
...


Thyroid gland
The thyroid gland is composed of two lobes
...
These lobes are connected by
a narrow band of thyroid tissue called the isthmus
...


trachea
thyroid

glandular cells
acinus

parathyroid

Fig
...
10
...
Thyroid C
...
3
...
3
...
It weighs approximately 20g
...
It is more red than its
neighbouring tissues
...
They are small spheres
...
The central cavity or
lumen of each follicle is filled with a protein called the thyroglobulin
...
The thyroid secretes thyroxine and calcitonin
...

The parathyroid glands are found in association with the thyroid glands
...
There are four parathyroid glands
...
The cells of the glands secrete parathyroid hormone
...

These glands are found near the superior pole of each kidney
...
The glands are enclosed by a connective
tissue capsule
...
These regions are formed from two separate embryonic tissues
...
They are centrally located in the gland
...
These cells form
three distinct layers, namely the zona glomerulosa, the zona fasciculata
and the zona reticularis
...

The adrenal medulla secretes two major hormones
...
The hormones
of the adrenal cortex are the cortisol and aldosterone
...

The pancreas lies between the greater curvature of the stomach and
the duodenum
...
It is approximately 15 cm long
...

The pancreas is both an exocrine and an endocrine gland
...
They are
approximalety 500,000 to 1,000,000 in number
...
The islets are composed of alpha (α) cells (20%) and beta (β )cells
(75%)
...
A
third type of cells called the delta ( δ ) cells (5%) have been identified
...


3
...
The suitability of this concept is questionable
...
In postnatal human beings, the association between the components of the urinary and the reproductive systems is very much limited
...

The urinary organs comprise, two kidneys (renes), ureters, the urinary bladder (vesica urinaria) and the urethra
...
3
...
1
...

The kidneys are bean shaped organs
...
They lie on the posterior abdominal wall
...
It is because of the
presence of liver superior to it
...

Each kidney is about 11 cm in length, 6cm in breadth and 3cm in anteroposterior dimensions
...

cortex
renal hilum
renal artery
renel vein
renal pelvis

renal pyramids

calyx
medulla
ureter
Fig
...
11
...
L
...
of Kidney

137

The inner margin of each kidney has a small depression called the
hilum
...
The hilum opens into a cavity called the renal sinus
...
Internally the kidney is divided into an outer cortex and an
inner medulla
...
Extensions of the pyramids called the medullary rays, project
from the pyramids into the cortex
...
The tips of the pyramids are called the
renal papillae
...
The renal papillae
are surrounded by funnel shaped structures called the minor calyces
...
There are 8-20 minor calyces and 2 or 3 major calyces per
kidney
...
The renal pelvis then narrows to form the ureter
...


Nephron
...
There are
approximately 1
...
Atleast 450,000 of them
must remain functional to ensure survival
...
The distal tubule opens into a collecting duct
...

The collecting tubules and parts of the loops of Henle enter the renal medulla
...
3
...
3
...
15% of the nephrons
are larger and they remain near the medulla
...
They have larger loops of Henle
...

In the Bowman’s capsule the outer and inner layers are called parietal and visceral layers respectively
...
The inner visceral layer surrounds the glomerulus
...
The walls of the glomerular capillaries are lined with endothelial cells
...
The capillary endothelium, the basement
membrane and the podocytes of Bowman’s capsule make up the filtration
membrane
...
It is
drained by an efferent arteriole
...
The
proximal tubule is also called the proximal convoluted tubule
...

Posteriorly the proximal tubule continues as the loop of Henle
...
The first part of the descending limb is similar in structure to the proximal tubule
...
The
first part of the ascending limb is also very thin and it consists of simple squamous epithelium, but it soon becoms thick
...


Ureters and Urinary bladder
The ureters extend inferiorly from the renal pelvis
...
The bladder is meant for
temporarily storing the urine
...
It
lies in the pelvic cavity
...
The bladder capacity varies from 120-320ml
...
Micturition will occur at 280ml
...
The urethra exits the bladder
inferiorly and anteriorly
...
Around
the urethra there is another external urinary sphincter
...

In the male the urethra extends to the end of the penis where it opens
to the outside
...
In the female the urethra
is shorter
...


3
...
Reproductive system
The process of sexual reproduction is a wonderful act in nature
...
Organisms have
adopted several strategies for sexual reproductive processes
...
Human reproductive organs as internal and external genitalia are highly sophisticated yet simple in their functioning
...
An
academic approach towards an understanding of the human male and
female reproductive organs and their functions will go a long way in
avoidance of unethical, unhealthy and unhygenic practices encountered at specific periods in life
...


ureter
urinary bladder
prostate gland
urethra

vas deferens
seminal vesicle

epididymis

anus

penis
testis

scrotum

Fig
...
12
...
Human male reproductive organs

140

Testes : The testes are the primary reproductive organs or gonads in the
male
...

The sperm cells are temperature sensitive
...
Hence the testes and epididymides in which
the sperm cells develop, are located outside body cavity in the scrotum, where
the temperature is low
...
An average testis
is 4-5 cm in length, 2-5cm in breadth
...
5-14g
...
Internally the testis contains several incomplete septa
...
The lobules contain
seminiferous tubules and interstitial cells or Leydig cells
...


epididymis

coiled seminiferous tubule
tunica albuginea
vas deferens
testis

Fig
...
12
...
L
...
of the Testis

The seminiferous tubules are extensive
...
These tubules through a set of
short, straight tubules open into tubular network called the rete
testis
...
Internally the tubules and ductules are lined by ciliated columnar epithelium
...


Epididymis : It is formed of extremely convoluted ductules coming out of the
testis
...
The maturation of sperm
cells occurs within the ductules of the epididymis
...
It becomes associated with the blood vessels and nerves that supply the testis
...
Thus the spermatic cord consists of (1) Vas deferens (2) testicular artery and venus plexus (3) lymph
vessels (4) nerves (5) fibrous processes and muscles
...
The end of the vas deferns enlarges to form the ampulla
...
They help to propel the sperm cells through the ductus
deferens
...
It joins the ductus deferens to form the ejaculatory
duct
...
5 cm long
...


Urethra : The male urethra extends from the urinary bladder to the distal end
of the penis
...
It is a passageway for both urine and
reproductive fluids
...
They are
1
...

2
...


3
...
It extends from the membranous urethra, through the length of the
penis
...


Penis - It is the male copulatory organ
...
The radix attaches the penis to the
lower abdomen
...
It is covered by a loose
skin
...
3
...
3
...
S of Penis

142

The corpus of the penis consists of three masses of erectile tissue
...
These tissues are the right and left corpora cavernosa and the median
corpus spongiosum penis
...
The corpus sporgiosum penis surrounds the urethra and near the
end of the penis it expands into a conical, glans penis
...

The skin over the penis is thin
...
At the tip of the penis it is folded to form the prepuce or the
foreskin
...
The corona glandis and penile neck
have numerous preputial glands
...
Each vesicle is about 5 cm long
...

Prostate - It is a firm structure
...
It is found around the beginning of the male urethra
...
It weighs about 8g
...

After the middle age the prostate often enlarges
...


Bulbo-urethral gland - These are two glands
...
They lie lateral to the membranous urethra
...


Scrotum - It is a fibromuscular sac
...
It is divided into right and left by cutaneous raphe
...
The external appearence varies according to age and body temperature
...
It has numerous sweat glands and
nerve endings
...
Externally the organs are the mons pubis, labia majora and labia minora, clitoris and vestibular glands
...
The two ovaries are placed on each
side of the uterus in the pelvic region
...
Each
ovary is almond shaped
...
5cm wide and 1cm thick
...
3
...
4
...
The ovary is further supported
by suspensory and ovarian ligaments
...
It consists of a single layer of cuboidal cells
...
It is made of collagenous tissue
...
3
...
5
...
The cortex region contains the ovarian follicles
...
It receives blood vessels and nerves at the hilum
...
It contains ovarian follicles and corpora lutea of various sizes
...
The cortex is filled with stroma
composed of collagen
...


Ovarian follicles
The formation of the female gamete has many different phases and it
is complex
...
They contain primary oocytes (about 25mm in
diameter)
...
The follicles undergo changes as the female attains puberty
...
Primary follicle - The follicle cells are converted from squamous to cuboidal
cells
...
The oocyte increases in size
...
The follicular cells divide and form granulosa cells
...
Secondary follicle - It is about 20µm thick
...
The inner
and outer theca become prominent
...


3
...
It increases
in size (2mm diameter)
...
The oocyte and
ring of cells surrounding the oocyte (corona radiata) break away and float
freely in the follicular fluid
...

The ovary of the foetus at 5 months gestation has 7 million oocytes
...
Due to further
degeneration at the time of puberty only about 40,000 oocytes remain
...


Corpus luteum - It is formed after ovulation
...
The granulosa cells of the theca externa get
enlarged
...
They secrete hormones
...
Otherwise, it degenerates after 10-12
days
...
It becomes white in colour and
is now called as the corpus albicans
...

145

Uterine tubes (Fallopian tubes) - There are two uterine tubes or oviducts,
one on each side of the uterus
...
Each
tube is about 10 cm length
...
It opens into the peritoneal cavity
...
The uterine tube consists of three parts
...
It is the longest part
...
It is narrow
...

fundus
isthmus
ovary

uterine part
endometrium
myometrium
perimetrium
cervical canal
ostium

Uterus
cervix

vagina

Fig
...
12
...
Human female reproductive system

Uterus
It is a hollow thick walled muscular organ
...
It is
about 7
...
It weighs about 50g
...
Its larger rounded part
is called as the fundus
...
The cervix
is directed inferiorly
...
The uterus
continues as the cervical canal and opens into the vagina through a opening
called the ostium
...
The outermost layer is the
perimetrium or serous layer
...
The
innermost layer is the endometrium or mucous membrane
...
It undergoes menstrual changes and sloughing during
female sex cycle
...
It is a fibromuscular tube
...
It extends from the uterus to the outside
...

146

External Genitalia
Vestibule - The external female genitalia is known as the vulva or pudendum
...
The vestibular
region remains in between the two labia majora
...
The vestibular region is surrounded by the
mons pubis anteriorly and labia majora and labia minora on the lateral
sides
...
It is made up of
subcutaneous adipose connective tissue
...
It corresponds to similar structure in the male
...
They form the outer
boundary for the vestibule
...
They
remain nearer to the vaginal opening
...
It is an erectile structure
...
It is a sensitive region having
sensory receptors
...
It is found within the vaginal orifice or opening
...
In young women the hymen
may normally get torn during physical exercise
...
It has no established function
...
5 cm below the clitoris
...
It remains as a small cleft
...
The cornified region of the skin is formed of
a) stratum lucidum

b) stratum basale

c) stratum spinosum

d) stratum corneum

2
...
The number of facial bones are
a) 26

b) 25

c) 14

d) 22

4
...
The broadest muscles are named as
a) deltoid

b) gracilis

c) longus

d) lattismus

6
...
The largest salivary glands are
a) parotid

b)submandibular glands

c) sublingual glands

d) labial glands

8
...
8 m

c) 9 cm

d) 25 cm

148

9
...
The reduction in blood pressure may be caused due to
a) distributing vessels

b) resistance vessel

c) exchange vessels

d) reservoir vessels

11
...
The wall of the blood vessels are supplied with blood by
a) vasa nervosum

b) exchange vessels

c) vasa vasorum

d) capacitance vessels

13
...
The synapses are formed between
a) nerves and muscles

b) nerve tissues

c) capillaries

d) organs

15
...
The interoccular pressure is maintained by
a) aqueous humor

b) vitreous humor

c) cerebro spinal fluid

d) lymph fluid

17
...
The average weight of human thyroid gland is
a) 10 gms

b) 20 gms

c) 500 gms

d) 20 kg

19
...
What is keratinization ?
2
...
What is a synovial joint ?
4
...

5
...
Provide the human dental formula
7
...
Provide the root of systemic circulation
9
...
What is a neuromuscular junction ?
11
...
What is melbomian gland ?
13
...
What are podocytes ?
15
...
Give an account of the nail and its structure
2
...
Give an account of the muscles of the lower limb
4
...
Describe the paired and unpaired cartitages of larynx

150

6
...
Give on account of the thymus
8
...
Explain the organization of the lacrimal apparatus in human eye
10
...
Provide the structure of human kidney
12
...
Write an essay on the structure and organization of the axial skeleton in
human beings
...
Give an account of the organs of digestion in the buccal cavity
3
...
Provide a detailed description of the anatomy of human brain
5
...
Write an essay on the human male primary sex organs and associated
structures
...
GENETICS
4
...
Introduction
Genetics is the study of inheritance or heredity
...

The history of Genetics is closely linked with the ancient cultural history of man
...
As settlers in early civilization they
started living as groups
...
The agricultural revolution in early human civilization opened
the doors for very rapid improvements in human culture
...
Several cultivation processes
evolved
...

Simultaneously they started domestication of animals
...
Gradually they understood their reproductive methods
...
The idea of Genetics was adopted in
everyday practice
...
He did hybridization experiments in Pisum sativum more
out of curiosity and his devotion to science
...

Since the ‘rediscovery’ of Mendelism in 1900, Genetics has made rapid
developments
...
As of to-day all processes and causes for inheritance are well
understood
...
However, the steady processes of dominance of human beings on earth through
their knowledge of science and skill in technology will also ensure the safety
of earth in the times to come
...


4
...
It means that each gene has two alternative forms or
alleles and their expression are knwon as allelomorphs
...
However, some genetical characters are
determined by several forms of an allele known as multiple alleles
...

1
...
Of these, the chinchilla variety is
lighter in colour
...


Coloured(agouti)

Chinchilla

Himalayan albino

Albino

Fig
...
1
...
Different colours in Rabbit

A crossing of a homozygous coloured rabbit with an albino resulted in
following F1 and F2 generation
...


This result shows that coloured condition is dominant over albino
...

Parents

c ch c ch
(chinchilla)

x

c ac a
(albino)

F1

cch ca
(light grey)

x

c ch ca

F2

c ch c ch
25%
(chinchilla)

c ch c a
c ac a
50%
25%
(light grey) (albino)

In chinchilla, coat colour is lighter than the coloured (agouti)
...
However F 1 hybrids between
chinchilla and himalayan albino (Cchch) or between chinchilla and albino (c chca)
show light grey skin colour
...

Genotype

Phenotype

CC, Ccch, Cca ,Cch

coloured (wild)
154

c ch c ch

chinchilla

cch ch ,cchc a

light grey

ch ch ,chc a

himalayan albino

c ac a

albino

2
...

Landsteiner
...
There
can be two anitigens A or B in the blood, resulting in four blood groups, namely
A,B, AB and O
...

The inheritance of ABO system illustrates a new principle in genetic
control of phenotypes
...
With these antigens A and B
there are certain naturally occurrring antibodies in the serum of the blood
...
The presence of antigens and antibodies
occur as follows
Blood groups
A
B
AB
O

Antigen

Antibody in the serum

A
B
A and B
None

anti B
anti A
None
anti A and B

Antibodies in the blood of ‘group A’ will agglutinize red blood corpuscles
of the blood group B
...
Since no antibody is found in ‘group
AB’ blood, it will not agglutinize any other group
...
Hence ‘group O’ will agglitinize group A and B
...

Blood group of the donor

Blood group of the recipient

A

A and AB

B

B and AB
155

AB

AB

O

O, A, B, AB

From the table provided it is obvious that ‘group AB’ is universal
recipient
...

The gene for ABO system is conventionally represented by the sym
bol ‘I’
...
Thus
the genes can result in 6 possible genotypes but four possible phenotypes as
found in the table
Blood group

Possible genotype

O

I oIo

A

IAIA or IAIO

B

IBIB or IBIO

AB

I AIB

The alleles IA and IB jointly express themselves in the individual, they
are codminant
...


Disputed parentage and blood groups
The identification of blood group may help to decide in cases concerned with parentage issues
...
The impossibility of a particular blood group in the progeny can also be pointed out
...
It was initially discovered in rabbits, immunized with the blood of Rhesus
monkey
...
Wrong transfusion can cause agglutination of blood in the
recipient Hence before transfusion of blood, along with identification of ABO
blood group, it is necessary to test compatibility of Rh factor
...
Even though such an unfortunate incident may not happen in the first pregnancy, it could occur in successive pregnancies
...

This disease is called erythroblastosis fetalis
...
2
...
The continuous variations show the whole range of variations in a
particular character
...

Mendel in his work depended on sharp or alternate characters comprising discontinuous variations
...
Crossing F1 plants, produced only tall
and dwarf plants in the F2 generation
...

However, by the end of the 19 th century Galton, a British geneticist
and statistician was interested in the study of continuous variations
...
He called these characters as metrical characters and found them inherited
...
They were the mendelians and the biometricians
...
These two views remained contradictory
...

Yule (1906) suggested that quantitative variations may be controlled
157

by large number of individual genes, with each gene having a small effect
...
The hereditary processes operating through such system was explained through multiple
factor hypothesis
...
B
...
In USA, marriages between black and white individuals has resulted in
a population known as mulattoes
...
When the mulattoes marry among themselves, all shades of
skin colours are obtained
...
The genotypes
of mulattoes will be AaBb
...
The observed results on number of
individuals with differing shades indicate the involvement of four or five gene
pairs in the control of skin colour
...

Studies have also shown that, the control of most characteristics are
multifactorial
...

An understanding of the polygenic influence on a specific genetic trait
requires enormous data
...

From such studies it becomes clear that while at individual level the
basic inheritance remains mendelian, at the population level it appears much
more complicated
...
3 Sex Determination
Differentiation as male and female sex and reproduction through sexual
processes are basic phenomena in the living world
...
It is achieved through effecient
functional anatomy of male and female individuals
...
Morphological, Physiological and behavioural characters exhibited by
158

male and female of a speices are called the secondary sexual characters
...

The fundamental mechanism concerned with sex determination are
genitical in nature
...


A
...
He observed gametogenesis in grasshopper (Xiphidium fasciatum)
...
Similar
observations were made in bugs and beetles by several other workers
...
Among them the chromosomes concerned
with body or somatic characters were named as autosomes (A)
...

Later it was found that sex chromosomes (X and Y) had structural
differences
...
The Y-chromosome was found
to be smaller with one end curved or bent to one side (as in Drosophila)
...
Heterogametic males 2
...

Heterogametic males :- In this type of sex determination the female has
two x-chromosomes
...
During gametogenesis the males could produce two types of gametes ie
...
Hence the males
could be called the heterogametic sex
...
, all eggs having one ‘X’-chromosome each
...
Each type of sex determination has subtypes as shown in the table
...
Genic balance mechanism
Further studies on sex determination showed that sex determination
was not the inheritance of genes by the sex chromosomes alone
...
Thus the genic balance mechanism of
sex was discovered
...
B Bridges in 1921
...
For sex determination,
each haploid set of autosomes carry factors with a male determining value
equal to one (1)
...
5 )
...
5(‘A’ represents a haploid set of
autosomes)
...
A normal female
(AAXX) has the male female determination ratio of 2:3
...

Female

Male

autosomes
sex chromosomes
Chromosomes

Chromosomes
Fig
...
3
...
Drosophila flies

160

Phenotype
Super female
Triploid
Normal
Tetraploid
female
Diploid
Haploid
Intersex
Normal male
Super male

Number of X
chromosomes
3
3
4
2
1
2
1
1

Sets
Autosomes
2
3
4
2
1
3
2
3

X/A ratio
1
...
0
1
...
0
1
...
67
0
...
33

Sex determination in Human beings
The human sex determination mechanism to a larger extent resembles XX - XY type of Drosophila
...

Thus in human beings, the presence of Y chromosome determines maleness and its absence determines femaleness
...


Sex anomalies in Human beings
1
...
They have webbed neck, broad shield-shaped
chest, low intelligence, under developed breasts and poorly developed ovaries
...
This abnormality is known as Turner’s
syndrome
...
Klinefelter’s syndrome :- This syndrome is caused due to the presence
of an extra X chromosome in males
...
The zygote
will have three sex chromosomes (XXY)
...
The symptoms of this syndrome are the presence of small
testicles, mental retardation, longer arms and high pitched voice
...
Super females :- These females are also known as Poly X females
...
The poly
X females are mentally retarded and sterile
...
XYY males :- Such males will have an extra Y chromosome (XYY)
...

5
...
The person will have both ovarian and testicular tissues
...


C
...

This mechanism is also known as arrhenotokus parthenogenesis
...
In these insects, fertilized eggs develop into diploid females and unfertilized egg into haploid males
...

They are the fertilized and unfertilized eggs
...
The diploid female zygote
can develop either into a queen or a sterile female worker bee
...
The haploid zygote develops into a male
...

Apart from genetical systems, the sexuality can also be controlled by various factors such as metabolism, environment and hormones
...
Its sex determination was
studied by F
...
The adult female worm is about 2
...
It
has a well defined anatomical organization
...
4
...
2
...
Its body organs are
rudimentary
...
All
larvae of Bonellia are genetically similar
...
If a larva develops in
isolation (ie
...
If a developing male is detached from the proboscis of female, it becomes an intersex
...


4
...
The inheritance of traits related to autosomes normally follows
Mendel’s laws
...
The genes
that occur only on X chromosomes are called as X - linked genes
...
The inheritance of X or Y linked genes is called as sex linked inheritance
...


X - Linked inheritance
T
...
Morgan (1910) in his studies on inheritance of genes in Drosophila discovered that the pattern of inheritance of certain traits were found to
vary with the sex of the parent and offspring
...
Further it was found to be recessive to another
X - linked, dominant gene for red eye colour
...

When the red eyed male and red eyed female of the F 1 were intercrossed, in
the F2 generation all the female flies were found to be red eyed
...


White eyed female x Red eyed male
When a white eyed female Drosophila is crossed with a red eyed
male, all the female individuals in the F1 generation are red eyed and all the
males are white eyed
...
Similarly the male population of F2
included 50 % red eyed and 50 % white eyed flies
...
4
...
1
...
There
are 150 confimed X- linked traits known
...

Colour blindness :
The human vision is basically due to cells called rods and cones found
on the retina of the eye
...
The formation of colour sensitive cones is controlled by a dominant Xlinked gene
...
Hence homozygous recessive females (XCXC) and Hemizygous
recessive males (XCY) are unable to differentiate between red and green colour
...


Colour - blind man x normal visioned woman
When a colour-blind man marries a normal woman in their F1 progeny
all children would be normal
...
If that female gets married to a normal male in the F 2 generation normal and colour-blind nature will occur in 3 : 1 ratio
...
5 Pleiotropy
It is an established fact that a specific gene controls a specific
phenotypic trait
...
Studies on ‘gene expression’
have revealed that a gene often influences more than one phenotypic trait
...

In such a genic influence more conspicuous expression of a phenotypic trait
by a gene is called its major effect
...
Such genes responsible
for multiple effects are called pleiotropic genes
...
A keen observation has shown that this gene affects
other traits as well
...


165

Self Evaluation
Part-A
1
...
Rh
...
The type of sex determination in moths and butterflies is
a) xx - xo type
b) xx - xy type
c) zo - zz type
d) zw - zz type
4
...
5
b) 1
...
6
d) 0
...
Holandric genes occur exclusively on
a) x - chromosomes
b) y - chromosomes
c) autosomes
d) both x and y chromosomes
Part - B
Give very short answer
...
What are multiply alleles ?
7
...
Mention the possible genotypes of the offsprings if the parental blood groups
are B and B
...
What is the cause for the death of a child in erythroblastosis fetalis?
10
...
Who are mulattoes?
12
...
What is arrhenotokus parthenogenesis?
14
...

Part - C
Answer briefly
15
...
Discuss how ‘O’ blood group is considered as an universal donor
...
What is erythroblastosis fetalis?
18
...

19
...

20
...
Give an account of ABO blood groups in human beings
...
Explain genic balance mechanism of sex determination
...
What is sex - linked inheritance ? Give an account of x - linked inheritance in
Drosophila
...
Developmental Biology
The process of sexual reproduction ensures the formation of a diploid
zygote which could constitute the next generation
...
By an ontogenetic process the zygote undergoes various developmental phases resulting in multicellular embryonic organisation
...
Inspite of the fact that organisms vary in their structure, form and mode of life, the processes of
embryogenesis, development and differention are remarakably similar in all
metazoans
...
The ontogenetic stages also reflect the
historical development of species or phylogenetic development
...
There is a recorded history of
human natural curiosity in sexual reproduction from very early period
...
D
...

The earliest recorded work had been done by Aristotle (384-322 BC)
...
It describes the reproduction and development of many
kinds of animals
...
He compared
reproductive methods of different animals and provided a classification based
on that
...
For this speculative idea he provided the
name epigenesis
...
Thus
to-day he is regarded as the founder of the science of embryology
...
Through
the contributions made by various workers like Von Baer ,
E
...
Hertwig, E
...
M Child, Maclean
and others rapid advancements were being made in the understanding of de168

velopmental processes in animals
...
Such studies have paved
the way for meeting the challanges of to-day’s world through works on cloning techniques, tissue culture, stem cell researches, ‘in vitro’ fertilisation,
organ transplantations, regeneration, tissue grafting and other medical and
non-medical fields
...
Gametogenesis is the formation of sex
cells or reproductive cells or gametes
...
The male and female gonads, namely the testis and ovary
contain primordial germ cells
...

A

spermatogonium

B

mitosis

growth phase
primary
spermatocyte

oogonium

growth phase
meiotic division
oocyte

secondary
spermatocyte
spermatid
ootid

first polar body
spermatozoan
second polar body
1 ripe egg

3 polar bodies

Fig
...
1
...
A-Spermatogenesis - B-Oogenesis

Spermatogenesis :
In the testis of vertebrates the specialised tissue for the process of
spermatogenesis are located in the seminiferous tubules
...
Through a growth phase the speramtogonia
get converted into primary spermatocytes
...
They
undergo meiotic cell division
...
Through II Meiosis they form spermatids
...
By a process of spermiogenesis or
spermioteliosis they get differentiated into specialized cells called
spermatozoa
...
This process that happens in the primordial germ
cell of the ovary passes through stages of primary oogonia, primary oocyte
and secondary oocyte
...

Thus the final product, namely the ovum is a haploid female reproductive cell
...
Fertilization provides the diploid nature to the cell
...
Further, the process of fertilization
triggers or initiates the initial stages of embryogenesis
...
The entry of sperm initiates further changes in the
egg
...
This process of nuclear fusion is known as syngamy or amphimixis
...
1
...

The amount of food needed varies for different organisms
...
Food is provided in the form of yolk
...
It is provided by the ovary during
differentiation of the egg
...
In amphibian eggs yolk occurs in the form of large granules,
called yolk platelets
...

The amount of yolk is an important determining factor for further patterns in embryological stages
...

170

The eggs can be classified based on amount and distribution of yolk
...

The final ‘young one’ born may be very simple in structure and organization
...
In the eggs of such organisms due to brevity of the
growth period the amount of yolk is much reduced
...

In certain other animals the eggs need to release young ones in a more
self supportive condition
...
Such eggs with moderate amount of yolk are called mesolecithal eggs
...

In some animals the growth and differentiation of the embryo is much
more elaborate
...
Hence for supporting
the embryo in development the eggs contain large quantity of yolk
...
The eggs of reptiles
and birds are considered as macrolecithal
...
It is a protective structure for laying the eggs on lands
...


shell

disc of cytoplasm
yolk

shell membrane
air space
chalaza

albumen
vitelline membrane
Fig
...
1
...
Hen’s egg

Distribution of yolk
...
According to the pattern of dispersal of yolk the following egg types had been identified
...
Homolecithal or isolecithal eggs
...
The
distribution is somewhat uniform in animal, vegetal poles and the equatorial
animal pole

vegetal pole
Fig
...
1
...
Isolecithal egg

region
...
All microlecithal eggs have this nature
...
Telolecithal eggs
...
5
...
4
...
In polarity, the eggs have an innate nature for
to be differentiated into upper animal pole and lower vegetal pole
...
The
yolk in the egg will normally get concentrated in the vegetal pole
...
The extent of
vegetal pole is determined by the amount of yolk
...
Mesolecithal and macrolecithal eggs remain as telolecithal eggs
...
Centrolecithal eggs
...
5
...
5
...
In invertebrate animals oval
shaped eggs are seen
...
In insects the eggs are oval in shape and
the yolk remains in the centre of the egg
...


5
...

The process of cleavage reamains one of the earliest mechanical activity in the conversion of a single celled egg into a multicellular embryo
...
However in parthenogenetic eggs
cleavage can commence without the influence of fertilization
...
These divisions result in cells called blastomeres
...

The first cleavage of frog’s egg was observed by Swammerdam in
1738
...
With the development of microscopes cleavages and
further stages were observed in the eggs of sea urchin, star fishes, amphioxus
and hen’s eggs
...
The mitotic process is very rapid
...
As the cleavage
progresses the resultant daughter cells, namely the blastomeres get reduced
in size
...
The total size
and volume of the embryo remains the same
...
It gets transformed into blastula
...


The planes of cleavage
An egg can be divided from different planes during cleavage
...

1
...
It bisects both the poles of the egg
...

173

2
...
The furrows pass from animal to vegital pole
...

3
...
It lies on the equatorial plane
...

4
...
It is also called as transverse or horizontal
cleavage
...
However the fertilized
egg has to undergo all stages of development and result in a suitable ‘young
form’ initiating next generation
...
The initial influence of yolk is felt during the process of
cleavage
...
Accordingly several cleavage patterns have been recognised
...
Total or holoblastic cleavage - In this type the cleavage furrow bisects
the entire egg
...

(a) Equal holoblastic cleavage - In microlecithal and isolecithal eggs, cleavage leads to the formation of blastomeres of equal size
...

(b) Unequal holoblastic cleavage - In mesolecithal and telolocithal eggs,
cleavage leads to the formation of blastomeres of unequal size
...

2
...
Meroblastic cleavage
may be of two types
...
Hence
cleavage furrows can be formed only in the disc-like animal pole region
...
Eg: birds and reptiles
...
Eg: insects
...
However, all cleavages follow a common procedure
...

1
...

i) Cells tend to divide into equal daughter cells
ii) Each new division plane tends to intersect the preceding plane at right
angles
...
Balfour’s law (Balfour 1885) - “The speed or rate of cleavage in any
region of egg is inversely proportional to the amount of yolk it contains”
...

In frog’s egg the cleavage is holoblastic and unequal
...

meridional

latitudinal

meridional
third cleavage
first cleavage
blastoderm
blastocoele

second cleavage

blastula-L
...
5
...
1
...
The first cleavage plane is meridional
...
It gradually extends towards the vegetal pole of the egg
...

2
...
It bisects the first cleavage furrow at right angles
...
It results in the formation of four blastomeres
...
In the next stage a latitudinal furrow is formed above the horizontal furrow nearer to the animal pole
...
The latitudinal furrow uniformly affects all
the blastomeres
...
Four of them
remaining in the vegetal pole are large
...

Another four blastomeres remain in the vegetal pole
...
The micromeres are smaller in size than the macromeres
...
The fourth set of cleavage planes are meridional and holoblastic
...
They divide yolkless micromeres more rapidly than yolk-rich macromeres
...

5
...

A closer observation reveals that, while the blastomeres above the equator
are small and remain as micromeres, the blastomeres of the vegetal pole remain progressively larger
...

animal pole
micromere
blastocoele
macromere
vegetal pole
Fig
...
2
...
L
...
In this stage it is called the morula
...
Gradually the blastocoelic
space increases into a large cavity occuping the middle of the blastula
...

The blastomeres gradually adhere to each other, and arrange themselves into a true epithelium called the blastoderm
...
The embryo having a fluid-filled blastocoele
and blastoderm is called the blastula
...
The blastula moves to the next stage, namely gastrulation at
a stage in which it has about 20,000 cells
...
The fate of each and
every blastomere has been observed and marked
...
This map shows
prospective ectoderm, mesoderm and endodermal areas
...


5
...
Gastrulation in frog embryo
The process of gastrulation is a continuous activity succeeding, cleavage
...
They wander
and occupy their prospective organ forming zones
...

At a specific region below the equator the blastoderm cells assume an
elongated bottle like shape
...
As
the cells move further inside, an invagination happens
...
The
opening of the archenteron on the surface of the blastula is called the
blastopore
...
Finally it becomes circular
...
The lower edge may be called the ‘ventral lip’
...
5
...
1
...
These inwandering of
cells is termed as involution
...
5
...
2
...
These cells move to the interior
...
The inwandering cells gradually occupy the region of the blastocoele
...
A new cavity among the
involuted cells results
...
The gastrocoel later becomes the archenteron
...
This region remains as the foregut
...

The inward movement of the exterior cells through the blastoporal
region is called involution
...

micromere
blastocoele
dorsal lip

macromere
ectoderm
endoderm
gastrocoele

blastopore

yolk plug
mesoderm
Fig
...
3
...
Gastrulation of Frog

The mesodermal cells occupy the region between inner endodermal
and outer ectodermal cells
...
The expansion of the
ectoderm is due to epiboly
...

The blastopore is gradually covered by certain endoderm cells
...
Gradually the
yolk-plug withdraws to the interior and the blastopore gets reduced into a
narrow slit
...
Gradually the gastrula undergoes
the process of tubulation or neurulation to become a neurula
...
5
...
4
...
5
...
5
...
However
during this process mesoderm and endoderm also undergo differentiation
...

The dorsal side of the gastrula is lined by ectodermal cells
...
It
remains as medullary plate or nerual plate
...
In the
middle of the neural fold a neural groove appears
...
The neural folds above the groove
...
This tube gets detached from the surface
...
The embryo at this
stage is called the neurula
...


neural plate
neural fold
blasto pore
neuropore

A

B

C
Fig
...
3
...
Neurulation of frog embryo

The post-neurular development of frog involves the formation of all
body organs
...
4
...
In the next stage the primary organ rudiments subdivide into secondary
organ rudiments
...


The development of ectodermal organs
The neurula of frog has three kinds of ectodermal tissues namely, epidermal ectoderm, neural ectoderm and neural crest cells
...

180

Neural ectoderm
This layer of cells form the central nervous system and peripheral
nervous systems
...


The development of endodermal organs
The predominant endodermal organs are the organs of the alimentary
canal, lungs, pancreas and urinary bladder
...
It develops on the ventral side
of pharynx
...
Initially the heart is
formed as a straight tube
...

Self Evaluation
Part - A
Choose the right answer
1
...
Centrolecithal eggs are produced by
a) frog
b) human beings
c) reptiles
d) insects
3
...
Sach’s law is related to
a) gametogenesis
b) cleavage
c) gastrulation
d) organogenesis
181

5
...
Provide a list of various stages in the embryology of animals
2
...

3
...

4
...
What is a morula?
6
...

7
...
What is a ‘fate map’ ?
9
...
Give an account of the megalecithal egg
...
What is a centrolecithal egg
...
Provide a general account on cleavage
...
What is sach’s law?
5
...
Provide a detailed account on the types of eggs
...
Give an account on the cleavage of fertilized egg
...
Describe how the process of gastrulation occurs in the egg of an amphibian
4
...


182

6
...
While some animals are very useful to mankind certain others
cause loss to the economy of man
...
Some pests are competitors of human beings for natural resources and food
...


6
...
Beneficial animals
The animals contributing to our economy and welfare are known as
beneficial animals
...
The silk worms, the honey bees, the lac insects, fowls,
fishes, prawns and crabs belong to this category
...
1
...

Coral rocks are actually the skeletal remains, primarily of calcium carbonate
secreted by living coral polyps
...

All reef building corals live as large colonies
...
During the day, polyps are withdrawn into skeletal
cups and the corals appear more or less lifeless
...
The reef looks like a field of flowers
...
Only in warmer waters, the
coral polyps can extract calcium from the sea water and deposit it as calcium
carbonate in their skeletons
...

Small plants like Zooxanthella living in the coral tissue contribute to
the yellow, brown and green colours of some reef forming corals
...

183

Formation of coral reefs
Corals are best known for the massive rocky reefs they build in tropics
...
These larvae initially lead a
free swimming life
...
A coral reef is thus a result of the activity
of millions of coral polyps over several thousand years
...
6
...
1
...
In India coral reefs occur in the Lakshadweep, Andaman and
Nicobar Islands and in the south east-coast
...
At the southern end of
Indian peninsula, this type is seen as a chain of well developed reefs starting
from Rameshwaram Island and extending beyond Tuticorin
...

Barrier Reefs are situated away from the coast and form off-shore
break waters parallel to the coasts or isolated islands
...

Atolls consist of a ring shaped reef, encircling a shallow lagoon which is
connected to the outside by an opening
...

184

High tide
Low tide
Coral reef

Coral reef

Volcanic island
Cross section of fringing reef

Lagoon

High tide
Low tide

Lagoon

Coral reef

Coral reef
C
...
of Barrier reef
Lagoon

Coral reef

High tide
Low tide
Coral reef

C
...
of an Atoll reef
Fig
...
1
...
Coral reef - Types

Economic importance
Some corals are highly priced for their decorative value
...
rubrum ) are used in jewellery and
ornaments
...
The organ
pipe coral (Tubipora) is used in indigenous system of medicine in South India
...
Corals serve as raw
materials for the preparation of lime mortar and cement because of their
calcium carbonate content
...
Coral skeletons act as
natural barriers against sea erosion and cyclonic storms
...

185

Coral reefs provide a unique habitat for large and diverse variety of
organisms
...

In several countries Fringing reef, Barrier reef and Atolls are helping
in the tourism industry
...
1
...
Waste
materials introduced into the environment are of two types namely
non-degradable and degradable wastes
...

Waste biomass from agriculture, domestic, urban and industrial sources
remains the main cause of organic pollution in many countries, including India
...

New technologies are now available for recycling some of these solid
wastes
...

India produces about 2500 million tonnes of organic wastes annually
...

Vermiculture :In recent years vermiculture has received much attention in many
countries
...
Further the worms also
play an important role in waste disposal
...
A single earthworm can produce 1000 to
1500 offsprings in a year
...

Selection of earthworm species and their culture
Lampito mauritii and Perionyx excavator are cultured in India and
Thailand
...
Amynthas hawayana, Eisenia foetida and Eudrilus engeniae are
also commonly used for waste management
...
A
cultured worm must be able to adapt to substrates, grow fast and breed or
multiply readily under controlled conditions
...
4m long, 1
...
6m deep appears
to be very satisfactory for a population of more than 50,000 earthworms
...
Soil, organic matter, manure, leaves, rice
straw, dried water hyacinth, saw dust and any fermented substrate can be
used as a culture medium to raise worms in boxes or containers
...
Any decayed organic matter appears to be good
food for worms but the feed should not be contaminated by detergents or
insecticides
...
They are also used as livestock feed in poultry
industry
...
The breakdown of these materials or the
degrades of organic matter by worm activity is called ‘Vermicompost’ It is a
better source of organic manure
...
1
...
Many insects are beneficial to man
...
They are Productive and Helpful insects
...
Productive Insects
These insects produce certain substances which are useful to humans
...

187

A
...
They live as colonies
...
They feed on the pollen and nectar of flowers
...
Of these, only three species
are useful in collecting honey
...
Apis dorsata (Rock bee)
...
It
produces plenty of honey
...
It is not possible to domesticate them for
the bee keeping industry
...
Apis florea : This is the smallest of the three species and is known as the
little bee
...
They are found hanging
from bushes and corners of roof
...
Apis indica : This is the common Indian honey bee
...
dorsata and A
...
This bee builds several parallel combs,
generally in hollows of trees, on the walls, inside wells, caves and similar
protected spots
...

The honeybees collect nectar from various flowers
...
In its stomach due to the action of enzymes certain
changes happen to the nectar
...

Apiculture or Bee keeping is the technique of rearing honey bees
for honey and wax from their comb or beehives
...
Its colour and smell varies in
accordance with the nectar collected from different flowers
...
5 litres of milk or 1
...
One gram of honey provides
approxmately 33k
...
Honey has laxative, antiseptic and sedative
charcteristics
...
It is
helpful in building up the haemoglobin of the blood
...
It cures ulcers on tongue and alimentary canal
...

Beeswax is also a natural secretion of the worker bee from the glands
located in the abdomen
...
It is also used in microtomy for block preparation of tissues
...
Silk worms

Adult male
Fig
...
1
...
Silkmoth

Adult female

Silk is another valuable product from the insect world
...
Sericulture is the scientific management of production and marketing of natural
silk from silkworms
...
Mulberry silkworm - Bombyx mori : This is a completely domesticated
insect
...
The silk produced by this moth is white in colour
...

2
...
The cocoon produced by this worm is smooth and hard
...
The cocoon
yields reelable, brown coloured Tasar silk
...
Muga Silk worm: Antheraea assamensis: The native place of this species is Assam where it has now become a good source of cottage industry
...

4
...
The cocoons of
this worm have very loose texture and the silk produced is called as Arandi
silk locally
...

The sericulture plays a significant role in the rural economy of our
country
...
It was kept as a
189

secret for several centuries
...

Uses of silk
The raw silk is used in the manufacture of woven materials, knitted
fabrics and garments
...

C
...
Lac is the resinous
protective secretion produced by a kind of scale insect called Laccifer lacca
...
The minute red
coloured larva of this insect, settles on succulent shoots of the host plants
...
The twigs
are harvested and the encrustations scraped, dried and processed to yield the
lac of commerce
...
6
...
4
...
These trees are common in the western ghats
...
It has a
unique combination of properties which render it useful in the plastics,
electrical, adhesive, leather, wood finishing and other industries
...
It possesses very good adhesion to mica
...
It
190

is a principal ingredient of sealing wax
...

II
...
The most
important of these helpful insects are the insect feeding or entomophagous forms including predators and parasites
...

Insect - Predators
These are generally larger than their prey
...
Among the insect predators, lady bird beetles are
more useful to the farmers and gardeners
...
Both larvae and adults feed on a wide
range of insects
...


Ladybird beetle

Aphis lion

Ground beetle

Fig
...
1
...
Insect - predators

Insect parasites
Insect parasites are smaller than their hosts
...
The
tachinid flies parasitize caterpillars, beetles and other groups of insects
...
Most group of insects are
plagued by ichneumon parasites
...

191

Tascinid fly
Pupae of Tacinid fly on a caterpillar

Pupae of a braconid fly on the
Ichneumon wasp laying eggs
larva of a moth
in a caterpillar
Fig
...
1
...
Insect parasites

Insects as pollinators
Insects play an important role in the pollination of plants
...
The
services of honey bees are needed in the production of cultivated crops, such
as apples, pears, plums and vegetables
...

Other useful insects
A number of insects feed on plants and they may aid in keeping plant
weeds under control
...


6
...
4 Prawns, Lobsters and Crabs
A
...
It helps to earn a sizeable amount of foreign exchange
...
Therefore, they are in great demand both in the local and international
markets
...
Apart from being a delicacy,
prawns are a rich source of protein and vitamins (A and D)
...
As they contain very little fat, they have
become a favourite protein food for the weight conscious persons
...
monodon, P
...
monoceros M
...
brevicornis, Parapenaeopsis stylifera,
P
...
malcomsonii, Palaeomon
tenuipes and P
...
6
...
7
...

They migrate to brackish water for breeding
...
Macrobrachium,
Palaeomon
...
They form large
shoals close to malabar coast during the monsoon season
...
The practice of rearing prawns as a ‘secondary crop’ between
November and April in the paddy fields along the coastal areas in India should
be a step towards increased production of fresh water prawns
...
Large specimens are frozen directly between layers of ice
...
Prawns are
also cured
...


193

B
...
They are clawed or true
lobsters, spiny or rock lobsters, sand or slipper lobsters and coral lobsters
...
The economically
important species of spiny lobsters are Palinurus polyphagus P
...
ornatus and P
...
The lobsters are called ‘fš Ïuhš’(Kal Eral)
in Tamil
...
6
...
8
...
Its food
value (proteins 15-24 %) was realised following the demand for lobsters in
western countries
...
The main lobster landing centres in India are Mumbai, Veraval,
Kolachal, Tuticorin, Chennai, Mandapam and Kozhikode
...
polyphagus being the
dominant species
...
polyphagus and P
...
polyphagus and P
...
In
the Gulf of mannar the lobster fishery is confined to the areas where coral
reefs are present
...

The lobsters are esteemed as good food particularly in foreign
countries
...

The central Marine fisheries Research Institute (CMFRI) has carried
out studies on fishery, recruitment, biology, physiology, breeding, larval
rearing and culture of economically important spiny lobsters in India
...
The Crabs
The crabs are decapod crustaceans
...
The abdomen in crabs shows sexual
dimorphism
...
In female crab the abdomen is
broad
...

There are nearly six hundred crab species occurring in the Indian waters
but only very few of them are being used for food purposes
...


6
...
5 Pearl Oyster
Pearls are one of the rarest and highly esteemed gems
...

From the point of view of pearl production in Indian waters, the most
important species is P
...
It has a wide distribution in the Persian Gulf,
Red sea, Gulf of Kutch, Gulf of Mannar and the Palk Bay
...
These formations are known as ‘pearl banks’ or ‘paars’
...
Heavy production
had been recorded in Tuticorin
...
6
...
9
...
6
...
10
...
Every
oyster contains a pearl
...
Some of
them are large, perfectly round with fine lustre fetching high prices
...
In recent years
India has succeeded in developing farming techniques for the production of
cultured pearls of good shape and lustre
...
In this process shell beads are introduced into the soft tissues of the
oyster along with a strip of the mantle so that the latter may secrete the pearly
substance around the bead
...
Thus, cultured pearls are produced in the same way as the natural pearls
...
It is like the nacreous
layer secreted by the mantle on the inner surface of the shell valve
...
They are collected for the manufacture of buttons and
other fancy articles
...
1
...
Besides,
the major capture fisheries, a breakthrough has been effected in recent years
to initiate the culture of selected species of finfishes and crustaceans
...

Consumption of fish for food has appreciably increased in recent years in all
countries
...
In India there is good scope
for development of marine resources to derive economic, social and
nutritional benefits
...
Fish flesh is an excellent source of protein in human diet
...

Protein constitutes about 20 percent
...
Fish flesh remains a good source for
all essential aminoacids in needed concentrations
...
As a child food, fish is easily tolerated by infants
...

The nutritive value of preserved and processed fish and fishery
product is generally lower than that of raw fish
...
Chief among these are :
Fish liver oil
Fish liver contains vitamin A and D in considerable quantities
...

shark liver oil and cod liver oil
...
Fish liver oil will ensure healthy growth of bones and teeth
...
Fish body oil is
generally extracted from oil sardines or from less edible varieties of fishes
...
Some of the
important uses of oil are : 1) manufacture of cheap soaps, paints and varnishes 2) tanning of leather 3) steel and chemical industries 4) manufacture
of lubricants and candles
...

It makes an excellent poultry and animal feed
...

Fish flour :
Fish flour is considered an ideal protein source to supplement diet of
both adults and infants
...
It is
also used to enrich bakery products such as cakes, breads, biscuits, soup and
sweets
...
Fish guano is obtained as waste from fish oil
industries
...

Fish Glue :
It is a kind of good glue obtained from fin trimmings, bones and skins
of fishes
...

Isinglass :
Isinglass is a high grade collagen produced from the air bladders of
certain groups of fishes
...
It is also used in the preparation of plasters and special cements
...

Omega Fatty acid
The unique feature which differentiates fish food from other animal
protein sources is the presence of omega-3 fatty acids such as linolenic acid,
decosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)
...
DHA is
essential for the foetal growth and development
...
It helps to control diabetis by
improving insulin action
...


6
...
7 Guano (Bird excreta)
Guano is the accumulated excrement or droppings of fish eating sea
birds such as gannets, cormorants and pelicans
...
These sea birds populate some islands off the west coast of Peru,
lower California and Africa
...
They may consume 1000 tonnes of fish daily
...
The Government protects the seafowls and processes the guano which
contains about 11 to 16% nitrogen, 8 to 12 % phosphoric acid and 2 to 3%
potash
...
The real guano is found in vast stratified accretions on
rainless islands off the coasts of Peru
...
1
...
They
are graceful in their shape, bodyform and movement
...
Thus, varieties of
gold fishes which are popular with aquarium lovers were bred by them from
ordinary carplike fishes
...

An Aquarium is a container made of glass, or with glass walls
...
It is a hobby which appeals to young and old and has opened up a
flourishing business in all big cities
...
While selecting a tank it is very important to note that it is of good
construction
...
Further
such tanks can accomodate more number of fishes
...
In
order to get a good view of both fishes and plants in an aquarium tank, the
light should come obliquely
...
To avail maximum sunlight an eastern exposure is
preferable
...
It is also essential to have a cover with a provision for installing lights
and feeding
...
Their
sides should be cleaned with 1 % potassium permanganate solution, besides
repeated washing with tap water
...
The sand for the tank bottom can be collected from the sea shore or a
river
...
It is advisable to put the
sand in a shallow pan or aluminium vessel and heating it
...
These processes ensure the killing of all
199

bacteria or germs
...
Over the top layer of sand a thin layer of stone chips or very small
pebbles may be placed
...
A tap water of domestic supply is likely to have chlorine which is
harmful to fish
...
If the water is hard it must be properly treated
...

Planting : The aquarium tank after being filled with water can be planted with
selected varieties of aquatic plants
...
Besides decorating the aquarium tank, they also help in spawning and as food for certain fishes
...
Over crowding of plants has to be avoided to ensure an
adequate supply of oxygen to fishes
...
Among them the important ones
are the tall rooted plants such as Vallisneria and Myriophyllum
...
Plants may be disinfected by rinsing in 0
...
The roots are trimmed and are kept between wet newspaper sheets to prevent them from drying before they are set
...
Large plants like vallisneria
may be planted at the back while the bushy plants can be placed in the corners
or at sides
...
The fragments of these plants are used by these fishes in the
construction of bubble nests for breeding
...
Fishes also require light to trace their food
...
Strong sunlight destroys bacteria and keeps the tank healthy
...
It is better to use fluorescent lighting for
promotion of plant growth and for even distribution of light
...
6
...
11
...

The number of fishes suitable for stocking in an aquarium tank
depends mainly on the surface area of the tank, its dissolved oxygen content
and size of the fish
...
Based on the above, a tank of 75 X 30 cm size for
example may hold three fishes each of 10 cm length
...
Before
introduction into the aquarium tank, the fish may be treated with 2 percent
potassium permanganate solution to avoid parasitic attack
...
Live protein rich foods
such as tubifex worms, Chironomid larvae and mosquito larvae are
considered excellent
...

Fishes may be fed once or twice a day according to their preference
and satiation
...
If the level of the water gets
reduced in course of time it should be restored by the addition of some rain
water or chlorine free tap water
...
The movements of colour fishes in an aquarium would
certainly please the ailing and convalescing people
...

Vivarium ( Zoo )
The growing awareness for nature and wild life conservation has made
zoos a popular institution
...
There are about 350 animal collections in
India, which are visited by more than 50 million people annually
...

202

The need for making conservation as one of the main objectives of
management of zoos was realised by Government of India soon after
independence
...
Today wildlife habitats are under severe pressure and a large
number of species of wild fauna have become endangered
...
As zoos are visited by a large number
of visitors, they are potent tools for educating people about the important of
wild life management as it remain a life supporting processe of nature
...
This objective can be
achieved through the following methods
...
Supporting the conservation of endangered species, which have no chance
of survival in wild
...
To inspire amongst zoo visitors empathy for wild animals, an understanding
and awareness about the need for conservation of natural resources and for
maintaining the ecological balance
...
Providing opportunities for scientific studies useful for conservation
...

List of important Zoos
1
...
P
...
Nehru Zoological park, Hydrabad, A
...

3
...

4
...

5
...

6
...

7
...

8
...
Mahendra Chaudhury Zoological park, Punjab
...
Arignar Anna Zoological park, Vandalur, Tamil Nadu
...
Kanpur Zoological park, Kanour, U
...

12
...


6
...
Human beings are affected directly or through bites or stings or
by transmission of various kinds of pathogens
...
For the convenience of our
study the harmful animals are grouped under the following categories namely
disease causing organisms, poisonous animals, fouling organisms and pests
...
2
...

Through the ages millions of people have died of dieases transmitted by
insects
...


Sand fly

Rat flea

House fly

Culex

Anopheles
Human louse

Mosquito
Fig
...
2
...
Insect - vectors

204

Sitting position of
mosquito species

1
...
They are closely associated with humans and thrive best where people are careless in the disposal of
wastes
...

They feed on all kinds of decaying and decomposing matter
...
) The housefly cause diseases through food contaminations
...
Populations of houseflies can be
controlled by proper disposal of manure, garbage, sewage, food waste,
human excreta and other organic materials
...
Insecticides may be used against larvae
...
5% tremephos are effective
...
Sand flies - Phlebotomus papatasi
These flies are 4 mm long
...
The males are non parasitic, feeding on
moisture
...
Through biting this
fly transmits the disease called kala-azar
...
During the day time the flies remain hiding
...
The sand fly attacks during night times
...
In side the
body of the fly, the parasite undergoes changes
...
The
parasites mostly concentrate in the capillaries of spleen, liver and bone marrow
...

Control :
Spraying of 5 % DDT / BHC easily kills the flies
...

3
...
Both male and female fleas take in the bacillus pasteurella
205

pestis from infected rats during feeding
...
When this
bacterium is introduced into the skin, the lymph glands become inflammed
...
Frequently, the bacilli become established
in the victims blood
...

If the victim’s lungs become involved, it is referred to as pneumonic Plague
When the rat flea sucks the blood of man or a rat infected with plague,
the bacilli enter into its stomach and grow there into large numbers
...
The bacilli are deposited by the flea
on the skin along with the faeces
...

Control :
Destruction of rats and other rodents is an effective method
...
Application of 5% DDT is
recommended for spraying at the time of the spread of plague in all the areas
...
The human louse - Pediculus humanus:
Louse is a blood sucking ectoparasite of man
...

The human louse is a major vector for three important human diseases, relapsing fever, typhus and trench fever
...

5
...

Mosquitoes are cosmopolitan in distribution
...
Only
female mosquitoes are adapted to suck the blood of human beings and function as carrier of viral, protozoan and nematode diseases
...
This disease is caused by the nematode parasite, Wuchereria bancrofti
...
It is found in the lymphatic vessels and
lymph glands of man
...
The microfilariae normally circulate at night(10 to 2 am) in
the peripheral blood
...

Developmental changes take place in the body of the parasite
...
In severe infection the adults cause blocking of lymphatic system
which results in the enlargement of legs, arms, scrotum, and mammary glands
...

The Anopheles mosquito transmits plasmodium, a causative protozoan
for malaria (Refer : Plasmodium)
Another type of mosquito, Aedes transmits yellow fever through a
virus
...
2
...
6
...
2
...
These protective devices ranges from the simple
stinging cells of Physalia to the massive poison glands of the snakes
...
A few of the important poisonous
organisms are mentioned here
...
They are notorious for the painful
sting they can inflict on unsuspecting swimmers who accidently brush against
them
...
Their
powerful stings cause painful local inflammation and can even be fatal
...

In scorpion the sting is attached to the posterior part of the last
segment
...
The venom is produced by a pair of oval glands
...
A stabbing
motion is used in stinging
...

The venom of the scorpion Androctonus is equivalent in toxicity to cobra
venom
...
Anti
venoms are available for these species
...
They live in soil and
humus and beneath stones
...
They have a large
pair of poison claws sometimes called maxillipeds
...
The venom although painful is not sufficiently toxic to be lethal
to man even to small children
...
gigantea has been known to cause
human death
...
6
...
3
...
It is a pointed structure provided with
minute hooks or barbs at its free end
...
Hence a bee can sting only once
...

Hence it can sting again
...
The wasp’s poison is a histamine
...

Poisonous fishes
More than 700 species of fishes have poison glands
...
One kind of venom is produced by specialized glands which
may occur in various parts of the body
...

There are several poisonous cartilaginous fishes
...
In the
sting ray(Trygon), the poison glands lie along a lateral groove on each side
of the spine on its tail
...

The large Barracuda of Cuba and other tropical islands have
poisonous flesh, which when eaten cause pain in joints and extremities,
nausea, vomiting and general trembling
...
6
...
4
...
Its ovaries, intestine, kidneys, skin and eyes contain a
neurotoxin called Tetradoxin
...
It is several times
deadlier than cyanide
...
6
...
5
...
These can be distinguisted from the non poisonous by the
tail, the arrangement and size of scales, plates and shields found over the
body
...
When provoked it raises its
head and expand the skin of the neck region in the form of a characteristic
hood
...
Such cobras are called two
ringed or spectacled forms
...
These are known as the one ringed or monocled variety
...
In still others there is no mark on the hood
...
They are Naja naja (Indian cobra) and
Ophiophagus hannah (king cobra)
...
There are two common Indian kraits
...
fasciatus)
...
Some have a distinct pit on the sides
of the head between the nostril and the eye in the region called ‘lore’
...
The other one is the pitless viper
...

The vipers have movable upper jaw, so that the fangs when not in use can be
folded backwards
...
It produces a loud hissing sound by expelling air through nostrils
...

Pit viper - Trimeresurus sp
Sea Snakes : Sea snakes can always be distinguished from other snakes by
their laterally compressed tails
...
All
sea snakes are highly poisonous
...
Hydrophis sp Enhydrina sp
Poison Apparatus of a Snake
The poisonous snake possesses a poison apparatus comprising of a
pair of poison glands, a pair of poison ducts and a pair of fangs
...

They are specialized salivary glands
...
A fang is meant for injecting the venom into the body
of the prey
...

fang
poison duct
poison gland

tongue
Fig
...
2
...
Snake jaw showing fangs and poison glands

211

Canalised teeth of
russell’s viper

Gutter teeth of poisonous snake
non-poisonous snakes
cobra
Fig
...
2
...
Fangs of snakes and marks left by the bite of poisonous and
non-poisonous snakes

Biting mechanism in Cobra
Cobra is not an aggressive snake
...
When the snake attacks, the mouth opens by lowering the lower jaw
...
When
the mouth is closed the poison glands are pressed
...
This whole process takes
place in no time
...
One type acts mainly on the
nervous system (neurotoxic)
...
The
other type is haemolytic
...


6
...
3 Fouling Organisms
Several aquatic organisms cause damages to submerged surfaces
...
Marine sedantary organisms may affect piles, floats, wooden dry docks
and boats
...
Most of these organisms are
distributed all over the world through the agency of ships
...
The efficiency of underwater sound equipments fitted on to commercial and naval vessels is also seriously affeceted as result of the accumulation
of fouling organisms
...
Thus the
problem of fouling organims is serious
...
The most important of which is recognised to be the
formation of the primary film
...
The thin filaments of algae
may afford foothold on the substratum for the larvae to settle
...

Members of the fouling community
The most important members of the fouling community include algae
and representatives from almost all the invertebrate groups and the tunicata
...
They settle
heavily, especially in the pipe systems carrying seawater and obstruct the flow
of water
...
There are over 100 species of barnacles as foulers
...


Tunicate

Fig
...
2
...
Common foulers

213

1
...

2
...

3
...


6
...
4 Pests
Any animal which becomes a source of trouble or loss to human is
called a pest
...
An insect is usually called as a pest when it causes appreciable damage
and loss to the crops or other belongings
...
The insects damaging standing crops cereals, fruits and
other plant products of commercial importance are designated as crop pests
...
Insects
causing damage to household articles are called the household pests
...
6
...
9
...
Pest of Cotton
a
...

b
...

c
...
insulana
These two species are the most important pests of cotton in India
causing heavy losses to the crop every year
...

The caterpillars of Earias
...
The attacked shoots
wither, droop and ultimately die
...

Avoid growing lady’s finger during the offseason in the vicinity of the cotton
fields
...

II
...
Rice stem borer - Tryporyza incertulas
This pest bores into the stems of the young mature stages of paddy
...
Rice bug - Leptocorisa acuta
It is the most important pest of paddy in India
...

The adults and nymphs feed on the milky juice of the forming grains which as
a consequence become chaff
...
As the bugs feed and breed on various types of
grasses, removal of such grasses from the fields will help in reducing the
population
...
Among the insecticides BHC and malathion as dusts
and carbaryl and methyl parathion as sprays just before flowering of the plants
are effective
...
Pest of Sugarcane
a
...

This pest sucks the cell sap of leaves
...
Sugarcane root borer - Emmalocera depressella
...

c
...

This pest causes damage to the shoot
...
Sugarcane top shoot borer - Scirpophaga nivella
It is one of the most destructive pests of sugarcane
...
The damage by the borer actually starts from the mid-rib of the top leaves
into which it bores and makes tiny holes
...
The
quality of the juice is also affected
...
Mechanical methods include the collection and destruction of egg masses and affected top shoots and sowing of resistant varieties
...
05 % monocrotophos or 0
...

IV
...

a
...

This pest causes damage to the leaves, flowers and buds of younger plants
...
Cabbage butterfly - Pieris brassicae
...

c
...

This pest causes damage to the leaves of the brinjal, potato and tomatoes
...
Brinjal shoot and fruit borer - Leucinodes orbonalis
...
The pest starts damaging the brinjal plant a few weeks after its
transplantation
...
When the petioles of the leaves are bored into by the larva the
216

leaves wither and drop
...
Upto 70 % loss of crop is caused by this pest
...
Insecticides such as carbaryl, endosulfan, Lindane
and diazinon, when applied at regular intervals give relief from heavy infestation
...
Pest of Coconut palm
Rhinoceros beetle - Oryctes rhinoceros
...
The adult causes infestation by feeding the young leaf fronds
...
The infestation is marked by a number of holes on the fronds, when
they open out
...

Control : The beetles should be destroyed by inserting specially designed hooked
rod
...
01% aldrin
...
Pests of Stored grains

Rice weevil

Khapra beetle

Pulse beetle

Fig
...
2
...
Pests of stored grains

a
...
It is
worldwide in distribution
...
The grains are hollowed and the weight
is reduced
...

Hence dry storage of grains can aviod infestation by the pest
...
Fumigation of infested
grains with methyl bromide is also effective and kills all stages of pest including
eggs
...
Khapra beetle - Trogoderma granarium
Khapra beetle is a very serious pest of wheat and other stored grains all
over India
...
The
grubs attack the germ portion of the grain
...

Control : Stocks of grains should be stored in thoroughly clean and insect-free
stores which are regularly aerated
...

c
...
It affects both
in fields and in stores
...
The larvae bore into the pulses and grains
...
The damaged grains are unfit for human consumption
...
Fumigation with methyl bromide in the godown is very effective but proper care must be
taken because of the high toxicity of this compound
...
Pests of household goods

Termite
Silver fish

Fig
...
2
...
Pests of household goods

218

a
...
The food of termites consists primarily of wood (cellulose)
...
They destroy wood work, furnitures,
buildings, fences and other wooden structures that come into contact with the soil
...
About 40 species of termites are injurious to economic plants such
as wheat, barley, maize, gram, sugarcane, groundnut, several vegetables, fruit trees
and coconut in India
...
For termite
control, insecticides should be applied to the soil
...
5
% aldrin and 0
...
5 % pentachlorophenol is good for wood preservation
...

b
...
It is commonly found living in moist warm
places and among old books
...
It infests starched clothes, rayon
fabrics, book labels or bindings where glue has been used
...
Books should be exposed
to sunlight frequently
...

Self - Evaluation
Part I

Choose the correct answer
...
Reef forming corals normally grow in
(a) cold waters
(b) deep seas
(c) shallow, tropical seas
(d) polluted and muddy waters
2
...
Earthworm commonly employed in Indian vermiculture is
(a) Lampito mauritii
(b) Apis indica
(c) Penaeus indicus
(d) Pinctada fucata

219

4
...
The honey bee used commonly in bee-keeping industry is
(a) Apis dorsata
(b) Apis florea
(c) Apis indica
(d) all the above
6
...
The predatory insects are said to be
(a) entomophagous
(b) larvivorous
(c) parasitic
(d) pests
8
...
The most common freshwater prawn used in aquaculture is
(a) Macrobrachium sp
(b) Metapenaeus sp
(c) Penaeus sp
(d) Panulirus sp
10
...
The fish Stromateus argenteus is popularly called as
(a) guppy
(b) pomfret
(c) gold fish
(d) angel fish
12
...
Which country was economically benefitted by marketing bird excreta
(a) USA
(b) Peru
(c) Australia
(d) West Indies
14
...
Nandankanan Biological park is situated in
(a) Delhi
(b) Orissa
(c) Bihar
(d) Assam
16
...
Which is the best time to have blood test for filariasis
(a) morning
(b) evening
(c) noon
(d) mid-night
18
...
Ophiophagus hannah refers to
(a) Indian cobra
(b) King cobra
(c) Russell’s viper
(d) Sea snake
20
...
What is a fringing reef ?
2
...

3
...
Name any two edible crabs
...
Provide the names of one live bearer and one egg layer from among the ornamental fishes
...
Provide the names of zoos in the states of Tamilnadu and Andhra Pradesh(one
each)
...
Name the two types of venom released by poisonous snakes
...
Provide atleast one major role of CMFRI
...
Name any two cultivable animals
...
What is Corallum rubrum ?

221

Part III
Answer briefly
1
...

2
...

3
...

4
...

5
...

6
...
Give an account on fouling organism
...
Draw and label the poison apparatus in a snake
...

1
...

2
...

3
...

4
...

Identify and name

222

7
...
1
...
The plants and animals show remarkable biodiversity
...

This vastness has always made people wonder about the origin of life and
diversity
...
However the theory of origin of life is still a matter of speculation
...

1
...
The
support or acceptance of this theory is mostly due to faith rather than experimental or scientific evidences
...

2
...
The resistant spores that lead to life on earth are named as ‘cosmozoa’
...
Under favourable conditions they evolved
and produced all forms of life on earth
...

3
...
An earlier version of this theory was spontaneous generation or the origin of life without apparent cause
...

Thales (624-548 BC) suggested that oceanic water was the mother
from which all living forms originated
...
Aristotle (384-322 BC) proposed that living forms
are animated forms of non-living matter
...
He further stated that the vital forces operate constantly and improve the living world
...
For the first time he proposed through
experiments, that life could arise only from pre-existing living things
...
Soon the meat in the open flasks was full of
maggots
...
Even after many days no
worm appeared in the closed and sealed flask
...

4
...

According to this theory the universe originated in a ‘big bang’
...
According to this theory as a young star increases in density, it gets heated up due to increasing pressure
...

It is believed that our sun was formed in this way
...
A
...
Oparin’s theory
Alexander I
...
He
advanced a new theory regarding origin of life
...
According to Oparin conditions on Earth today are
no longer suitable to the production of life from non living matter
...
The earth during that period had many simple chemical compounds
...
The origin of complex
organic molecules made the origin of life easier
...
J
...
S
...
He was the first to propose that life
originated on earth, when the atmosphere was devoid of O2 gas
...
The ozone layer protects
earth by preventing the entry of harmful cosmic radiations
...
Hence
ultra violet rays were freely entering earth’s atmosphere
...
These molecules gradually accumulated in the
oceans as a dilute ‘soup’
...
Urey - Miller hypothesis
tungsten electrodes
nitrogen, ammonia, methane

condenser

water vapour
boiling water

condensate having amino acids

Fig
...
1
...
S scientists Harold Urey and Stanley Miller in 1950’s proposed and
attempted to prove that amino acids can be synthesised outside living
systems
...

This trial yielded aldehydes, amino acids and carboxylic acids
...
These
chemical incidents could have paved the way for the origin of a cellular
organisation
...
Coacervation theory
Coacervates were considered to represent the protocell model
...
He reported that coacervates are readily
formed from aqueous suspension of proteins, polysaccharides and nucleic acids
...
Such systems were considered the forerunner of living
cells
...
2
...
8 billion (3800 million) years old
...
According to Geologists and Geophysicists our planet earth is 4
...

In this ancient time scale evidenes showed that the first life originated
2
...
Hence from the formative stage for nearly
2,200 billion years there was no life on earth
...
Evidences show that during this era the earth was a hot sphere
...
It resulted in solidification and formation of rocks and rocky terrain
...
These transformations provided a
suitable condition for the origin of the first life
...
Changes happened in the structure, organisation and living methods of
organisms, depending on natural surroundings and changes in natural surroundings
...
The water masses
were fully exploited
...

The Geological time succeeding Azoic Era, was dramatic and rich in
life
...
These were significant periods in
earth’s history
...
It ranged
from 600 to 210 million years ago
...
This era saw the origin and adaptive radiation of sponges, starfishes,
snails, insects, crabs, and terrestialised amphibians and reptiles
...
This era ranged from 65 to 210 million years ago
...
During this era, among animals the reptiles came to prominence
...
Further this
era saw the origin and development of birds and reptiles
...
This era is characterised by rapid evolutionary changes in
mammals
...


Geological time scale
A geological calendar has been formulated by assessing the age of
rocks and rock sediments
...
years ago

“Cradle of anicent life”
...
years ago

“Golden age of reptiles”
...
years ago

“Age of mammals”
...
Each division in the
geological calender is clearly identified and demarcated
...
The influence of
geological and climatic changes on the life and the evolution of the living organism had been well analysed
...
years ago
7 - 2 m
...
years ago

TERTIARY - Oligocene 38 - 26 m
...
years ago
TERTIARY - Palaeocene 65 - 54 m
...
years ago
160 - 130 m
...
years ago

PERMIAN
PENNSYLVANIAN
MISSISSIPPIAN

235 - 210 m
...
years ago
275 - 255 m
...
years ago

SILURIAN
ORDOVICIAN

350 - 315 m
...
years ago

CAMBRIAN

600 - 440 m
...
years ago

228

Human evolution
Rodents were successful
Mammals increased
Priaries were formed
Horses evolved
...

Dinosours became extinct
Birds originated
Modern bony fishes
...

Mammals originated
...

Land living insects
...

Land living insects,
Forests
...
Fernsand
cycas
...

Thallophytes,
Arthopods,Molluscs,
Echinoderms
...


I
...
Further this era saw the origin and the radiation of several groups
of animals and plants that remained as the forefathers for the modern groups
...

1
...

During precambiran time simple algae, protozoans, poriferans, annelids, were
well established
...
During cambrian among plants
thallophytes were well establised
...

(Chlorophyceae, Rhodophyceae etc
...
The fossils of such organism were
obtained from several places
...
Ordovician period :- (440 to 350 million years ago)

Fig
...
2
...
Among plants the semi terrestrial bryophytes were getting established
...
These
were the now extinct agnatha
...
The origin of early
vertebrates was the major event that happened in the evolution of animals
...

3
...
These plants possesed
conducting tissues
...
Among invertebrates except for
insects all others flourised
...
Several coral islands were
formed
...
The fishes developed scales and paried fins,
for the first time jaws originated in fishes
...


229

Pteraspis (Ostracoderm)

Coccostens (Placoderm)
Fig
...
2
...


4
...
During this period land
living plants were more successful
...
(non-flowering plants)
...
They diversified by adapting themselves to live in various
aquatic ecosystems
...
Due to these reasons this period is called as the Age of fishes
...
Mississippian Period :- (275 to 255 million years ago)

Fig
...
2
...
There were massive
upraising of land in several places
...
Huge water bodies were broken into smaller lakes
...
Caledonian
revolution)
...

Lungs evolved for the purpose of living temporaily on land
...
Such practises encouraged the origin of the
230

amphibians
...

6
...
There
were huge forests of ferns and cycas
...
Today’s coal and petroleum are obtained
from such resources only
...

7
...
This period was marked by
extinctions of several older groups of animals and plants
...
Some of the
amphibians dramatically laid land eggs (cleidoic eggs)
...
These are
considered as inter-connecting links between amphibians and reptiles
...
Mesozoic Era :This middle period in the history of life was marked by the
prominence of land living forms
...
They increased in size and in number
...

1
...
Fossil evidences show that aquatic and
flying reptiles thrived during this time
...

2
...
They diversified into carnivorus and herbivorus forms
...
The earlist bird thus originated is known as the Archeopteryx
...
From a more
common poikilothermic condition through feathers the birds became homeothermic
...


231

Brontosaurus

Tyrannosourus

Pterosaurus

Archaeopteryx

Fig
...
2
...
The fossils of such organisms are available in places like Ariyaloor, of Tamil Nadu, today
...
Several reasons are given for the extinction of the dinosaurs
...


III
...
7
...
5 Triceratops - a horned dinosaur

Plenty of fossil of organisms belonging to this era had been obtained
...
This era is
subdivided into Tertiary and Quarternary periods
...
Through fossils we can trace the origin and evolution of independent groups of animals, camels and man
...
Paleocene epoch :Modern placental mammals originated during this time
...
Eocene Epoch :Ungulates originated
...

3
...
Modern
mammalian families were established
...

4
...
America
...
These changes encouraged the evolution of fast
233

running herbivorus mammals and their predators
...

5
...
The rodents
became more successful
...

6
...
This epoch is
popularly called the ‘Ice age’
...
The melting of ice that happened 1,500 years
ago is considered as the last stage of this epoch
...


7
...
Fossils may be of entire organisms or a part
which got buried, a mould or cast, foot prints or imprints of a leaf on a stone
...
However these methods are purely accidental
...

1
...
In this method dead and buried
organisms turn into stones
...
While the soft parts disappear due to decaying, hard parts get preserved due to mineralisation
...

2
...
Several such plant
fossils had been obtained
...
Preservation of foot prints :- Moving animals on soft mud can leave foot
prints
...
A study of such imprints can provide clues regarding the body form and
characteristics of the extinct animal
...
Moulds and casts :- Fossilized moulds are found in volcanic ashes
...
They provide details
about the exact physical features of the animal
...
Fossilization in resins and amber :Normally, insects get entangled in soft sticky secretions of trees called
resin
...
These fossils can even reveal the
colour of the organism
...
Preservation in ice :- Entire animals can get frozen and may be preserved in ice
...

Fossils of woolly mammoth from Siberia are classical fossils of this nature
...
Dating of fossils :- The age of the fossils to a large extent can be assessed
accurately, using radioisotope method
...
Isotopes are atoms having slightly different atomic weights
...
g c 12
and c14
...
They undergo decay and release sub
atomic œ and ß particles till they become more stable
...
The half-life of many isotopes is
useful to assess the age of the rock accurately by measuring the ratio of
unstable : stable nuclides
...
c14 : c12 of the rock in which the fossil was
collected
...
Fossils tell us the full story of evolution
...

2
...
g
...

3
...

4
...

5
...


Important fossils
Ichthyostega - interconnecting link between fishes and amphibians
...

Archaeopteryx - Ancestral form of birds
Dinosaurs - Extinct group of reptiles
...

235

7
...
Extinctions are of two types namely true extinctions and pseudo
extinction
...

Pseudo extinction may also be called as phyletic extinction or
phyletic transformation In this type a group may disappear leaving descendents with evolutionary modifications
...
Extinctions can happen for the taxonomic groups such as a
family or genus
...
Similar extinctions happened to trilobites
...
It happens due
to abrupt changes in evironmental conditions or other biological factors
...
From the fossil record
it becomes evident that extinctions have occured at regular intervals of time
...
Major groups of
herbivorous vertebrates are more susceptible than the carnivorous vertebrates
for extinction
...
VanValen(1973)
recorded a constancy in the rate of extinction in a number of groups
...
According to this law as every new
adaptation encourages the survival of a possessor it also decreases a fitness
of other related species of that area
...
(2) Any adaptive
advance in one species decreases the fitness of all other species
...
(3) Over specialistion to a specific
situation may cause extinction
...
Antlers
...
(5) An increase in the popu236

lation strength of herbivorus animals can cause rapid food shortage and cause
extinction for several inter-related groups
...
(7) A dust storm formed due to falling of
a meteorite is commonly mentioned as a cause for the disappearance of
dinosaurs
...
By the end of permian period of the
Paleozoic Era, nearly 60% of the varieties then existed, became extinct
...

However the extintion of animals and plants during our time is mostly
due to human interference
...
The realisation of a such a cause lead to starting
of several international voluntary agencies to monitor and control extinctions
...
W
...


Self Evaluation
Part - A
1
...
The proposal that living forms are animated forms of non-living matter was
provided by
a) Empedocles
b) Thales
c) Lamarck
d) Aristotle
3
...
Mesozoic era is commonly refered to as
a) age of mammals
b) age of fishes
c) golden age of reptiles
d) cradle of ancient life
5
...
The duration of cenozoic era was
a) 210 to 65m years ago
b) 65m year ago to till date
c) 600 to 440 m years ago
d) 210m year ago to till date
7
...
The earliest ancestor of horses were
a) Eohippus
b) Equus
c) Seymouria
d) Dinosaurs
9
...
Identify the early ancestor of horses
a) Dinosaurs
b) Seymouria
c) Archaeopteryx
d) Hyracotherium
Part - B
1
...
B
...
Why do we call the palaeozoic era as the cradle of ancient life
...
What was Archceopteryx ?
4
...
What is dating of fossils ?
6
...
What is Mac Author’s law ?
8
...
What is abiogenesis ?
2
...

3
...
Give an account of the significant events of the Palaeozoic era
...
Give an account of various epochs included in Cenozoic era
...
Give an account of the Mesozoic era
...
What is mass extinetion ? Provide the causes for such extinctions
...
Write an essay on fossils and methods of fossilization
...
Manual of Zoology Vol
...
Part
...
(Invertebrata), M
...
N
...

2
...
I
...
II
...
Ekambaranatha
Ayyar and T
...
Ananthakrishnan, Reprint 2003
...
Manual of Zoology Vol
...
Chordata M
...
N
...
S
...
Ltd
...

4
...
L
...
S
...
Reprint 2003
...
Chand
...

5
...
D
...
N
...
Chand and
Company Ltd, Ram nagar, New Delhi - 110 055
...
Concept of Cell Biology P
...
Verma and V
...
Agarwal 1/e Reprint
2002
...
Chand and Company Ltd, Ram nagar,
New Delhi - 110 055
...
Cell Biology

N
...
1999
...


8
...
S
...
K
...
S
...

9
...
S
...
2002
...
Chandand Company Ltd, Ram nagar,
New Delhi - 110 055
...
Chordate Embryology P
...
Verma and V
...
Agarwal Reprint 2003
...
Chand and Company Ltd, Ram nagar,
New Delhi - 110 055
...
A Text book of Embryology N
...
1999
...

12
...
S
...
Rastogi
Publications, Shivaji Rd, Meerut - 250 002
...
A Hand Book on Economic Zoology Jawaid Ahsan and Subhas Prasad
Sinha
...
S
...

14
...
S
...
K
...

S
...

15
...
Arumugam 9/e
...
Saras Publication
A R P Camp Rd, Peria vilai, Kottar,
Nagercoil - 629 002
...
pcisys
...
html
http://www
...
edu/~riwin/b120lab
...
com/uci/lessons 98/Invertebrates
...
student
...
org/zoology/chordates
...
utmb
...
yahoo
...
bartleby
...
mhhe

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