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ZOOLOGY
HIGHER SECONDARY - FIRST YEAR

Revised based on the recommendation of the
Textbook Development Committee

A Publication under
Government of Tamilnadu
Distribution of Free Textbook Programme
(NOT FOR SALE)

Untouchability is a sin
Untouchability is a crime
Untouchability is inhuman

TAMIL NADU
TEXTBOOK CORPORATION
College Road, Chennai - 600 006
...
T
...
of Zoology
Govt
...

Reviewers
Dr
...
Mony
Reader in Zoology
R
...
Vivekananda College
Mylapore
Chennai - 600 004
...
D
...
of Zoology
Loyola College, Nungambakkam
Chennai - 600 034
...
Anne Freeda Chandran
P
...
T
...
Sec
...


Tmt
...
M
...
G
...
in Zoology
Govt
...
School
Ashok Nagar,Chennai - 600 083
...
T
...
G
...
in Zoology
Govt
...
School
Choolaimedu
Chennai - 600 094
...

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-Radio therapy-Chemotherapy
...


Unit IV : Genetics
Introduction - Multiple alleles - Quantitative inheritance - Sex
determination - Sex linked inheritance - Pleiotropy-Hardy Weinberg lawPopulation genetics
...

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

Unit VII : Origin of life
Theories - Geological time scale - Fossils - Extinct animals - Mass
extinction-Evidences for evolution-Comparative anatomy-EmbryologyPhysiology-Vestigeal organs-Geographical distribution
...


IV

Prepared slides - observation - drawing and writing notes on

1
...
Paramoecium - entire, Paramoecium - conjugation
3
...
Tapeworm - Scolex
5
...
Amphioxus - entire
7
...
Shark - Placoid scales
V

Museum specimens

Simple sponge, Corals, Tapeworm - entire, Ascaris - entire (male and
female), Earthworm - entire, Prawn - entire, Cockroach - Dorsal and ventral
views, Apple snail, Sepia, Star fish, Sea urchin, Amphioxus, Shark, A teleost
fish, Frog, Calotes, A snake, Pigeon, Quill feather, Rat
VI

Demonstration only

1
...
Circulation of Blood in the wing of a live cockroach
...
Frog - Buccal cavity, viscera and Digestive system
...
Upper and lower jaw with dentition
2
...


BIODIVERSITY

1

2
...


HUMAN ANATOMY

104

4
...


DEVELOPMENTAL BIOLOGY

201

6
...


ORIGIN OF LIFE

268

vii

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

FIVE KINGDOMS

Kingdom 1

Kingdom 2

Kingdom 3

Kingdom 4

Kingdom 5

Monera

Protoctista

Fungi

Plantae

Animalia

Outline Classification of Animal Kingdom
ANIMALIA

PROTOZOA
Now kingdom : Protoctista
Eg : Ameoba

METAZOA

PARAZOA

EUMETAZOA

PHY : PORIFERA

Eg : Sponges
PHY : COELENTERATA

Eg :

Hydra

RADIATA
DIPLOBLASTIC

BILATERIA
TRIPLOBLASTIC

ACOELOMATA

PSEUDOCOELOMATA

PHY : PLATYHELMINTHES

PHY : ASCHELMINTHES

Eg : Tapeworm

EUCOELOMATA

(or)
NEMATODA

Eg : Ascaris

PHY : ANNELIDA PHY : ARTHROPODA PHY : MOLLUSCA PHY : ECHINODERMATA PHY : CHORDATA

Eg : Earthworm

Eg : Cockroach

Eg : Pila

11

Eg : Starfish

Eg : Rat

PHYLUM - CHORDATA
SUB-PHYLUM
SUB-PHYLUM
SUB-PHYLUM
SUB-PHYLUM
HEMICHORDATA CEPHALOCHORDATA UROCHORDATA VERTEBRATA
Eg : Balanoglossus Eg : Amphioxus
Eg : Ascidian
Eg : Fish

CLASS

1
...
AMPHIBIA
Eg : FROG - RANA

3
...
AVES
Eg : PIGEON - COLUMBA
5
...
Monotremata (Prototheria)
Eg
...
Marsupalia (Metatheria)
Eg
...
Placentalia (Eutheria)
Eg
...
Man

12

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

13

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)
...


14

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
...


15

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

19

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
...


20

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
...


22

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

24

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
...


25

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

28

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
...


29

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
Invertebrates
Scientific Names
Earthworm (k©òG)

Lampito mauritii

Cockroach (fu¥gh‹ ó¢Á)

Periplaneta americana

House fly (<¡fŸ)

Musca nebula

Locust (bt£L¡»ë)

Schistocera gregaria

Bed bug (_£il¥ ó¢Á)

Cimex hemipterus

Leaf insect (Ïiy¥ó¢Á)

Phyllium sps

Stick insect (F¢Á¥ó¢Á)

Carausius sps

Water-scorpion (Ú®¤njŸ)

Nepa sps

Butterfly (t©z¤J¥ ó¢Á)

Pieris sps

Rat flea (vè bjŸS¥ó¢Á)

Xenopsylla cheopis

Scorpion (njŸ)

Palamnaeus swammerdami

King crab (uh# e©L)

Limulus sps

Spider (ÁyªÂ¥ó¢Á)

Aranea sps

Apple snail (M¥ÃŸ e¤ij)

Pila globosa

Freshwater mussel (e‹Ü® e¤ij)

Lamellidens marginalis

Star fish (e£r¤Âu Û‹)

Asterias rubens

Vertebrates
Angel fish (VŠrš Û‹)

Pterophyllum scalare

Guppy (f¥Ã Û‹)

Poecilia reticulata

32

Frog (jtis)

Rana hexadactyla

Garden lizard (Xzh‹)

Calotoes versicolor

Cobra (ešy gh«ò)

Naja naja

Peacock (kæš)

Pavo cristatus

Crow (fhf«)

Corvus splendens

Sparrow (FUé)

Passer domesticus

Parrot (ȑ)

Psittacula Krameri

Rat (vè)

Rattus rattus

Dog (ehŒ)

Canis familiaris

Cat (óid)

Felis domesticus

Tiger (òè)

Panthera tigris

Lion (Á§f«)

Panthera leo

Elephant (MÁa ahid)

Elephas maximus

Man (kåj‹)

Homo sapiens

Monkey (Fu§F)

Macaca radiata

Mongoose (Ñç¥ÃŸis)

Herpestes edwardsii

Bear (fuo)

Ursus arctos

Fruit bat (gHªÂ‹å btsthš)

Cynopterus sphinx

Donkey (fGij)

Equus hemionus

Rhinoceros (fh©lhäUf«)

Rhinoceros unicornis

Spotted deer (òŸë kh‹)

Axis axis

Man (kåj‹)

Homo sapiens

33

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)

34

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

oocyst
spore
formation

zygote
marcrogamete
stomach
sporozoisalivary gland food channel

early
schizont

salivary duct
Endo-erythrocytic cycle

merozoite
livercell

rupture of
signet ring
RBC

Schizogony

RBC
crypto-merozoites
crypto-schizont

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

35

Life history of Plasmodium (the malarial parasite)
Life cycle in Man (Schizogony)
Mosquito
In liver :- Pre or
Exoerythrocytic Cycle

Sporozoites
Cryptozoites
Cryptomerozoites

In RBC :- Erythrocytic or

Trophozoites

Endo-erythrocytic cycle or

In blood plasma

Schizonts

Cycle of golgi

(febrile attacks)

Merozoites

Gametocytes(in RBC)
Life cycle in Female anopheles mosquito (Sporogony) or Cycle of Ross
Inside the gut

Gametocytes (in RBC)
Gametes [male(micro)
and female (macro)]
Zygote
Ookinete

In the wall of the gut
Oocyst
Sporozoites
Man
36

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
...
No

Species of Plasmodium

Type of fever

1
...


P
...


P
...


P
...
No

Stage

Occurrence

1
...


Cryptozoite

Liver (man)

3
...


Amoebula stage

RBCs (man)

5
...


Merozoite

RBCs (man)

7
...


Microgamete

Stomach of female
anopheles mosquito

9
...

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
...


40

(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)
...


42

(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

47

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

48

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
...
Amphioxus
Phylum
: Chordata
Sub Phylum : Cephalochordata
Type
: Amphioxus
This group comprises an assemblage of small fish like
marine organisms belonging to two genera, Branchiostoma and
Asymmetron
...
Thus, it may be considered as a
49

blue print of the phylum
...

Distribution :Amphioxus is a marine organism having an almost world wide
distribution
...

Habit and Habitat :Amphioxus is usually found buried in the sand with the fore or
anterior end projecting outside
...
Occasionally, it emerges out of the burrow and swims about
by the sinuous movements of the body
...

External features :notochord

myotome

dorsal fin rays
nerve cord

tail fin

anus

ventral finray
atriopore

liver

gonad

pharynx
gill slits

buccal cirri

Fig
...
3
...
5 to 3 cm long
...
It lacks a head
...
The dorsal fin runs along the
whole length of the mid dorsal line
...
The dorsal and ventral fins are supported
by fin rays
...
It is
because the two lateral sides project down as flaps called metapleural folds
...
The metapleural folds are continuous anteriorly with the oral hood
...
The vestibule is surrounded
by a membrane called oral hood
...

The mouth is situated at the bottom of the vestibule in the middle of a
membrane called velum
...
On the inner side of the oral hood, the
epithelial lining is thrown into ciliated finger-shaped processes
...
On the roof of the oral hood there is a ciliated pit called the Hatschek’s
pit
...

Atrium :In Amphioxus, the gill slits instead of opening directly to the
outside, open into a special cavity called the atrium
...
It is lined by ectoderm and is
enclosed by the lateral extensions of the body wall
...
The cavity encroaches into the bodycavity almost completely replacing the coelom
...
The atrium
gives protection to the gills, preventing them from being choked up with sand
...
It is composed of
outer epidermis and inner dermis
...
The dermis consists of an outer layer of connective
tissue (cutis) containing fibres and an inner thick layer of matrix (sub cutis)
invaded by few fibres, blood channels and nerve endings
...
The number of myotomes may vary from 60
or more
...

51

Coelom :- Coelom of amphioxus is distorted and restricted by the immense
size of the atrium
...
1
...
10 (b) Amphioxus V
...
of body wall

Skeleton :- The skeleton consists of a peculiar tissue called notochordal
tissue and of gelatinous material
...
Other skeletal structures are connected with the oral hood, the
fins and Pharynx
...
It leads
into a large laterally compressed chamber, the Pharynx which occupies the
most anterior part of the body cavity
...
From the
pharynx the narrow tubular midgut or intestine extends backwards to the
anus
...

Running along the inner wall of the pharynx both on the dorsal and
ventral middle lines are two grooves lined with cilia ; the dorsal groove is the
hyperbranchial groove and ventral groove is the endo style
...
The ventral groove is composed of four tracts
of mucous glands separated by tracts of ciliated cells
...
Anteriorly the endo style
and the hyperbranchial grooves are connected by two ciliated tracts, which
52

dorsal finray
myotome
nerve cord
notocord
dorsal aorta
epipharyngeal groove
dorsal coelom
pharynx
gonad
liver
metapleural fold
endostyle
Fig
...
3
...
S
...
1
...
10 (d) Amphioxus - T
...
through the intestinal region

encircle the pharynx just behind the mouth
...
The inner wall of the pharynx is lined with cilia
...
While feeding, a continuous current of water enters
the mouth and expelled out through atriopore via pharynx and atrium
...
The velar tentacles behind the mouth fold across
and strain off the sand particles
...
The cilia drive them along the gill
bars and peripharyngeal bands into hyper branchial groove and thence to the
intestine
...
Digestive enzymes are
secreted in the midgut diverticulum and poured into the midgut
...

epipharyngeal groove
pharyngeal cavity
gill slit
gill bar
atrial cilia
atrium
endostyle
metapleural folds
Fig
...
3
...
The oxygen diffuses into the blood flowing
in the channels of gill bars and the carbon di oxide from the blood diffuses
into the running water
...
The blood is
colourless
...
There is a median
contractile vessel (ventral aorta) in the ventral wall of the pharynx below
the endostyle
...
The ventral aorta
sends paired afferent branchial vessels into the primary gill bars
...

The lateral dorsal aortae unite behind the pharynx forming a median
dorsal aorta which runs behind and gives branches and breaks up into
capillaries in the intestine
...
1
...
10 (f) Amphioxus - Diagram of the vascular system

region of the body is collected by a median subintestinal vessel, which lies
below the intestine
...
From the liver the
blood is collected by the hepatic vein which joins the ventral aorta
...
These are connected with
the ventral aorta by the cuvierian ducts
...

solenocytes
horizontal limb of nephridium
external opening of nephridium
vertical limb of nephridium

coelomic space in primary bar
secondary gill bar
primary gill bar
Fig
...
3
...
Each nephridium is a closed, bent tube
...
The vertical limb lies in the
coelomic canal of the primary gill bar
...
The horizontal limb
projects into the dorsal coelom
...
Both limbs of the nephridia are provided with groups of
flame cells or solenocytes
...

Each solenocyte is a hollow cell with a flagellum hanging down from the wall
...
The nitrogenous waste matter is collected by the solenocytes from
the blood as well as coelomic fluid and is passed on to the body of the
nephridium by the flagella
...
It finally
goes through atriopore
...
It
extends from the anterior to the posterior end of the body
...
A small longitudinal cleft, the dorsal fissure
extends throughout the length of the nerve cord
...

Reproductive system :- In amphioxus the two sexes are separate, but there
is no sexual dimorphism
...
These are simple hollow sacs and are mesodermal in origin
...
The gonads bulge conspicuously into the atrial
cavity
...

Fertilization and development take place in sea water
...
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
...


57

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

59

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

61

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
...

Since the heart pumps blood with force into the arteries, the vessels have
slightly muscular and strong walls
...
The pulmonary artery originates
from the right ventricle
...
As this artery leaves the heart, it divides into right and left
pulmonary arteries carrying blood to right and left lungs
...
In birds the left
aortic arch is absent
...

The left ventricle pumps oxygenated blood
...

64

The systemic artery forms right and left innominate arteries
...
The
subclavian arteries inturn divide into brachial and pectoral arteries
...

The carotid arteries carry blood to the head region
...
The dorsal aorta is a major artery supplying blood to the
abdominal organs and the posterior regions of the body
...
The coeliaco-mesenteric artery and anterior mesenteric artery these arteries carry blood to various regions of the alimentary canal and
certain visceral organs
...
Renal arteries - carry blood to the kidneys
...
Femoral arteries (2) - supply pure blood to pelvic muscles and external
thigh region
...
Sciatic arteries (2) - supply pure blood to internal thigh region
...
Iliac arteries (2) - supply blood to hip region
...
Posterior mesenteric artery - supplies blood to the most
posterior visceral organs
...
Caudal artery - carries blood to the tail region
...
Finally these veins take the blood to the right
auricle through the two precaval and a single postcaval veins
...

65

From the tail region the blood is drained by the caudal vein
...
Each portal vein runs through the kidney and
jugular vein
brachial vein
pectoral vein
precaval vein
post caval vein
hepatic vein
epigastric vein

hepatic veins

iliac vein

femoral vein
sciatic vein
renal portal vein
internal iliac vein

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

joins the femoral vein
...
It also
receives a pair of sciatic veins draining blood from legs
...

The precaval veins (2) are formed by the jugular and brachial veins
from the neck shoulder and head regions
...
The
cerebral hemispheres are distinct
...
The
olfactory lobes are very small and they do not contain cavities
...
The diencephalon has the pineal body dorsally and
infundibulum and pituitary body ventrally
...

The medulla oblongata instead of being continued backwards as in other
tetrapods, descends almost vertically from the cerebellum
optic lobe
cerebellum

olfactory lobe
cerebral hemisphere
cerebellum
optic lobe
flocculus

Dorsal view

medulla oblongata
optic chiasma

Lateral view

medulla
oblongata

Fig
...
3
...
Pigeon - Brain

Sense organ :In pigeon the olfactory sense is poor
...
The
tympanum is slightly sunken from the surface of the skin
...
1
...
20
...
During flight the eyes and their shape are protected by unique sclerotic plates of the outer eye layer
...
Inside the eye, a vascular pigmented process projects
into the vitreous body
...
It arises from the point of
entry of the optic nerve into the eye ball
...


Urinogenital system :The excretory organs are a pair of kidneys
...
They open separately into the urodaeum of the cloaca through
two different ureters
...
The urine is excreted in
the form of uric acid, a semi solid white mass discharged along with faeces
through the cloacal aperture
...
1
...
21
...
From each testis, a duct, the
vasdeferens, passes back and opens into the cloaca
...
There is no copulatory
organ
...
The right ovary disappears
during development
...


68

Unit - 1
Part I
Choose the right answer :1
...
The introduction of phylogeny in taxonomy was made by
a) Cuvier

b) Lamarck

c) Charles Darwin

d) Linnaeus

3
...

(a) Cuvier

(b) Michael Adamson

(c) Lamarck

(d) Charles Darwin

4
...


6
...
Five Kingdom concept does not include
a) fungi

b) viruses

c) flowering plants

d) bacteria

8
...
Which among the following is considered ‘a blood fluke’
a) Schistostoma

b) Taenia solium

c) Fasciola

d) Ascaris

69

10
...
Metameric Segmentation is seen in
(a) Protozoans

(b) Arthropods

(c) Annelids

(d) Mollusca

12
...
The characteristic feature of echinoderms is the possession of
a) compound eye

b) absence of coelom

c) diploblastic condition

d) water vascular system

14
...
Acrania refers to
a) fishes

b) birds

c) chordates

d) prochordates

16
...
Viviparous animals are
(a) Fishes
(c) Aves

(b) Mammals
(d) Reptiles

18
...
Which among the following is considered as a defeated group
a) amphibians

b) reptiles

c) mammals

d) fishes

70

20
...
Which among the following is not a character of mammals
a) diaphragm

b) right aortic arch

c) mammary glands

d) corpus collosum

22
...
In earthworm the clitellum is present in segments
a) 5 to 10

b) 14 to 17

c) 13 to 18

d) 20 to 25

24
...
The chlorogogen cells on the wall of the intestine in earthworm is meant for
a) digestion

b) circulation

c) excretion

d) reproduction

26
...
Amphioxus is usually found
a) floating in water

b) buried in sand

c) in shallow pits

d) in deep water

28
...
In Amphioxus the velum is fringed with
a) 8 velar tentacles

b) 12 velar tentacles

c) 20 velar tentacles

d) 10 velar tentacles

71

30
...
The number of myotomes in amphioxus may vary from
a) 80 or more

b) 60 or more

c) 100 or more

d) 50 or more

32
...
In Amphioxus the wall of the pharynx is perforated by
a) 180 or more gill slits

b) 150 or more gill slits

c) 200 or more gill slits

d) 80 or more gill slits

34
...
In Amphioxus the mucous glands secrete a sticky mucous for
a) entangling the food materials

b) capturing the food materials

c) digesting the food materials

d) engulfing the food materials

36
...
The blood in amphioxus is
a) coloured

b) watery

c) colourless

d) all the above

38
...
The nephridium of amphioxus bears about
a) 500 solenocytes

b) 200 solenocytes

c) 600 solenocytes

d) 800 solenocytes

72

40
...
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

42
...
Limbless amphibians are
(a) Frogs
(c) Salamanders

(b) Toads
(d) Caecilians
Part II

Give very short answers
...
Define biosphere?
2
...
What is the characteristic feature of biological taxonomy?
4
...
What is a taxon?
6
...
Why do we call nematocysts as stinging cells?
8
...
What are amniotes?
10
...
give an example
11
...
Name the two types of setae in an earthworm
13
...
What are chlorogogen cells
15
...

16
...
Write short notes on a) oral hood b) oral cirri
18
...


73

19
...
What is endostyle? what is its function?
21
...

22
...
What are flight muscles ?
24
...
Name the subclasses under mammalia
...
Mention any one characteristic feature of the primates
...
What are cryptozoites?
28
...
What is tertian malaria?
30
...
What is ‘pecten’?
Part III
Answer breifly
1
...

2
...
Give an account of the basic principles of nomenclature
...
Differentiate bracketed and indented keys for identifieation with a suitable
example
...
Give an account of urinary or excretory system of Pigeon
...
Explain the structure of the nephridium
7
...

8
...

9
...

10
...

11
...
Explain the male reproductive organs of earth worm
...
Draw a neat labelled sketch to show the external morphology of amphioxus
...
Explain the excretory system of amphioxus
...
Draw and label the parts in a cross-section of amphioxus through
pharyngeal region
...
Describe the structure of the brain of the pigeon
...
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
...
Explain the digestive system of earthworm
...
Give a detailed account on the general characters of 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
...
Explain the digestive system of amphioxus with diagram
...
Describe the blood vascular system of amphioxus with the aid of a neat
diagram
...
Describe the arterial system of Pigeon
11
...


75

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
...


78

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

79

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

82

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
...


83

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
...


84

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
...


85

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
...


88

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-

95

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

96

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
...


97

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
...
Congo Red dye can be used to stain
a) Plant cell

b) Nerve cell

c) Gland cell

d) Yeast cell

3
...
H
...
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

5
...
In a microscope the light is focussed on the object through
(a) condenser lens

(b) objective lens

(c) occular lens

(d) oil immersion lens

7
...
In microscopy a nucleus is normally stained using
(a) Neutral red

(b) Janus green B

(c) Eosin

(d) Hematoxylin

9
...
The lipids of plasma membrane are mainly
a) Glucose molecules

b) Phospholipid molecules

c) Protein molecules

d) All the above

11
...
In the plasma membrane the lipid bilayer is covered by
(a) proteins

(b) carbohydrates

(c) water molecules

(d) nucleic acid

13
...
Animal cells usually have
a) single golgi apparatus

b) double golgi apparatus

c) Poly golgi apparatus

d) dictyosome

15
...
Which of the following is called as the cell respirataory organelle
(a) ribosomes

(b) lysosomes

(c) golgi bodies

(d) mitochondria

17
...
Lung cancer may be caused by
a) cigarette smoking

b) shale oil

c) radio active ores

d) beta-naphthylamine

19
...
Which of the following cell may not contain golgi apparatus
(a) epithelial cells

(b) glandular cells

(c) RBC

(d) secretory cells

21
...
Lysosomes are involved in :a) intracellular digestion

b) extracellular digestion

c) Phagocytosis

d) pinocytosis

23
...
The movement of the flagellum is regulated by
(a) plasma membrane

(b) nucleus

(c) basal body

(d) ribosomes

25
...
The nucleus is found in all the
a) Bacteriae

b) Viruses

c) Eukaryotic cells

d) All the above

27
...
Write a note on phase contrast microscope
...
Name the new branches of science related to cytology
...
What is ‘limit of resolution’ in the functioning of a microscope ?
4
...

5
...
Name any four vital dyes or stains
...
What is Mounting?
8
...

9
...
Write any two functions of endoplasmic reticulum
...
Mention any four enzymes which are seen in Lysosomes
...
Write any two functions of centrioles
...
What is ‘autolysis’ ?
14
...

15
...

16
...

17
...
What is a ‘fluid mosaic model’ of a plasma membrane ?
19
...

20
...

Part - III
1
...

2
...


102

3
...

4
...

5
...

6
...

7
...

8
...

Part - IV
1
...

2
...

3
...

4
...

5
...

6
...

7
...

8
...


103

3
...
1
...
It takes its root from ‘ana’ and
‘tome’ (ana-up ; tome-cutting)
...
The Human Anatomy
provided the necessary knowledge for surgery and medicine
...
They removed internal organs of cadavers being mummified
...
In India
during 500 - 491 BC Susruta performed cataract operation
...

The year 1543 AD was significant due to publication of an accurate
book on Anatomy by Andreas Vesalius
...
These earlier works
were followed by the discovery and accurate account of each and every organ system and organs in human body
...


Gray’s Anatomy
Eventhough several books had been written on Human
Anatomy, a monumental work titled ‘Anatomy : Descriptive and
Surgical by Henry Gray is unique in its discriptions
...
It is in print
continually for the past 145 years
...

Henry Gray was born in Windsor, London in 1827
...
He was a brilliant medical student at St
...


104

3
...
1 The Integumentary System
The word integument means covering
...
It protects internal structures, prevents the entry
of infectious agents, reduces water loss, regulates body temperature, produces
vitamin D and detects stimuli such as touch, pain and temperature
...

The skin or integument rests on layers of cells called hypodermis
...
It supplies
blood vessels and nerves to the skin
...
3
...
1
...
The dermis is mostly formed of connective tissue having fibroblasts, adipose cells and macrophages
...
The dermis accommodates nerve endings, hair follicles, smooth muscles
and glands
...
The papillary layer has projections called papillae
...
It is dense in nature
...


Epidermis :- The epidermis is made up of stratified squamous epithelium
...
It contains mel105

anocytes giving colour to the skin
...
Hence they are called as keratinocytes
...
3
...
2
...

As new cells are formed, the older cells are pushed to the surface
...
Gradually the shape and chemical
nature of the surface cells will get altered
...

This process is called keratinization
...
They are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum
...
It consists of
one layer of columnar cells
...
Above
this layer stratum spinosum is seen
...

The stratum granulosum is the next upper layer
...
Above this layer stratum lucidum occurs
...
The top most layer is called the stratum corneum
...
These cells get filled
with keratin
...
The cornified cells are surrounded
by a hard protective envelope
...
All five epithelial layers are seen
in the thick skin
...

Thick skin is formed in the soles of the feet, the palms of hands and tips of
fingers
...
In the thin skin each epithelial layer inturn has few layers of cells
...

106

Callus :- The regions of skin subjected to constant friction or pressure are
thickened to form the callus
...


Skin colour :- The colour of the skin is due to pigments in the skin
...
Normally the colour is caused by the pigment melanin
...
It protects the body from sun’s ultraviolet rays
...
Melanin production is genetically determined
...

Skin dervatives
Hair :- The hairs are integumentary structures
...

While the shaft projects above the skin, the root remains well below the surface
...
It is an expanded region
...

These are arranged in three concentric layers called the medulla, the cortex
and the cuticle
...
Major
part of the hair is formed of a single layer of cells
...
3
...
3
...
The colour of the hair is genetically determined
...
Grey hair has a mixture of
faded, unfaded and white hairs
...

The growth stops at specific stages
...
The hairs on the head grow for a period of three years and rest for
1-2 years
...
Contraction of these muscles cause ‘goose flesh’ making the
hairs to ‘stand on end’
...
The sebaceous glands are located in the dermis
...
These glands are connected by a duct to the upper part of the hair
follicles
...


glandular lobe
lactiferous duct

nipple

fat

Fig
...
1
...
The mammary gland

The most common type of sweat gland on the skin are the merocrine
glands
...
They open directly on to the
skin through sweat pores
...
They are the deep coiled
portion and the duct which passes to the surface of the skin
...

Nails :- Each nail is made up of two parts
...
The nail body is the visible part
...

The proximal and lateral edges of the nail are covered by nail fold
...
3
...
5
...
The free edge of the nail body is the hyponchium
...
A small white region seen at the
base of the nail is the lunula
...
The nails grow at an
average rate of 0
...
2 mm per day
...
2
...

This system provides ‘the shape’ to the body
...
It also helps to hold weight
...
This system is also useful in locomotion
...
The bone marrow is
the site for the production of erythrocytes
...
3
...
1
...
Hands and legs
have long bones
...
Carpals (wrist bones)
and tarsals (antkle bones) are shorter
...
Skull
bones, ribs, sternum and scapula (shoulder blade) are flat bones
...


Structure of a typical long bone
A bone is covered by a double layered sheath called the periosteum
...
It is a dense collagenous layer having blood vessels and nerves
...
The long bony part is the diaphysis or shaft
...

head
neck

articular cartilage
epiphysis
epiphyseal plate
cancellous bone
compact bone
periosteum

body

diaphysis
medullary cavity
endosteum

patellar groove
Fig
...
2
...
Long bone - Femur or thigh bone

The end of the bone consists of epiphysis
...
The outer surface of epiphysis is formed of compact bone
...
It is made
up of hyaline cartilage
...

The cavity inside the diaphysis is called the medullary cavity
...
The cavity inside the
diaphysis in adults contain yellow marrow
...
The
medullary cavity of the epiphysis contains red marrow concerned with blood
cell formation
...
The bones
are named according to their position in the body
...
The axial skeleton consists of the skull, hyoid bone, vertebral column and thoracic cage
...
In human body, there are 206 bones, of these 80 are in the axial
skeleton, 126 in the appendicular skeleton
...
(details as
found below)

Axial skeleton - It forms the upright axis of the body
...

a) Skull - The human cranial capacity is about 1500 cm 3
...
It protects the brain
...
The lower jaw or mandible remains specially attached to the skull
...
They are one pair each of
parietal and temporal, individual bones as frontal, sphenoid, occipital and
ethmoid
...
The sutures are immovable joints
...
3
...
3
...
3
...
4
...
Of these maxilla, zygomatic,
palatine, lacrymal, nasal and inferior nasal koncha remain as pairs
...

The parietal and occipital bones are major bones on the posterior
side of the skull
...
The side of the head is formed of the parietal and the temporal bones
...
This
opening is meant for transmitting sound waves towards the eardrum
...

Anterior to the sphenoid bone is the zygomatic bone or cheek bone
...
The upper jaw is formed of the maxilla
...

The major bones seen from the frontal view are the frontal bone,
zygomatic bone the maxillae and the mandible
...
The two orbits are meant
for accommodating the eyes
...
The bones
forming the oribits are the frontal, sphenoid, zygomatic, maxilla, lacrymal,
ethmoid and palatine
...
They
are Maleus (2), incus (2) and stapes (2)
...
The renal artery and nerves enter and the renal vein and the ureter
exit at this region
...

Each kidney is enclosed by a fibrous connective tissue layer, called
the renal capsule
...
The medulla consists of several cone-shaped
renal pyramids
...
Extension of the cortex called renal columns, project between the pyramids
...
They are pointed toward the renal sinus
...
The
minor calyces of several pyramids join together to form larger funnels called
major calyces
...
The major calyces converge to form an enlarged channel called the
renal pelvis
...
The ureter
leaves the kidney and gets connected to the urinary bladder
...

The basic functional unit of each kidney is the nephron
...
3 million nephrons in each kidney
...
Each nephron consists of an enlarged terminal end called the renal corpuscle, a proximal tubule, a loop
of Henle and a distal tubule
...

The renal corpuscle, proximal tubule and distal tubules are in the renal cortex
...

efferent blood vessels
afferent blood
vessels

uriniferous
tubule

Bowman’s capsule
glomerulus
proximal tubule
distal tubule
loop of Henle

Malpighian capsule

Fig
...
11
...
Nephron

162

collecting tubule

Most nephrons measure 50-55 mm in length
...
These are called the
juxtamedullary nephrons
...

The renal corpuscle of the nephron consists of a Bowman’s capsule
and a bunch of capillaries called the glomerulus
...
The outer parietal layer is composed of
simple squamous epithelium
...
It consists of specialized cells called podocytes
...
There is a basement
membrane between the endothelial cells of the glomerular capillaries and the
podocytes of Bowman’s capsule
...

The glomerulus is supplied with blood by an afferent arteriole
...

The cavity of Bowman’s capsule opens into the proximal tubule
...
It is approximately 14mm long and 60 µm in diameter
...
Each
loop has a descending limb and an ascending limb
...
The loops of Henle
that extend into the medulla become very thin near the end of the loop
...
The distal tubules, also called the
distal convoluted tubules are not as long as the proximal tubules
...
They arise medially at the renal hilum to reach the urinary bladder
...
The urinary bladder is a hollow muscular bag
...
The size of the bladder depends on the presence or
absence of urine
...
Filling upto
500 ml is tolerated
...
The ureters enter the
bladder inferiorly on its posterolateral surface
...
At the junction of the urethra with the urinary bladder

163

smooth muscles of the bladder form the internal urinary sphincter
...
The sphincters control
the flow of urine through the urethra
...
In male the urethra is 18-20cm long
...
It is about 4 cm long and 6 mm in diameter
...
12
...
This
process, apart from ensuring a healthy progeny provides an oppurtunity to
produce enormous range of genetically varied offsprings
...
Such
adaptations have resulted in suitable morphological, anatomical and behavioral modifications
...
The functioning is
in accordance with psychological and endocrinological thresholds
...


Male reproductive organs
The male reproductive system consists of the testes (singular : testis), epididymides (sing: epididymis), ductus deferentia or vasa deferentia
(sing : ductus deferens, vas deferens), urethra, seminal vesicles, prostate
gland, bulbourethral glands, scrotum and penis
...
3
...
1
...
These are suspended in the scrotum by scrotal tissues
...
They do not develop normally at usual body temperatures
...

The left testis usually is 1 cm lower than the right
...
Its weight varies from 10
...

The outer part of each testis is a thick, white capsule called tunica
albuginea
...
The septa
divide each testis into about 300-400 cone shaped lobules
...
Sperm cells develop within the seminiferous tubules
...
3
...
2
...
S
...
The combined length of the
tubules in both testes is nearly 800 metres
...
The rete testis in turn open into efferent ductules
...
These cells help
to move the sperm cells out of the testis
...
It occurs on the posterior side of the testis
...

165

Vas deferens or ductus deferens : It emerges from the tail end of the
epididymis and ascends along the posterior side of the testis
...
Collectively
these structures constitute the spermatic cord
...
This cord enters into
the pelvic region
...
At
this region the vas deferens is surrounded by smooth muscles capable of peristaltic contraction
...

Ejaculatory duct : Nearer to the ampulla of each vas deferens there is a sac
like seminal vesicle
...
These ducts are about 2
...
They project into the prostate gland
and end by opening into the urethra
...
It is about 20 cm long
...
The urethra is divided into three parts
...
The prostatic Urethra - It is closest to the bladder and passes through the
prostate gland
...
The membranous urethra - It is the shortest part of the urethra and it
extends from the prostatic urethra
...
The spongy urethra or penile urethra - It is the longest part of the
urethra
...
There are several minute mucus secreting urethral glands opening into
the urethral passage
...
It consists of two parts namely the
radix or root and the corpus or body
...
The corpus is normally pendulous
...

corpus cavernosum
spongy urethra

corpus spongiosum
Fig
...
12
...
C
...

Flooding these tissues with blood causes the penis to enlarge and become
firm
...
Most of the corpus is formed of the corpora
cavernoas
...
Its
swollen base is the corona glandis
...
It is loosely connected to the tunica
albuginea
...
It overlaps the glans penis
...


Seminal vesicles - These are two sac-like structures located between the
bladder and rectum
...
Their secretions contribute about 70% of the seminal fluid
...
It is partly glandular and partly fibromuscular
...
It is about 3 cm in
diameter
...

The muscular part of the prostate may help in dilating the urethra to
hold the seminal fluid (3-5ml) during the period of sexual excitement prior to
ejaculation
...
It may project into
the bladder and interrupt urination
...
They are small round masses
about 1 cm in diameter
...
Its secretion may control genito-urinary diseases
...
It contains the testes and their associated
ducts
...
Its left side is usually
lower
...
The scrotal skin is thin and pigmented
...


Female reproductive organs
In human female the internal reproductive organs are the ovaries,
uterus, uterine tubes and vagina
...

167

Ovaries - These are paired structures
...
They are greyish pink in colour
...
They are about 3cm long,1
...


ureter
fallopian tube or
uterine tube ovary
uterus
urinary bladder

cervix
rectum

pubic bone
urethra

anus

Fig
...
12
...
Human female reproductive organs

The ovary is attached to the posterior surface of the inner body wall
by a membranous fold called the mesovarium
...


Ovarian structure - In young female the surface of the ovary is covered by
a layer of ovarian surface epithelium
...
Beneath the epithelium the ovary is surrounded by a tough coat
named tunica albuginea
...

secondary follicle
primary follicles

cortex

granulosa cells

mesovarium

medulla
theca interna
cumulus mass
corpus luteum

tunica albuginea

Fig
...
12
...
Histology of the Ovary

The overy proper is divisible into two regions, namely the cortex and
the medulla
...
The medulla is
interior
...

168

After puberty the cortex forms the major part of the ovary
...
Their size depends on the stage of menstrual cycle or age
...
The follicles are embedded in the stroma
...
At birth, the primordial follicles are found in the superficial zone of
the cortex
...
Each one of them is surrounded by a single layer of flat follicular
cells
...
The various follicular stages are :

1
...
The follicular membrane or membrana granulosa becomes multilayered
...
It has an outer thick layer called the zona
pellucida
...


2
...
The granulosa cells surround
the oocyte and form a mound of cells called the cumulus ovaricus
...
The theca interna is well established
...
Tertiary follicle - Only one follicle reaches the tertiary stage
...
Now it is called the graffian follicle
...
Finally the wall of the follicle ruptures and the
contents are released into the peritoneum
...

At birth the ovary of the child contains about 1 million oocytes
...
Of the
40,000 oocytes only about 400 undergo ovulation during the reproductive years
...
The walls of the empty follicle
collapses and fold extensively
...

They are now termed as luteal cells
...
In
pregnancy the corpus luteum persists
...
The connective tissue cells get enlarged
...
In course of time it shrinks and
disappears
...
Each one is associated with a ovary
...
The terminal part of the tube is enlarged to form
the infundibulum
...
The opening is called the
ostium
...
The part nearer to the infundibulum is called the ampulla
...
That part of the tube
nearer to the uterus is called the isthmus
...
The tubular part entering into the uterus is called the uterine or intramural part
...
3
...
6
...
It is pear shaped
...
5cm long and 5 cm wide
...

During pregnancy its weight may go upto 1kg
...
The narrower part is called as the cervix
...
The middle part is the body
...

The wall of the uterus is three layered
...
The major part of the wall is made up of the
next layer called the myometrium or muscular coat
...
The endometrium
is a functional layer
...


Vagina - It is the female copulatory organ
...
It is
about 10 cm long
...
The vaginal passage is used during intercourse and it allows menstrual flow and child birth
...
It consists of the vestibule and its surrounding structures
...
It contains the vaginal opening and the urethral opening
...

Mons pubis - It is a rounded eminence situated anteriorly
...
It is covered by coarse hair at the
time of puberty
...


Labia majora - These are two longitudinal folds of skin
...

Labia minora - These two small skinfolds lie between the labia majora
...

Clitoris - It is homologus with male penis
...
It is
found in the anterior margin of the vestibule
...


Hymen vaginae - It is a thin mucous membrane
...
If the membrane completely closes the vaginal opening,
it should be removed to allow menstrual flow
...
In some women it may be
absent
...

External urethral opening - This opening is about 2
...

It is anterior to the vaginal opening
...


171

Self evaluation
Choose the correct answer
1
...
The goose flesh is formed due to the contraction of
a) diaphragm

b) errector pili

c) trapezius muscle

d) gluteus maximus

3
...

a) melanin
c) neutral red

b)haemoglobin
d) Janus green

4
...
The cervical vertebra supporting the head is
a) axis

b) atlas

c) sacral

d) lumbar

6
...

a) skull bone
c) sternum

b)ribs
d) all the above

7
...
The bone that holds the upper limb away from the body is
a) scapula
c) clavicle

b)pelvic bone
d) femur

172

9
...
In shape the deltoid muscle is a
a) square

b) slender

c) circular

d) triangular

11
...
The largest salivary glands are
a) parotid

b)submandibular glands

c) sublingual glands

d) labial glands

13
...
The length of the duodenum in human alimentary canal is
a) 8 cm

b) 1
...
The lung is surrounded by
a) duramater

b) pericardial membrane

c) pleura

d) meninges

16
...
The reduction in blood pressure may be caused due to
a) distributing vessels

b) resistance vessel

c) exchange vessels

d) reservoir vessels

173

18
...
The wall of the blood vessels are supplied with blood by
a) vasa nervosum

b) exchange vessels

c) vasa vasorum

d) capacitance vessels

20
...
Spleen is located on the left side of
a) the abdominal cavity

b) the thoracic cavity

c) the lung

d) the kidney

22
...
The cerebral hemispheres are connected by a sheet of nerve fibres called
a) corpora quadrigemina

b) choroid plexus

c) corpus callossum

d) cauda equina

24
...
The Melbomian glands produce
a) sebum

b) tear

c) wax

d) oil

26
...
The hypophysis is connected with the brain through
a) pars tuberalis

b) adeno hypophysis

c) hypothalamus

d) pars distalis

28
...
The average weight of kidney in adult female is
a) 150 g

b) 135 g

c) 75 g

d) 250 g

30
...
The interstitial cells are otherwise called
a) Leydig cells

b) Sperm cells

c) Glandular cells

d) Secretory cells

32
...
The inner layer of membrane lining the uterus is
a) perimetrium

b) myometrium

c) endo metrium

d) serous layer

34
...
What is keratinization ?
2
...
What are floating ribs ?
4
...
Name the two catagories of bones
...
What is foramen magnum ?
7
...
Differentiate skeletal and visceral muscles
...
Name the kissing muscles
10
...

11
...

12
...
What is gingiva
...
Name the three pairs of Salivary glands
...
Name the four parts of the Colon
...
What is Adam’s apple ?
17
...
What is acinus ?
19
...
Name the layers found in the wall of the heart
...
Provide the root of systemic circulation
22
...
What are sulci and gyri ?
24
...
What is choroid plexuses ?

176

26
...
What is Rathke’s pouch ?
28
...
What is the function of the ciliary muscles ?
30
...
Name the parts of the anterior pituitary
...
Name the layers of the adrenal cortex
...
What is the role of prostate glands ?
34
...
What is graffian follicle ?
Part - III
1
...

2
...
Describe the structure of typical human vertebra
4
...

5
...

6
...
Draw a neat labelled sketch of a tooth
...
Give a description of the human liver
9
...

10
...

11
...
Write notes on portal circulation
13
...

14
...
Give an account of the thymus
16
...
Describe the structure of a Neuron with diagram
...
Explain the cross section of spinal cord with diagram
19
...
Explain the organization of the lacrimal apparatus in human eye
21
...
S
...

22
...

23
...

24
...
Provide the structure of human kidney
26
...

27
...

28
...
Explain the structure of the various skin-dervatives with suitable diagrams
...
Name bones in the skull of man
...

3
...

4
...

5
...

6
...

7
...

8
...

9
...
Describe the systemic and pulmonary blood circulations in man with
diagram
...
Explain the structure of human heart
...
Provide a detailed description of the anatomy of human brain
13
...


178

14
...

15
...
Write an essay on the primary sex organs and associated structures of a
human male
...
Explain the structure of female reproductive organs in human with suitable
diagrams
...
Name the muscles in the human trunk region and explain how they work
...
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)
182

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
183

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
185

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
186

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

188

The male is very small and microscopic
...
The males normally live as parasites attached to females
...
However a larva settling on the
proboscis of an adult female becomes a male individual
...
, in the absence of a female) it develops into female
...

From these observations it could be inferred that the proboscis of adult female
secretes some hormone like substance and that substance suppresses femaleness and induces maleness in the larvae which remains attached
...
4 Sex - linked Inheritance
Most of the inheritable characters are controlled by genes located in
autosomes
...
Mendelian ratios are not obtained for those characters for
which genes are exclusively located either in X or Y chromosome
...
Similarly,
that the genes occur exclusively on Y chromosomes are called the holandric
genes
...
Thus the sex linked inheritance may be X- linked, Y- linked or XY
linked
...
H
...
He found that the gene for
white eye colour is X - linked
...


Red eyed female x white eyed male
When a wild red eyed female Drosophila is crossed with a mutant
white eyed male, all the F1 individuals (males and females) have red eyes
...
Among the
males 50 % had red eyes and another 50 % had white eyes
...
When these red eyed female individuals and white
191

eyed male individuals of F1 are intercrossed the F 2 generation possessed 50 %
red eyed and 50 % white eyed females
...

Red eyed female

White eyed male

Parents
Red eyed female

Red eyed male

F1

Red eyed female

Red eyed female

Red eyed male White eyed male

F2

Fig
...
4
...
Drosophila - Red eyed female x White eyed male

Sex linked inheritance in Humans
Most of the sex linked characters in humans are X - linked
...
Most of them are recessives
...
The cone cells are sensitive to red, green and violet
light
...

The recessive form of this gene is incapable of producing colour sensitive cones
...

The frequency of colour blind women is less than colour blind men
...
However the female will be a carrier for the
recessive gene
...


4
...
This finding is not always true
...

This phenomenon of multiple effects of a single gene is called pleiotropism
...
If the gene causes other less conspicuous
phenotypic changes, it is known as secondary effect
...

Vestigeal wings in Drosophila are caused by a recessive gene
in homozygous condition
...
They are (i) the small halters or balancers behind the wing
(ii) structure of reproductive organs (iii) egg production (iv) life duration and
(v) bristles on the body
...
They were able to identify a dominant
trait namely brachydactyly that agreed with the Mendelian theories and showed
Mendelian ratio in the human populations
...

An objection to this example was raised
...
But in reality brachydactyly is seen rarely in
human population
...
However, until 1908 it remained unexplained among the
scientists
...
E
...
This theory explains
why some characters though dominant (like brachydactyly) appear rarely in a
population
...
4
...
1
...
It simply means, that the
common traits remain common and the rare traits remain rare
...
The relative abundance of a genotypye in a
population is referred to as its genotypic frequency
...
4
...
2
...
‘A’ remains dominant to ‘a’
...
Then the number of individuals (or frequency) with AA is ‘p’ and the
number of individuals with ‘aa’ (or frequency of aa) is ‘q’
...
As both the characters are considered as
homozygotes the individuals with AA will produce all gametes with ‘A’
...

If all the gametes are viable, combine at random, all have the chance
of survival and no new gametes are introduced in to the population, we can
calculate the proportion of next generation with genotype AA using the usual
Punnet Square method
...

Problems: This could be proved mathematically p + q = 1 on both sides
...
Here each side of the
square represents one unit
...
The points are chosen randomly
...
The area of each rectangle
represents the frequency of the resulting progeny (or) the proportion of the
next generation having the genotype specified in each cell
...
00 (or) 100% of the
population
...

195

Substitute these values for the symbols p and q and find out the percentage of
heterozygotes found in the population when it reaches the equilibrium
...


p = 40% , q= 60%
p + q = 1 or 100
i
...

It is clear that this law is applicable only to populations with following
features
a) Infinitely large populations
b) No mutation
c) No selection
d) Random mating
e) Isolated from any other population of the same species
...
Such populations
that has reached equilibrium remain unchanged from generation after
generation
...

1
...
Assume that brown eyes are dominant to blue eyes
...
What proportion of the population is
heterozygous
...
The skin colour agouti in rabbits has the genotype
(a) CC

(b) Cca

(c) Cc h

(d) all the above
...
The alternative forms of a gene are
(a) allelomorphs
(c) heterozygous

(b) multiple alleles
(d) homozygous
...
The universal recipient is
(a) ‘O’ Group
(c) ‘A’ Group

(b) ‘AB’ Group
(d) ‘B’ Group
...
ABO blood group in man is an example for
a) Pleiotropism

b) multiple allelism

c) x - linked inheritance

d) y - linked inheritance

5
...

(a) Yule
(c) Galton

(b) Mendel
(d) C
...
Davenport
...
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

8
...
The poly ‘X’ females are
(a) super females
(c) bisexuals

(b) hermaphrodites
(d) intersex

10
...
Most of the sex linked characters in humans are
(a) Y-linked
(c) X linked

(b) XY linked
(d) all the above
...
X/A ratio in super females is
a) 1
...
0

c) 0
...
5

13
...
The genotypes better adapted for malaria is
(a) HbA HbA

(b) HbA HbS

(c) HbS HbS

(d) all the above

15
...

1
...
Provide the genotypes for himalayan albino rabbits
3
...

4
...
What was the opinion of the biometricians as geneticists?
6
...
What is Hermaphroditism?
8
...
What are holandric genes
...
What are modifying genes
...
What are secondary sexual characters?
12
...
Write down the symptoms of Turner’s syndrome
...
Explain multiple factor hypothesis
...
Differentiate a normal RBC from a diseased RBC
...
What will be the nature of the F 2 progeny, if a coloured rabbit is crossed with
an albino?
2
...

3
...


199

4
...
Write notes on quantitative inheritance
...
Provide an account on turner’s syndrome and klinefelter’s syndrome
...
Describe the process of sex determination in Bonellia
Part - IV
Answer in detail
1
...

2
...

3
...

4
...


200

5
...
A zygote is a single celled
structure
...
These phases
include cleavage, gastrulation, neurulation, organogenesis and the period of growth and histological differentiation
...
Till later stages of development a fundamental uniform pattern in
development can be observed
...

Realising the mode of formation of a young individual of the next generation has always interested human mind
...
The
‘Susruta samhita’, a monumental Indian medical book, written during
second or third century A
...
, describes the development of a human child in
the mother’s womb
...

His classical work De Generatione Animalium is concerned with the generation of animals
...
In his another work “De Historia Animalaium”, Aristotle
provides an account of the development of the hen’s egg
...
By observing the development of hen’s egg he concluded that the
development always proceeds from simple formless beginning to the
complex organization of the adult
...
Through his remarkable observation and speculations
Aritotle established ‘embryology’ as an independent field in science
...

After the period of early Greek thinkers this discipline once again got
the attention of the scientists from the beginning of the 17 th century
...
Haeckel, O
...
B Wilson, Spemann, C
...
Modern embryology has utilised all tools
made available from other branches of science and diversified into branches
such as ‘Experimental embryology’, ‘Chemical embryology’, ‘Comparative embryology’ and Descriptive embryology
...


Gametogenesis :
The process of embryonic development in sexually reproducing
multicellular organisms is made possible through processes of
gametogenesis and fertilization
...
It happens in primary sex organs
called gonads
...
These cells are responsible for the production of gametes
...
5
...
1
...
The primordial
germ cells of these tubules produce cells which ultimately become sperm
202

mother cells or spermatogonia
...
These are diploid cells
...
Initially the I Meiosis results in the formation of
secondary spermatocytes
...
The
spermatids are haploid in nature
...


Oogenesis :
A similar process happens inside the female gonad, namely the ovary
for the production of Ova
...
These stages are conducted by meiotic cell divisions
...


Fertilization :
Embryogenesis could occur only after the fertilization of the ovum or
egg
...
Thus all the somatic
cells of the embryo will remain diploid
...
During the process of
fertilization the sperm and ovum of the same species approach and come in
contact with each other
...
The haploid nuclei of the sperm and ovum fuse, resulting in the formation
of a diploid zygote nucleus
...


5
...
Types of eggs
For the embryo to develop inside a fertilised egg nutrition is needed
...
It normally
depends on the duration of development
...

It may be ‘fatty yolk’ or protein yolk’
...
Due to accumulation of yolk a maturing egg rapidly
increases in size
...
Chemically, the yolk platelets contain two main proteinaceous substances namely phosvitin and lipovitellin
...
The amount of yolk influences cleavage and
gastrulation methods
...


Amount of yolk and egg types :
In certain animals the developmental stages are not very elaborate
...

Such conditions remain in animals like Hydra, Sea urchin, Amphioxus and
Placental mammals
...
Such eggs are said to be
Microlecithal or oligolecithal
...
Hence for such eggs the amount of yolk is considerable in quantity
...
Such eggs are produced by annelid worms, molluscs and amphibians
...
The growth period is sufficiently long
...
Such eggs
are termed as Megalecithal or Macrolecithal eggs
...
Further these eggs are covered by
a calcareous shell
...

Such eggs are called cleidoic eggs or land eggs
...
5
...
2
...

The pattern of cleavage and the consequent gastrulation processes
are affected by the distribution of yolk within the egg
...

204

1
...

Eggs of this type have the yolk disbursed in the entire cytoplasm
...
5
...
3
...
In such eggs the cleavage will be deeper and may bisect the eggs
connecting the two poles
...

2
...


animal pole
nucleus

yolk
vegetal pole
Fig
...
1
...
Telolecithal egg

All eggs have polarity
...
The polar
nature is mainly due to the denser material in the cytoplasm, namely yolk
...
The
cytoplasm with the nucleus will occupy the upper animal pole
...
Thus the eggs having a
polarised distribution of yolk in the cytoplasm are referred to as Telolecithal
eggs
...

3
...


cytoplasm
shell

•
Fig
...
1
...
Centrolecithal egg

205

yolk
nucleus

An egg need not be spherical always
...
The pattern of cleavage and further gastrulation also
deviate from that of the vertebrates
...
However, the eggs of echinoderms
are similar to that of the vertebrates
...
2 Cleavage and types - Frog’s egg
...
It is
initiated by the sperm during fertilization
...

The process of cleavage or cellulation happens through repeated mitotic divisions
...
In later
stages of development the blastomeres occupy different regions and differentiate into several types of body cells
...
The entire process of cleavage in frog’s egg was studied by Prevost
and Dumas in 1824
...

From all these studies it has become clear that all divisions in cleavage
are mitotic
...
In the eggs of sea urchin division of the blastomeres can be observed every 30 minutes
...
During cleavage there is no growth in the blastomeres
...
The cleavages result in a compact mass of blastomeres called morula
...

While the wall of the blastula is called the blastoderm, the central cavity is
called the blastocoel
...
Depending on the position of the cleavage furrow the planes of cleavage are
named
...
Meridional cleavage: The plane of cleavage lies on the animal vegetal
axis
...
Thus the egg is divided into two equal
halves
...
Vertical cleavage: The cleavage furrows may lie on either side of the
meridional plane
...
The cleaved
cells may be unequal in size
...
Equatorial cleavage: This cleavage plane bisects the egg at right angles
to the main axis
...
It divides the egg into two
halves
...
Latitudinal cleavage: It is similar to the equatorial plane, but it lies on
either side of the equator
...

Influence of yolk on cleavage
Yolk is needed for embryonic development
...
Somehow with all the influences of yolk the
developmental procedures are so adapted and modified that a well formed
embryo will result
...

The amount of the yolk and its distribution affect the process of cleavage
...

1
...
Such a cleavage may be either equal or unequal
...
Eg: Amphioxus and
placental mammals
...
Among the
blastomeres there are many small sized micromeres and a few large sized
macromeres
...
Meroblastic cleavage - In this type the cleavage furrows are restricted to
the active cytoplasm found either in the animal pole (macrolecithal egg) or
superficially surrounding the egg (centrolecithal egg)
...

(a) Discoidal cleavage - Since the macrolecithal eggs contain plenty of yolk,
the cytoplasm is restricted to the narrow region in the animal pole
...
Such
a cleavage is called discoidal meroblastic cleavage
...

207

(b) Superficial cleavage - In centrolecithal eggs, the cleavage is restricted to
the peripheral cytoplasm of the egg
...

Laws of cleavage
Apparently there are several cleavage patterns
...
The cleavages are governed by certain
basic principles or laws
...
Sach’s laws - These laws were proposed by Sach in 1877
...

2
...

Cleavage of fertilized egg in Frog
...
The cleavage
occurs as follows
...
S

blastula-entire

Fig
...
2
...
Cleavage in frog’s egg

1
...
Initially, a furrow appears at the
animal pole
...
It cuts
the egg through its median animal-vegetal polar axis and results in two equalsized blastomeres
...
The second cleavage furrow is again meridional
...
It is a holoblastic cleavage affecting both the
blastomeres of the first cleavage
...

208

3
...
Such a furrow is due to the influence of yolk
concentration in the vegetal pole
...
It results in the formation of eight blastomeres
...
They are named as macromeres
...
They are named as
micromeres
...

4
...
They are
unequal
...
These cleavages result in the production of 16 blastomeres
...
As a result of further cleavages, a ball of several small blastomeres result
...
The larger blastomeres are called the macromeres
...
5
...
2
...
S of Frog blastula

At the final stages of cleavage the embryo acquires a characteristic,
mild, oblong shape
...
The morula initially
contains a shallow cavity called the blastocoele
...
However the blastocoele mostly remains in the animal pole region in the middle of
the micromeres
...
The blastoderm remains
two cell thick in the animal pole
...

It has been reported that around 12th cleavage the blastula possesses
about 4096 cells
...

The ultimate blastula is a ball of blastomeres which have to form different embryonic body layers and organs of the body
...
A map showing various
209

organ forming, areas on the blastula is called the ‘fate map’
...
It also shows the
‘zone of involution’ and ‘zone of invagination’ for the next stage of gastrulation
...
3
...
During this process the blastodermal cells begin to move
...
During this movement at
one region on the blastula, the cells wander inside and occupy the blastocoelic
cavity
...
They move toward the interior of the blastula
...
A deepening of the
invagination results in a cavity called the archenteron or gastrocoel
...

The blastopore gradually assumes a crescentic shape
...
The region dorsal to the blastoporal opening is called the ‘dorsal lip’
...

dorsal lip

Fig
...
3
...
Formation of dorsal lip

The surface cells representing several prospective zones of the embryo begin to wander inside through the blastopore
...

blastoderm

blastocoele

dorsal lip of blastopore

invagination of macromeres

Fig
...
3
...
Invagination of Endodermal cells

210

Initially, the first pharyngeal endodermal cells undergo invagination over
the dorsal blastoporal lip
...
They are followed
by other cells
...
Thus the blastocoelic cavity gets reduced
...
It is called the gastrocoel
...
The interior region of the archenteron gradually transforms into the pharyngeal region
...
The
mesodermal and endodermal cells gradually occupy their positions
...
The involution results in the positioning of chordamesodermal cells and pharyngeal endodermal cells
...
5
...
3
...
While the exterior chorda-mesodermal cell involute inside, their place is taken up by the ectoderm
...
Epiboly causes overlapping or ‘the roofing over’
of the gastrula by the ectoderm
...
The
closing cells of the blastopore constitute the yolk-plug
...


211

The process of gastrulation converts the blastula into a spherical, bilaterally symmetrical, triploblastic gastrula
...

sucker
lens
ear
neural plate ectoderm

lateral plate mesoderm
tail mesoderm

notochord
somatic mesoderm

Fig
...
3
...
Fate map of frog blastula

Neurulation
neural canal
notochord
brain
pharynx
liver

anus
digestive tract
yolk

coelom
Fig
...
3
...
Neurula of frog

The process of neurulation is the formation of a neural tube
...

During neurulation the embryo lengthens along the anteroposterior axis
...
The presumptive
area of the nervous system gets differentiated from the rest of ectoderm
...
The neural plate later thickens
and it gets raised above the general level as ridges called neural folds
...
The neural groove deepens inside
...
The neural groove gets converted into a neural tube
...
The
neural tube remains as the prospective nervous system
...

212

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

164

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

166

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
...

169

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
...

170

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 skin colour is due to the pigment
...
The number of facial bones are
a) 26

b) 25

c) 14

d) 22

5
...
Choose the flat bone in our body
...
The number of thoracic bones are
a) 5
c) 7

b)12
d) 1

8
...
The broadest muscles are named as
a) deltoid

b) gracilis

c) longus

d) lattismus

10
...
The major breathing movement is due to
a) scalene

b) thoracic

c) diaphragm

d) intercostals

12
...
The human dentition is
a) heterodont

b) thecodont

c) diphyodont

d) all the above

14
...
8 m

c) 9 cm

d) 25 cm

15
...
Breathing process can be interfered with due to
a) closure of the ileo-colic valve

b) enlargement of the tonsil

c) closure of pyloric sphinctes

d) vibration of the vocal cord

17
...
Vaso-dilation and vaso-constriction are caused by
a) tunica intima

b) exchange vessels

c) tunica media

d) tunica adventitia

19
...
The exchange vessels are
a) arteries

b) arterioles

c) Venules

d) Capillaries

21
...
The synapses are formed between
a) nerves and muscles

b) nerve tissues

c) capillaries

d) organs

23
...
The number of human cranial nerves is
a) 12 pairs

b) 31 pairs

c) 10 pairs

d) 11 pairs

25
...
The interoccular pressure is maintained by
a) aqueous humor

b) vitreous humor

c) cerebro spinal fluid

d) lymph fluid

174

27
...
The average weight of human thyroid gland is
a) 10 gms

b) 20 gms

c) 500 gms

d) 20 kg

29
...
The bunch of capillaries in the Bowman’s capsule forms the
a) medullary rays

b) calyces

c) glomerulus

d) capillary endothelium

31
...
The ovary of the foetus at 5 months gestation has
a) 40,000 Oocytes

b) 7 million Oocytes

c) 400 Oocytes

d) No Oocytes

33
...
The uterine tubes are otherwise called as
a) ureters

b) spermiducts

c) fallopian tubes

d) birth canal

175

Part - II
1
...
What is callus ?
3
...
What is a synovial joint ?
5
...

6
...
What is acetabulm ?
8
...

9
...
Write a short note on the structure of the cardiac muscle
...
Name the muscles which are essential for the movement of the neck
...
Provide the human dental formula
13
...

14
...

15
...

16
...
What is carina ?
18
...
What is double circulation ?
20
...

21
...
What is the role of B-lymphocytes ?
23
...
What is a neuromuscular junction ?
25
...
What is melbomian gland ?
27
...
What are podocytes ?
29
...
What is an eardrum ?
31
...

32
...

33
...
What is corpus luteum ?
35
...
Draw the different layers of the skin and label the parts
...
Give an account of the nail and its structure
3
...
Describe the structure of a typical long bone
...
Describe the various types of joints
...
Give an account of the muscles of the lower limb
7
...

8
...
Describe the structure of stomach with diagram
...
Explain the structure of the larynx with diagram
...
Describe the paired and unpaired cartitages of larynx
12
...
Describe the types of the blood vessels
...
Draw a neat labelled sketch showing the internal structure of the heart
15
...
Explain

a) Lymph nodes
b) Tonsils

177

17
...

18
...
What is the structure of a peripheral nerve ?
20
...
Draw a neat labelled sketch of the C
...
of human eye
...
Explain the structure of the inner ear
...
Describe the structure of the thyroid gland with diagram
...
Describe the endocrine nature of the pancreas
25
...
Explain the various stages of the Ovarian follicles
...
Describe the Ovarian structure with diagram
...
Give an account of corpus luteum
Part - IV
1
...

2
...
Explain the same with a neat diagram
...
Write an essay on the structure and organization of the axial skeleton in
human beings
...
Explain the appendicular skeleton with diagram
...
Name the muscles of the upper limb and explain how they work
...
Give an account of the organs of digestion in the buccal cavity
...
Describe the structure of digestive system with diagram
...
Explain the structure of respiratory system with diagram
...
Write an essay on structure and types of blood vessels
10
...

11
...

12
...
Explain the structure of human urinary system with diagram
...
Describe the structure of a nephron with diagram
...
Give an account of the structural organization of the hypophysis
16
...

17
...

18
...

Label the diagrams

179

4
...
0
...
It deals with the transmission of characters, specific for that particular type of plant or animal, from
the parent to the offspring of the next generation
...
It began ten thousand years ago, when human beings changed
from a nomadic life to the life of settlers
...
A need for food forced them to explore nature and
adopt agriculture
...
They learnt to identify plants that could be grown and cultivated
...
They started selecting suitable varieties for agriculture
...
Many animals
were brought under human control
...
Hybridisation and generation of new varieties of animals like
horses, dogs, cats and cattle happened
...

A scientific approach to understand inheritance was initially made by
Gregor Mendel
...
He applied statistical methods to
biological research
...
The advancement in cell biology, microscopy, biochemistry and
other disciplines provided the necessary infrastructure for this science to reach
its climax
...
Through the developments in Genetic Engineering, Biotechnology, Tissue culture and other methods we are trying to exploit nature
...
In such a safeguarding the science of Genetics
with all its related fields will play a key role
...
1 Multiple Alleles
According to Mendelism, a genetical character is controlled by the
180

combined action of two genes or factors in the same loci of two homologus
chromosomes
...
Of these two, one is
dominant and the other recessive
...
There
are many examples for multiple allelism
...
Skin colour in rabbits
Rabbits have five kinds of skin colour, coloured (agouti), chinchilla,
himalayan albino and albino, light grey
...
Himalayan albino will have pink eyes, white coat colour and
black colour in tips like nose, tail and feet
...
4
...
1
...

Parents

CC
(coloured)

x

ca ca
(albino)

F1

Cc a
(coloured)

x

Cc a

F2

CC
25%
(coloured)

Cc a
50%
(coloured)
181

c ac a
25%
(albino)
...

Other possible crossings are
Parents

CC
(coloured)

x

ch ch
(Himalayan albino)

F1

Cc h
(coloured)

x

Cc h

F2

CC
25%
(coloured)

Cc h
50%
(coloured)

c hc h
25%
(Himalayan albino)

Parents

x
c hc h
(Himalayan albino)

ca ca
(albino)

F1

x
chc a
(Himalayan albino)

c hc a

F2

chc a
c hc h
25%
50%
Himalayan albinos Himalayan albinos

c ac a
25%
albino

The above crossings show that the genes C, ch and ca representing
coloured, himalayan albino and albino are alleles of each other
...
The
coloured character is dominant over chinchilla
...
The occurrence of light grey colour is due to
partial expression of the gene for chinchilla in a heterozygous state
...
ABO blood groups in human beings
The ABO blood group system in human beings was established by K
...
It is based on the presence or absence of certain antigens
...
These are called ABO blood groups or Landsteiner blood
groups
...

The blood of a person having A group will have the antigen A and a
person having B group will have the antigen B
...
The
antibodies in a particular individual will be found only for those antigens which
are absent in blood of this individual
...
Similarly the antibody in blood ‘group B’ will agglutinize
red blood corpuscles of the blood group A
...
‘Group O’ will have antibodies for ‘group A’ and B
...

Compatibility of donor blood to that of the recipient will occur as follows
...
‘Group O’ is universal donor
...
Alleles IA and IB code for the enzymes involved in the formation of the
antigens A and B respectively and the allele ‘I o’ for no known protein
...
Both IA and IB are dominant to the recessive allele Io
...
By knowing the blood groups of parents, it is
possible to determine the possible blood groups in the children
...

Parents
OxO
OxA
OxB
O x AB
AxA
AxB
BxB
A x AB
B x AB
AB x AB

Blood group in progeny
O
O, A
O, B
A, B
A, O
A, B,AB, O
B, O
A, B, AB
A, B, AB
A, B, AB
184

Impossible blood groups
A, B, AB
B, AB
A, AB
O, AB
B, AB
None
A, AB
O
O
O

Rh blood group
Rh factor in blood was discovered by Landsteiner and Wiener in
1940
...
The human beings whose blood will get agglutinated with rabbit serum were designated as Rh +, and whose blood if not agglutinated were designated as Rh -
...

The presence of Rh+ child in the uterus of the Rh - mother can cause
agglutination in the blood of the fetus
...
The death of the foetus in such cases is due to haemolytic anemia
...


4
...
Quantitive inheritance :Charles Darwin while working on his theory of Natural selection,
recognised two principal types of variations, namely continuous and discontinuous
...
The discontinuous variations would appear all of a sudden and show no gradation
...
For example, when tall and dwarf plants were
crossed, in F1 only tall plants appeared
...
Mendel discarded intermediate characters if any, seen
...
He tried
to find an answer for its origin
...

Thus in the begnning of the 20th century two groups of geneticists
emerged
...
While the
mendelians considered that all hereditary differences are discontinuous and
qualitative, the biometricians belived that hereditary variations are basically
continuous and quantitative
...
Later,
Johansen (1903), through his work on bean seeds proved that both the views
of mendelians and biometricians were only partly correct
...

Later on, such genes were called as polygenic systems
...


Multiple factors
Skin colour in human beings
The inheritance of skin colour in black and white populations in United
States of America was worked out and reported by C
...
Davenport in
1913
...
They have intermediate skin colour in the
first generation
...

If the skin colour is due to genes in two loci A and B, the genotype of
black and white persons will be AABB and aabb respectively
...
However the F2 generation has yielded five or
more shades of skin colour
...
The effect of these genes may be further
modified due to modifying genes
...
For example, in human beings several different gene loci are
involved in determining characteristics such as body height and body mass
...
The data are to be analysed employing several biostatistical and biomathematical tools
...


4
...
Sexual reproduction is a
strategy for the production of diversity in nature
...
In this natural system, the
sex cells and the basic reproductive organs are the primary sexual characters
...

Thus the characteristic differences between male and female animals constitutes sexual dimorphism
...
These genetical methods vary in different animals
...
Sex Chromosome mechanism
The chromosomal basis for the determination of sex was first proposed by Clarance Mc clung in 1902
...
He reported that while the somatic cells of
the females had 24 chromosomes the males had 23 chromosomes
...

By further studies it was concluded that in dioecious organisms there
are two types of chromosomes
...
The other
type of chromosomes concerned with sex determination were called sex chromosomes (X and Y)
...
The cytological studies have shown that X-chromosomes in most
cases are straight, rod-like and slightly longer
...


Types

Sub types

Sex
chromosomes

Organisms
Plants like
Vallisneria spiralis
Bugs and grasshoppers

Females-2X
Males - XY

Man, other mammals
Drosophila certain
angiosperms

ZO -ZZ
Heterogametic
females

Females-2X
Males - 1X

XX - XY

Heterogametic
males

XX - XO

Females-1Z
Males - 2Z

Moths and butterfiles

Females-ZW
Males - 2Z

Gypsy moth fishes,
reptiles, birds, mammals

ZW - ZZ

187

Based on sex chromosomal determination of sex, there may be two
types of organisms, namely 1
...
Heterogametic females
...
The males have only one x-chromosome
...
, one type having
‘X-chromosomes’ and the other without ‘X-chromosome’
...
The females can produce only one
type of gametes ie
...
Hence the
female could be called the homogametic sex
...

B
...
Studies on
intersex and supersex indicated the operation of still more a complex mechanism for the determination of sex
...
It was first described by C
...

In Drosophila it was discovered that the sex of an individual depends
upon the ratio of x chromosomes to the autosomes
...
Each x chromosome carries factors with a female determining value of one and a half (1
...
Hence in a normal male (AAXY), the male
female determinants are in the ratio of 2 : 1
...
Thus the genic balance is in favour of maleness
...
Therefore the balance is in favour of femaleness
...
4
...
1
...
The cleaned sand should be spread evenly in the tank
bottom
...

Quality of water for Aquarium tank
Rain water free from contaminants or tap water is ideal for aquarium
tanks
...
This water may be stagnated for about one or two days before
use
...
The tank should be filled
with the desired water without disturbing the bottom sand
...
The plants provide shade, shelter and sanctuary for fish
...
The plants provide oxygen through photosynthesis
...

Several types of plants are available
...
Before
planting, the plants must be washed well otherwise disease causing parasites
may attack the fish at a later stage
...
1
percent solution of alum (Potassium aluminium sulphate) followed by a good
washing in water
...
The plants are
carefully installed using a forked wooden piece
...
The floating plants may be necessary in tanks where gouramies
are bred
...

Lighting : Light besides beautifying the aquarium helps in the photosynthesis
of aquarium plants
...
Further the
light is known to influence the growth of fish
...
For a moderate tank two bulbs of 60 watts
each may be lit for eight hours a day
...


240

Common ornamental fishes
Live bearers
Guppy

-

Lebistes reticulatus

Platy

-

Xiphophorus maculatus

Sword tail

-

Xiphophorus helleri

Black molly

-

Mollienesia sphenops

Egg Layers
Siamese fighter - Betta splendens
Giant gourami - Colisa fasciata
Kissing gourami - Helostoma temmineki
Angel fish - Pterophyllum scalare
Gold fish - Carassius carassius

Siamese fighter

Angel fish
Sword tail

Guppy

Gold fish

Fig
...
1
...
Ornamental fishes

241

The male is very small and microscopic
...
The males normally live as parasites attached to females
...
However a larva settling on the
proboscis of an adult female becomes a male individual
...
, in the absence of a female) it develops into female
...

From these observations it could be inferred that the proboscis of adult female
secretes some hormone like substance and that substance suppresses femaleness and induces maleness in the larvae which remains attached
...
4 Sex - linked Inheritance
Most of the inheritable characters are controlled by genes located in
autosomes
...
Mendelian ratios are not obtained for those characters for
which genes are exclusively located either in X or Y chromosome
...
Similarly,
that the genes occur exclusively on Y chromosomes are called the holandric
genes
...
Thus the sex linked inheritance may be X- linked, Y- linked or XY
linked
...
H
...
He found that the gene for
white eye colour is X - linked
...


Red eyed female x white eyed male
When a wild red eyed female Drosophila is crossed with a mutant
white eyed male, all the F1 individuals (males and females) have red eyes
...
Among the
males 50 % had red eyes and another 50 % had white eyes
...
When these red eyed female individuals and white
191

eyed male individuals of F1 are intercrossed the F 2 generation possessed 50 %
red eyed and 50 % white eyed females
...

Red eyed female

White eyed male

Parents
Red eyed female

Red eyed male

F1

Red eyed female

Red eyed female

Red eyed male White eyed male

F2

Fig
...
4
...
Drosophila - Red eyed female x White eyed male

Sex linked inheritance in Humans
Most of the sex linked characters in humans are X - linked
...
Most of them are recessives
...
The cone cells are sensitive to red, green and violet
light
...

The recessive form of this gene is incapable of producing colour sensitive cones
...

The frequency of colour blind women is less than colour blind men
...
However the female will be a carrier for the
recessive gene
...


4
...
This finding is not always true
...

This phenomenon of multiple effects of a single gene is called pleiotropism
...
If the gene causes other less conspicuous
phenotypic changes, it is known as secondary effect
...

Vestigeal wings in Drosophila are caused by a recessive gene
in homozygous condition
...
They are (i) the small halters or balancers behind the wing
(ii) structure of reproductive organs (iii) egg production (iv) life duration and
(v) bristles on the body
...
They were able to identify a dominant
trait namely brachydactyly that agreed with the Mendelian theories and showed
Mendelian ratio in the human populations
...

An objection to this example was raised
...
But in reality brachydactyly is seen rarely in
human population
...
However, until 1908 it remained unexplained among the
scientists
...
E
...
This theory explains
why some characters though dominant (like brachydactyly) appear rarely in a
population
...
4
...
1
...
It simply means, that the
common traits remain common and the rare traits remain rare
...
The relative abundance of a genotypye in a
population is referred to as its genotypic frequency
...
4
...
2
...
‘A’ remains dominant to ‘a’
...
Then the number of individuals (or frequency) with AA is ‘p’ and the
number of individuals with ‘aa’ (or frequency of aa) is ‘q’
...
As both the characters are considered as
homozygotes the individuals with AA will produce all gametes with ‘A’
...

If all the gametes are viable, combine at random, all have the chance
of survival and no new gametes are introduced in to the population, we can
calculate the proportion of next generation with genotype AA using the usual
Punnet Square method
...

Problems: This could be proved mathematically p + q = 1 on both sides
...
Here each side of the
square represents one unit
...
The points are chosen randomly
...
The area of each rectangle
represents the frequency of the resulting progeny (or) the proportion of the
next generation having the genotype specified in each cell
...
00 (or) 100% of the
population
...

195

Substitute these values for the symbols p and q and find out the percentage of
heterozygotes found in the population when it reaches the equilibrium
...


p = 40% , q= 60%
p + q = 1 or 100
i
...

It is clear that this law is applicable only to populations with following
features
a) Infinitely large populations
b) No mutation
c) No selection
d) Random mating
e) Isolated from any other population of the same species
...
Such populations
that has reached equilibrium remain unchanged from generation after
generation
...

1
...
Assume that brown eyes are dominant to blue eyes
...
What proportion of the population is
heterozygous
...
The skin colour agouti in rabbits has the genotype
(a) CC

(b) Cca

(c) Cc h

(d) all the above
...
The alternative forms of a gene are
(a) allelomorphs
(c) heterozygous

(b) multiple alleles
(d) homozygous
...
The universal recipient is
(a) ‘O’ Group
(c) ‘A’ Group

(b) ‘AB’ Group
(d) ‘B’ Group
...
ABO blood group in man is an example for
a) Pleiotropism

b) multiple allelism

c) x - linked inheritance

d) y - linked inheritance

5
...

(a) Yule
(c) Galton

(b) Mendel
(d) C
...
Davenport
...
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

8
...
The poly ‘X’ females are
(a) super females
(c) bisexuals

(b) hermaphrodites
(d) intersex

10
...
Most of the sex linked characters in humans are
(a) Y-linked
(c) X linked

(b) XY linked
(d) all the above
...
X/A ratio in super females is
a) 1
...
0

c) 0
...
5

13
...
The genotypes better adapted for malaria is
(a) HbA HbA

(b) HbA HbS

(c) HbS HbS

(d) all the above

15
...

1
...
Provide the genotypes for himalayan albino rabbits
3
...

4
...
What was the opinion of the biometricians as geneticists?
6
...
What is Hermaphroditism?
8
...
What are holandric genes
...
What are modifying genes
...
What are secondary sexual characters?
12
...
Write down the symptoms of Turner’s syndrome
...
Explain multiple factor hypothesis
...
Differentiate a normal RBC from a diseased RBC
...
What will be the nature of the F 2 progeny, if a coloured rabbit is crossed with
an albino?
2
...

3
...


199

4
...
Write notes on quantitative inheritance
...
Provide an account on turner’s syndrome and klinefelter’s syndrome
...
Describe the process of sex determination in Bonellia
Part - IV
Answer in detail
1
...

2
...

3
...

4
...


200

5
...
A zygote is a single celled
structure
...
These phases
include cleavage, gastrulation, neurulation, organogenesis and the period of growth and histological differentiation
...
Till later stages of development a fundamental uniform pattern in
development can be observed
...

Realising the mode of formation of a young individual of the next generation has always interested human mind
...
The
‘Susruta samhita’, a monumental Indian medical book, written during
second or third century A
...
, describes the development of a human child in
the mother’s womb
...

His classical work De Generatione Animalium is concerned with the generation of animals
...
In his another work “De Historia Animalaium”, Aristotle
provides an account of the development of the hen’s egg
...
By observing the development of hen’s egg he concluded that the
development always proceeds from simple formless beginning to the
complex organization of the adult
...
Through his remarkable observation and speculations
Aritotle established ‘embryology’ as an independent field in science
...

After the period of early Greek thinkers this discipline once again got
the attention of the scientists from the beginning of the 17 th century
...
Haeckel, O
...
B Wilson, Spemann, C
...
Modern embryology has utilised all tools
made available from other branches of science and diversified into branches
such as ‘Experimental embryology’, ‘Chemical embryology’, ‘Comparative embryology’ and Descriptive embryology
...


Gametogenesis :
The process of embryonic development in sexually reproducing
multicellular organisms is made possible through processes of
gametogenesis and fertilization
...
It happens in primary sex organs
called gonads
...
These cells are responsible for the production of gametes
...
5
...
1
...
The primordial
germ cells of these tubules produce cells which ultimately become sperm
202

mother cells or spermatogonia
...
These are diploid cells
...
Initially the I Meiosis results in the formation of
secondary spermatocytes
...
The
spermatids are haploid in nature
...


Oogenesis :
A similar process happens inside the female gonad, namely the ovary
for the production of Ova
...
These stages are conducted by meiotic cell divisions
...


Fertilization :
Embryogenesis could occur only after the fertilization of the ovum or
egg
...
Thus all the somatic
cells of the embryo will remain diploid
...
During the process of
fertilization the sperm and ovum of the same species approach and come in
contact with each other
...
The haploid nuclei of the sperm and ovum fuse, resulting in the formation
of a diploid zygote nucleus
...


5
...
Types of eggs
For the embryo to develop inside a fertilised egg nutrition is needed
...
It normally
depends on the duration of development
...

It may be ‘fatty yolk’ or protein yolk’
...
Due to accumulation of yolk a maturing egg rapidly
increases in size
...
Chemically, the yolk platelets contain two main proteinaceous substances namely phosvitin and lipovitellin
...
The amount of yolk influences cleavage and
gastrulation methods
...


Amount of yolk and egg types :
In certain animals the developmental stages are not very elaborate
...

Such conditions remain in animals like Hydra, Sea urchin, Amphioxus and
Placental mammals
...
Such eggs are said to be
Microlecithal or oligolecithal
...
Hence for such eggs the amount of yolk is considerable in quantity
...
Such eggs are produced by annelid worms, molluscs and amphibians
...
The growth period is sufficiently long
...
Such eggs
are termed as Megalecithal or Macrolecithal eggs
...
Further these eggs are covered by
a calcareous shell
...

Such eggs are called cleidoic eggs or land eggs
...
5
...
2
...

The pattern of cleavage and the consequent gastrulation processes
are affected by the distribution of yolk within the egg
...

204

1
...

Eggs of this type have the yolk disbursed in the entire cytoplasm
...
5
...
3
...
In such eggs the cleavage will be deeper and may bisect the eggs
connecting the two poles
...

2
...


animal pole
nucleus

yolk
vegetal pole
Fig
...
1
...
Telolecithal egg

All eggs have polarity
...
The polar
nature is mainly due to the denser material in the cytoplasm, namely yolk
...
The
cytoplasm with the nucleus will occupy the upper animal pole
...
Thus the eggs having a
polarised distribution of yolk in the cytoplasm are referred to as Telolecithal
eggs
...

3
...


cytoplasm
shell

•
Fig
...
1
...
Centrolecithal egg

205

yolk
nucleus

An egg need not be spherical always
...
The pattern of cleavage and further gastrulation also
deviate from that of the vertebrates
...
However, the eggs of echinoderms
are similar to that of the vertebrates
...
2 Cleavage and types - Frog’s egg
...
It is
initiated by the sperm during fertilization
...

The process of cleavage or cellulation happens through repeated mitotic divisions
...
In later
stages of development the blastomeres occupy different regions and differentiate into several types of body cells
...
The entire process of cleavage in frog’s egg was studied by Prevost
and Dumas in 1824
...

From all these studies it has become clear that all divisions in cleavage
are mitotic
...
In the eggs of sea urchin division of the blastomeres can be observed every 30 minutes
...
During cleavage there is no growth in the blastomeres
...
The cleavages result in a compact mass of blastomeres called morula
...

While the wall of the blastula is called the blastoderm, the central cavity is
called the blastocoel
...
Depending on the position of the cleavage furrow the planes of cleavage are
named
...
Meridional cleavage: The plane of cleavage lies on the animal vegetal
axis
...
Thus the egg is divided into two equal
halves
...
Vertical cleavage: The cleavage furrows may lie on either side of the
meridional plane
...
The cleaved
cells may be unequal in size
...
Equatorial cleavage: This cleavage plane bisects the egg at right angles
to the main axis
...
It divides the egg into two
halves
...
Latitudinal cleavage: It is similar to the equatorial plane, but it lies on
either side of the equator
...

Influence of yolk on cleavage
Yolk is needed for embryonic development
...
Somehow with all the influences of yolk the
developmental procedures are so adapted and modified that a well formed
embryo will result
...

The amount of the yolk and its distribution affect the process of cleavage
...

1
...
Such a cleavage may be either equal or unequal
...
Eg: Amphioxus and
placental mammals
...
Among the
blastomeres there are many small sized micromeres and a few large sized
macromeres
...
Meroblastic cleavage - In this type the cleavage furrows are restricted to
the active cytoplasm found either in the animal pole (macrolecithal egg) or
superficially surrounding the egg (centrolecithal egg)
...

(a) Discoidal cleavage - Since the macrolecithal eggs contain plenty of yolk,
the cytoplasm is restricted to the narrow region in the animal pole
...
Such
a cleavage is called discoidal meroblastic cleavage
...

207

(b) Superficial cleavage - In centrolecithal eggs, the cleavage is restricted to
the peripheral cytoplasm of the egg
...

Laws of cleavage
Apparently there are several cleavage patterns
...
The cleavages are governed by certain
basic principles or laws
...
Sach’s laws - These laws were proposed by Sach in 1877
...

2
...

Cleavage of fertilized egg in Frog
...
The cleavage
occurs as follows
...
S

blastula-entire

Fig
...
2
...
Cleavage in frog’s egg

1
...
Initially, a furrow appears at the
animal pole
...
It cuts
the egg through its median animal-vegetal polar axis and results in two equalsized blastomeres
...
The second cleavage furrow is again meridional
...
It is a holoblastic cleavage affecting both the
blastomeres of the first cleavage
...

208

3
...
Such a furrow is due to the influence of yolk
concentration in the vegetal pole
...
It results in the formation of eight blastomeres
...
They are named as macromeres
...
They are named as
micromeres
...

4
...
They are
unequal
...
These cleavages result in the production of 16 blastomeres
...
As a result of further cleavages, a ball of several small blastomeres result
...
The larger blastomeres are called the macromeres
...
5
...
2
...
S of Frog blastula

At the final stages of cleavage the embryo acquires a characteristic,
mild, oblong shape
...
The morula initially
contains a shallow cavity called the blastocoele
...
However the blastocoele mostly remains in the animal pole region in the middle of
the micromeres
...
The blastoderm remains
two cell thick in the animal pole
...

It has been reported that around 12th cleavage the blastula possesses
about 4096 cells
...

The ultimate blastula is a ball of blastomeres which have to form different embryonic body layers and organs of the body
...
A map showing various
209

organ forming, areas on the blastula is called the ‘fate map’
...
It also shows the
‘zone of involution’ and ‘zone of invagination’ for the next stage of gastrulation
...
3
...
During this process the blastodermal cells begin to move
...
During this movement at
one region on the blastula, the cells wander inside and occupy the blastocoelic
cavity
...
They move toward the interior of the blastula
...
A deepening of the
invagination results in a cavity called the archenteron or gastrocoel
...

The blastopore gradually assumes a crescentic shape
...
The region dorsal to the blastoporal opening is called the ‘dorsal lip’
...

dorsal lip

Fig
...
3
...
Formation of dorsal lip

The surface cells representing several prospective zones of the embryo begin to wander inside through the blastopore
...

blastoderm

blastocoele

dorsal lip of blastopore

invagination of macromeres

Fig
...
3
...
Invagination of Endodermal cells

210

Initially, the first pharyngeal endodermal cells undergo invagination over
the dorsal blastoporal lip
...
They are followed
by other cells
...
Thus the blastocoelic cavity gets reduced
...
It is called the gastrocoel
...
The interior region of the archenteron gradually transforms into the pharyngeal region
...
The
mesodermal and endodermal cells gradually occupy their positions
...
The involution results in the positioning of chordamesodermal cells and pharyngeal endodermal cells
...
5
...
3
...
While the exterior chorda-mesodermal cell involute inside, their place is taken up by the ectoderm
...
Epiboly causes overlapping or ‘the roofing over’
of the gastrula by the ectoderm
...
The
closing cells of the blastopore constitute the yolk-plug
...


211

The process of gastrulation converts the blastula into a spherical, bilaterally symmetrical, triploblastic gastrula
...

sucker
lens
ear
neural plate ectoderm

lateral plate mesoderm
tail mesoderm

notochord
somatic mesoderm

Fig
...
3
...
Fate map of frog blastula

Neurulation
neural canal
notochord
brain
pharynx
liver

anus
digestive tract
yolk

coelom
Fig
...
3
...
Neurula of frog

The process of neurulation is the formation of a neural tube
...

During neurulation the embryo lengthens along the anteroposterior axis
...
The presumptive
area of the nervous system gets differentiated from the rest of ectoderm
...
The neural plate later thickens
and it gets raised above the general level as ridges called neural folds
...
The neural groove deepens inside
...
The neural groove gets converted into a neural tube
...
The
neural tube remains as the prospective nervous system
...

212

During neurulation, the tubulation of chorda-mesoderm and tubulation
of endoderm also happen
...
5
...
6
...


5
...
Organogenesis of Frog
The primary organ rudiments from ectoderm, mesoderm and endoderm get well established during the processes of gastrulation and neurulation
...
These rudiments get differentiated into various organs and
organ systems
...


Epidermal ectoderm
The epidermal derivatives are the skin, olfactory sense organs, ear,
lateral line sense organs, median fins, external gills and lining of mouth and
anus
...


Development of eye
The eye is a photoreceptor
...
Its
development begins even at the gastrulation stage
...

Formation of optic cup
The eyes develop as two lateral outgrowths of the prosencephalon
called optic vesicles
...
The
connection of the optic vesicle with the brain becomes a narrow stalk like
structure called optic stalk
...
The optic vesicles
extend outward and reach the ectoderm
...

The optic cup consists of two layers
...
The outer layer will
be a thin, black pigmented layer (tapetum - nigrum) for the absorption of
light
...
Soon its rim bend inward and
converges, so that the opening is reduced
...

The rim of the optic cup surrounding the pupil becomes the iris
...
A
groove extends along the ventral side of the optic cup
...
It extends to the middle of optic stalk
...

The retina develops a membrane on its inner most surface called the
internal limiting membrane
...
The inner cells of the retina differentiate
into neuroblasts or nerve cells
...
This is called
the lens placode or lens rudiment
...
The free edges of the cup fuse to form a globular
hollow lens vesicle
...

The cells of the inner side of the lens vesicle elongate, become
columnar and are finally transformed into long fibres
...
These cells
are called lens fibres
...
The junction between the lens fibres and the
lens epithelium represents the growing point of lens
...

When the lens is formed, the free margin of optic cup touches the
edges of the lens and grows in front forming iris
...

Soon after the development of lens the overlying ectoderm closes
over and differentiates to become the cornea
...

The transformation of the skin into cornea is caused by an induction arising
from the optic cup and lens
...
This is known as conjunctiva of the
eye ball
...

The space between lens vesicle and the overlying presumptive
anterior epithelium of cornea represents the anterior chamber
...

The choroid and sclerotic coat of eye develop from the mesenchyme
cells accumulating around the eye ball
...
The outer layer of mesenchyme form
fibrous capsule, the sclerotic coat or sclera around the eye
...

215

The ectoderm from above and below the original lens placode region
grows out as two folds
...
At a later stage
these folds separate along the line of fusion to form the regular upper and
lower eye lids
...
5
...
1
...


Development of heart in Frog
The heart is the first organ to start functioning because it has to
circulate blood which brings nourishment from the endodermal cells to the
other parts of the embryo
...
The first
rudiment of heart develops after neurulation in the region beneath the
pharynx, from the mesenchyme and mesoderm
...
It is formed
by mesenchyme cells
...
Soon the endocardial cells get arranged in the form of a
thin walled tube, the lumen of which later develops into the cavity of the
heart
...
The visceral layer of
mesoderm envelops the endocardial tube and gives rise to its muscular walls
or myocardium and also its close fitting covering called the visceral
pericardium
...
Its wall is formed of three layers, outer epicardium, middle
myocardium and inner endocardium
...

The tubular heart elongates rapidly in antero-posterior direction
...
The
increase in size causes the originally straight tube to curve and fold forming217

S- shaped coiled tube
...

At the same time different regions of the tube grow differently in
thickness and constrictions appear demarcating different presumptive
chambers of the adult heart
...
This is followed by a thin
walled atrium which opens infront into a thick walled ventricle
...
Later on, a partition grows
downward from the dorsal wall of the atrium dividing it into larger, right and
smaller left atrial chambers
...
As the
septum is developed on the leftside of the opening of the sinus venosus, the
sinus venosus communicates only with the right auricle
...
The valves of the heart arise as folds of endocardium
...
5
...
2
...
5
...
3
...

Self Evaluation
Part - I
Choose the right answer
1
...
Hertwig

(b) E
...
B
...
The process of spermiogenesis involves
a) production of sperms
b) differentiation of spermatids into spermatozoa
c) formation of testis
d) differentiation of nucleus
3
...
In amphian eggs yolk occurs in the form of
(a) yolk platelets
(c) phosvitin

(b) blood platelets
(d) lipovitelline

5
...
Superficial cleavage is seen in
(a) amphibians
(c) reptiles

(b) insects
(d) birds

7
...
Sach’s law is related to
a) gametogenesis

b) cleavage

220

c) gastrulation

d) organogenesis

9
...
The embryo having a fluid -filled cavity and a layer of cell is called
(a) blastocoel

(b) blastula

(c) morula

(d) blastoderm

11
...
The heart is derived from
(a) ectoderm

(b) mesoderm

(c) endoderm

(d) all the above

13
...
The valves of the heart arise as folds of
a) myocardium

b) epicardium

c) endocardium

d) pericardium
Part - II

Give very short answer
1
...
Why do we consider Aristotle as the founder of the science of embryology?
3
...
What are microlecithal eggs?
5
...

6
...
What is a morula?
8
...

9
...

10
...


221

11
...
What is a ‘fate map’ ?
13
...

14
...
What is a gastrula?
16
...
Define tubulation?
18
...
Name the organs developed from the mesoderm?
Part - III
Answer briefly
1
...

2
...
Provide a general account on cleavage
...
Give an account of the planes of cleavage
...
Explain the process of equal and unequal holoblastic cleavage
...
What is sach’s law?
7
...

8
...

9
...

10
...
Provide a detailed account on the types of eggs
...
Give an account on the cleavage of fertilized egg
...
Give a detailed account of the cleavage in frog with neat diagrams
...
Describe how the process of gastrulation occurs in the egg of an amphibian
5
...

6
...

7
...


222

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
...

223

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
...

224

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
...

225

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
...

227

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
229

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
230

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
...

231

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
...


233

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
239

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
...

242

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

244

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
245

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

251

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

253

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
256

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

258

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
...


6
...
Regeneration studies in Planaria
Tissue culture, nuclear transplanting, stem cell research, tissue
response to hormones are all recent interesting experimental fields in
biology
...
These inquisitive studies have paved the way
for applicability of biological knowledge towards human welfare
...
The animals possess the ability to repair extensive damages
259

incurred by the body either accidentally or in natural conditions
...
The capacity to regenerate lost parts differs
in various groups of animals
...
As the organization of animals becomes advanced
the capacity for regeneration gets restricted
...

Mammals can regenerate blood cells
...

Among multicellular and triploblastic animals the Planarians are
remarkable for their high regenerative ability
...


→

→

→

→

→

→

→

→
→

→

260

Fig
...
3
...
Regeneration experiments in planaria

Mechanism of regeneration
The process of regeneration happens through epimorphosis and
morphallaxis
...
This process is termed as epimorphosis
...
This reorganization is called as morphallaxis
...
A knowledge of all factors and
the mechanisms of regeneration even to-day remain as potential fields for
further research, study and application
...
Reef forming corals normally grow in
(a) cold waters

(b) deep seas

(c) shallow, tropical seas

(d) polluted and muddy waters

2
...
The larva of corals is a
(a) trochophore

(b) planula

(c) medusa

(d) polyp

4
...
The coral used in jewellery making is
(a) Corallium nobile

(b) Tubipora

(c) Organ pipe

(d) Guano

6
...
The degrades of organic matter by worm activity is
(a) lac

(b) isinglass

(c) vermicompost

(d) guano

8
...
The honey bee used commonly in bee-keeping industry is
(a) Apis dorsata

(b) Apis florea

(c) Apis indica

(d) all the above

10
...
The secretion from the abdominal glands of the worker bee is
(a) honey

(b) nectar

(c) beeswax

(d) all the above

12
...
Assam is famous for

262

(a) Muga silk

(b) Eri silk

(c) Tasar silk

(d) Mulberry silk

14
...
The predatory insects are said to be
(a) entomophagous

(b) larvivorous

(c) parasitic

(d) pests

16
...
The organization involved in pearl oyster culture is
(a) CIBA

(b) CMFRI

(c) NIO

(d) MPEDA

18
...
The name Kal Eral in Tamil refers to
(a) Prawns

(b) crabs

(c) a fish

(d) lobsters

20
...
Fish meal is used as in
(a) animal feed

(b) manufature lubricants

(c) preparation of cakes

(d) all the above

22
...
Gold fishes are the varieties of the genus
(a) Xiphophorus

(b) Betta

263

(c) Carassius

(d) Lebistes

24
...
Which country was economically benefitted by marketing bird excreta
(a) USA

(b) Peru

(c) Australia

(d) West Indies

26
...
The idea of aquarium maintenance was first conceived by
(a) Chinese

(b) Japanese

(c) Red Indians

(d) Africans

28
...
Nandankanan Biological park is situated in
(a) Delhi

(b) Orissa

(c) Bihar

(d) Assam

30
...
The filarial worms attain sexual maturity in the
(a) human blood vessels

(b) human lymphatic vessels

(c) culex mosquito

(d) all the above

32
...
Which is the best time to have blood test for filariasis
(a) morning
(c) noon

(b) evening
(d) mid-night
264

34
...
The intestine and kidneys of the puffer fish has a dead ly poison called
(a) tetraoxin

(b) cyanide

(c) haemotoxin

(d) cystamine

36
...
Ophiophagus hannah refers to
(a) Indian cobra

(b) King cobra

(c) Russell’s viper

(d) Sea snake

38
...
The caterpillar of the butterfly causes
(a) cabbage fertilization

(b) cross pollination

(c) damage to leaves

(d) damages to roots

40
...
The silver fishes commonly live among
(a) rocks

(b) algae

(c) other fishes

(d) old books
Part II

Give very short answer
1
...

2
...
Mention the use of vermicompost
...
What are productive insects? Give an example
...
Differentiate nectar and honey
...
What are the uses of beewax
...
What is meant by biological control?
8
...
Name any two edible crabs
...
Provide the names of one live bearer and one egg layer from among the
ornamental fishes
...
Name any two fish liver oils
...
Name any two rooted plants used in aquarium
...
What are the controlling measures taken to control pests in coconut palm
...
How do the haemolytic toxins cause death in an organisms
...
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 Corallium nobile ?
20
...
Give the names of two common pests of cotton
...

2
...

3
...

How this could be achieved?
4
...

5
...

6
...

7
...

8
...

9
...
Give an account on fouling organism
...
Draw and label the poison apparatus in a snake
...

1
...
Explain
the process Vermiculture
...
Give an account of insects and insect products of commercial importance
...
What are the nutritive values of fishes
...
Give a detailed account on setting up an aquarium and maintaining the same
...
Write an essay on insect pests of stored products and household goods
...
ORIGIN OF LIFE
7
...
Theories
Origin of life
Our planet earth is inhabited by an enormous variety of living organisms
...
The diversities
mostly appear as adaptations for diverse habitats and living methods adopted
...
To a certain extent Charles Darwin’s natural selection concept provides an explanation towards an understanding of evolution of various kinds of
life forms
...

Several intelligent explanations had been provided to account for the origin of
life on earth
...
Theory of special creation
According to the proponents of this theory all living forms with their
richness in diversity were created abruptly by a super natural power
...
However, supporters of this theory have recently created a new discipline called “creation science”
...
Cosmozoic theory
This theory states that life came to earth from some other planet or
star
...

They reached earth accidentally
...
An acceptance of this theory needs
evidence for the existence of extra-terrestrial life
...
Theory of spontaneous generation or abiogenesis
The theory that life originated from non-living material is now called
abiogenesis
...
The ancient Greek philosophers like Thales, Empedocles and Aristotle supported this concept
...
According to Empedocles (540-433
BC) life originated by itself from non living matter and imperfect forms were
268

replaced by perfect forms
...
The activation was due to vital forces
or guiding intelligence
...

In the 17th century the idea of abiogenesis was opposed by an Italian
physician Francisco Redi (1621-1697)
...
He tested
his hypothesis by sealing meat inside four closed flask, while leaving another
four meat filled flasks open
...
Flies were entering and leaving the flask
...
This experiment confirmed his
idea that new life can come only from early life
...
Big Bang theory
This theory is concernced with the origin of earth and other planets
...
All matter
was created in this big bang including the matter of which stars and planets
are composed of
...
When a certain critical temperature is reached thermonuclear reactions will begin and cause a ‘big bang’
...

5
...
I
...
Oparin, a Russian chemist published a paper in 1924
...
This theory is called the “theory
of primary abiogenesis”
...
The primordial earth, about 2600 million years ago provided suitable atmosphere for the
origin of life
...
More and more complex organic compounds were formed under the
influence of electric charges and Ultra violet rays
...

6
...
B
...
Haldane’s hypothesis
Haldane was a British biochemist
...
Today’s earth
is surrounded by oxygen and its derivative ozone
...
In 1929, he
suggested that an atmosphere lacking O 2 would have no ozone layer
...
In a reducing atmo269

sphere this could have caused photochemical reactions resulting in the generation of organic molecules
...

7
...
7
...
1 Spark-charge apparatus of Stanley Miller

U
...
They conducted experiments in which a gas mixture containing
hydrogen, ammonia, methane and water vapour was subjected to electric spark
...
They visualised
the existence of a similar situation and happening of events resulting in a large
scale accumulation of diverse biomolecules in the primordial earth
...

8
...
The
tendency of biological polymers to form polymer-rich droplets called coacervates has been proposed by Oparin
...
Biochemical processes like enzyme action and electron transport can happen
within a coacervate
...


270

7
...
Geological time scale
The oldest known rocks are about 3
...

It corresponds to 38, 000, 000 centuries
...
7 billion (4,700 million) years old
...
5 billion (2,500 million) years ago
...
Such a
period in earth’s history is known as the Azoic era (2,200 to 5,000 billion
years ago)
...

Gradually the upper surface of the earth cooled down
...
Further water molecules were
formed resulting in accumulation of water and water reservoirs as water
masses and land surface were established
...

Once the life originated and established, evolutionary changes took
place
...
Thus fauna and flora started flourishing on earth
...
Later land surfaces were invaded by plants and animals
...
This period is divided into three eras
...
Of these, the oldest era was the Paleozoic era
...
Thus its duration was nearly 390 million
years
...

The Paleozoic era was followed by middle period named as Mesozoic era
...
Its duration was
145 million years
...
Hence this era is known as the golden age of reptiles
...

The period ranging from 65 million years till date is named as the
Coenozoic era
...
This era is known as the Age of mammals
...
Based on age, and events, the ancient period from
271

Era

Duration

Significane

Palaeozoic

600 - 210 m
...


Mesozoic

210 - 65 m
...


Cenozoic

65 - 1 m
...


earth’s history is formulated into eras-periods-epochs
...
Incidents pertaining
to earth surface, plant and animals life are neatly recorded
...


Era

Period

Epoch

Duration

(million years ago)

Quarternary

Pliestocene

2-1

CENOZOIC

Tertiary

Pliocene
Miocene
Oligocene
Eocene
Palaeocene

7-2
26 - 7
38 - 26
54 - 38
65 - 54

MESOZOIC

Cretaceous
Jurassic
Triassic

130 - 65
160 - 130
210 - 160

PALAEOZOIC

Permian
Pennsylvanian
Mississipian
Devonian
Silurian
Ordovician
Cambrian

235 - 210
255 - 235
275 - 255
315 - 275
350 - 315
440 - 350
600 - 440

Precambrian

440 and before

272

Periods

Events

Quarternary - Pleistocene
TERTIARY - Pliocene
TERTIARY - Miocene

2 - 1 m
...
years ago
26 - 7 m
...
years ago
TERTIARY - Eocene
54 - 38 m
...
years ago

CRETACEOUS
JURASSIC

130 - 65 m
...
years ago

TRIASSIC

210 - 160 m
...
years ago
255 - 235 m
...
years ago

DEVONIAN

315 - 275 m
...
years ago
440 - 350 m
...
years ago

PRECAMBRIAN

before 440 m
...

Carnivorous mammals
were dominant
Monkeys and apes
originated
Horses originated
First flowering plants
Mammals originated
Dinosaurs disappeared
...

Dinosaurs evolved
...

Origin of reptiles
...

Origin of Amphibia
...

Age of fishes
...

Jawed fishes originated
First vertebrates,
Jawless fishes,Bryophytes
...

Protozoans,
Poriferans and Annelids
lived
...
Paleozoic era :- This era produced revolutionary changes in the
biosphere
...

Thus this era is known as the Cradle of ancient life
...
Cambrian period :- (600 to 440 million years ago)
The period preceeding cambrian is known as Pre-cambrian period
...
Thus the cambrian started with the plants and animals that
were suceessful during the precambrian period
...
They diversified into various groups
...
Among animals the aquatic arthropods
and echinoderms came to prominence
...

2
...
7
...
1 Jamoytins - an earliest jawless fish

This period was marked by formation of coral rocks and molluscs and
echinoderms
...
Interestingly this period saw the origin of first vertebrates
...
(Jawless, armoured fishes)
...

Among arthopods, the trilobites were more prominent during this period
...
Silurian period :- (350 to 315 million years ago)
The oldest land plant originated in this period
...
They colonised the land
...
The corals diversified
...
Jawed fishes originated
...
Origin of paired fins and jaws is
considered as major events in chordate evolution
...
7
...
2 Ostracoderms - the early armoured, jawless
fishes and Placoderms - the early jawed fishes
...
Devonian Period :- (315 to 275 million years ago)
It is a significant period in the paleozoic era
...
The forests were filled with varieties of
ferns and cycas
...
Among aquatic animals fishes became dominant
...
The forefathers of almost all modern fishes lived during
this period
...

5
...
7
...
3 The Australian lung fish - Neoceratodus

Several changes happened to the land structure
...
This resulted in the formation of several
mountain ranges
...
These
major changes on earth’s surface were known as revolutions(eg
...
Such changes were the cause for the origin of lungs in fishes
...
It helped such
fishes to find new water bodies
...
The origin of land living amphibians were further increased by
the proliferation of several land living insects
...
Pennsylvanian :- (255 to 235 million years ago)
The land living forms became more successful during this period
...
Due to geotectonic changes several
forests got burried under the soil
...
Hence the Pennsylvanian and the earlier Mississippian were collectively krown as Carboniferous (carbon bearing) period
...
Permian Period :- (235 to 210 million years ago)
It was the last period in the Paleozoic era
...
Nearly 60% of the
organism that survived at that time became extinct
...
Specifically the group
of organisms that laid such eggs are identified as Seymouria
...


II
...
Among animals the reptiles became more
dominant
...
Hence this era is named as
the Golden age of reptiles
...
Triassic Period :- (210 to 160 million years ago)
For the first time fossils of turtles, crocodiles, and dinosaurs have been
obtained from this period
...
The mammals orginated from reptiles
during this period
...
Jurassic Period :- (160 to 130 million years ago)
There was a marked adaptive radiation among dinosaurs
...
The first birds originated from the
reptiles
...
The
origin of birds was a major physiological change among animals
...

The modern bony fishes were diversified into several groups
...
7
...
4 Mesozoic Birds and Reptiles

277

Cretaceous Period :- (130 to 65 million years ago)
The larger marine molluscs became extinct
...

The Dinosaurs of the Mesozoic era abruptly became extinct during
this period
...
Fossils of dinosaurs were not obtained from later periods
...
Cenozoic Era :- (65 million years ago till date)

Fig
...
2
...

All modern animals and plants were represented in these fossils
...
Further this era contains
seven epochs
...

1
...

2
...
The ancestral form of modern horses lived
during this epoch
...
Oligocene epoch :Several animals with ancient characteristics became extinct
...
The apes originated during this epoch
...
Miocene epoch :Several varieties of grasses evolved in Europe and N
...
Thus
large Priaries were formed
...
Thus the carnivorous
mammals came to prominence
...
Pliocene Epoch :The priaries enlarged still further in several regions
...
The mammals increased in number
...
Pleistocene epoch :Several glaciations happened during this time
...
The evolution of horses and man reached the
final stages during this period
...
Today we are living in an
inter-glacial Period
...
3 Fossils
The fossils are the preserved remains of animals, plants or their parts
found in various strata of earth
...


Fossilization :- Fossils can result by several methods
...
There are many methods of fossilization
...
Petrifaction :- It is the commonest method
...
This is due to formation of sedimentary rocks under water
...
The preservation happens in the original strata
...
Petrifaction of soft parts :- Under certain conditions muscles and other
soft organs may get mineralised and form rocky fossils
...

3
...
These prints, if left undisturbed, can get hardened and form rocky fossils
...

4
...
Several invertebrate fossils had been obtained as moulds
...

5
...
The dried material can get fossilized
...

279

6
...
In such fossils the body parts remain intact without change
...

7
...
It is known that all elements exist as
isotopes
...
e
...
Some isotopes remain unstable
...
Examples are
Uranium238

lead 206

Potassium 40

Calcium40+argon39

Carbon14

Carbon12

The time required for the breakdown of half the given quantity of
unstable isotope is called the half-life
...
Eg
...


Evolutionary significance of fossils
1
...
Fossil studies reveal the course of
evolution
...
Through fossils the origin and evolution of specific groups of organisms can
be understood e
...
Horse evolution
...
Fossils provide us clues regarding climatic conditions of various prehistoric
periods
...
Study of fossils simplifies phylogenetic discussions
...
Some fossils like woolly mammoth can provide vital clues regarding genetical make up
...

Seymouria - Interconnecting link between Amphibians and Reptiles
...

Hyracotherium - Early ancestor of horses
...
3 Extinct animals-mass extinction
Extinction may be defined as the termination of a lineage without issue or abrupt disappearance of specific groups of organisms without leaving
descendents
...
In true extinctions a particular lineage totally disappears without
any progeny or evolutionary descendents
...
In horse evolution while the earliest
ancestor Eohippus became extinct its desecendent survived to produce the
modern ‘Equus’
...
Thus the extinction of dinosaurs as a group is a case of true
extinction
...

The process of extinction is not always predetermined
...
Through
the use of computer models evolutionists can now examine the probalility of
extinction for large as well as small groups of organims
...


Pattern of extiniction :Fossil record reveals a few patterns for extinction
...
Larger organisms easily became extinct
...
He
explained this using ‘Mac Arthor’s law’
...


Causes of extinction :Even though extinctions are regular events in the history of earth they
are caused due to specific reasons (1) A mass extinction may be due to drastic changes in the environmental conditions
...
Thus
according to Red Queen’s hypothesis you have to keep running pretty fast,
just in order to stay in the same place
...
(ex
...
) (4) The spread of an epidemic
disease without any control can cause extinction
...
(6) A sudden cosmic radiation can
cause the death of large organisms
...

In the recorded history of earth, extinctions of major groups of
organisms were due to natural causes
...

Similar large scale extinctions have been observed by the end of Mesozoic era
and during Cenozoic time
...
Thus the cause for the modern extinctions is
invariably human acitivities
...

“The red-data book brought out regularly by W
...
F (World Wide Fund for
nature, Formerly IUCN - International union for the conservation of nature
and natural resources) provides a list of animals and plants that are endangered or have become extinct
...
4 Evidences for evolution
Various theories of evolution explain that the life originated on earth,
as simple organisms (like ameobae), from organic substances
...
Fossil records support the occurrence of
organic evolution to a large extent
...

(A) The evidences from comparative anatomy :
General similarities in structures are seen between groups of
organisms
...

The degree of relationship is measured by the degree of similarities they
possess
...
These comparisons also show the different plans of organisation in
various groups
...
The fore limb of a frog, a reptile, a bird and
several mammals like bat, man, horse, cow and whale have striking
similarities in structure with modifications to suit their mode of life
...
7
...
1

The fore limbs of these vertebrates are made up of similar bones
such as humerus, radius, ulna, metacarpels and phalanges
...
Thus, they help
frogs in hopping, the reptiles in crawling the birds and the bats in flying, the
whales in swimming, the horses in running and so on
...

Such structures with similar fundamental plan and different
functions are termed as homologous organs
...
The brain of man resembles that of other vertebrates
...

Organs like heart, eye, ear and kidney of various vertebrates, also
show homology
...


283

Vestiges:
Some organs which are well developed and functional in the
ancestral types have lost their functions in their descendants
...
Hence they are reduced
and remain as remnants
...

A change in the environment has made them useless in the present
environment conditions
...
These vestigial organs serve as evidences for the process
of evolution in organisms
...
7
...
2 Vestigial organs

284

Nearly 180 such vestigial organs can be cited in man
...
,

Human vestigeal organs
a
...
Herbivorous
food constituents like cellulose requires a long duration of time for digestion
...
The process of digestion is
carried out with the help of the intestinal bacteria that are lodged in the
caecum of these herbivores
...
There by, it gradually became smaller and appears as a vestige,
in man
...
Coccyx
The tail which is so useful and characteristic of lower vertebrates has lost its
function in human
...
The coccyx vertebrae are
originally meant for attachment tail muscles
...

c
...

This molar tooth is functional in primates
...
In some it may not erupt at all
...
In
their adults, they are represented only near the mouth and the eyes
(B) Evidences from embryology
Embryological studies are of considerable importance as they give
ample proof for the theory of organic evolution
...
The
study of the evolutionary history of species or race is called as phylogeny
...
In all the
vertebrates we are able to notice that cleavage starts only after fertilization
...
The blastula is
converted into a gastrula by the process called the gastrulation
...
In further development the embryos of different vertebrates greatly resemble each other
...
In the earlier
days of the development, it is difficult to distinguish a human embryo from
that of a bird or an amphibian
...
A fish embryo very much
resembles an amphibian embryo than a mammalian embryo
...

a)
...
The embryonic kidney of all vertebrates consists of pronephric
tubules
...
The mesoanephros
appear and form the adult functional kidney in the fishes and amphibians
...
This similarity in origin of the kidneys, in the various vertebrate groups
has led to infer that these three sets of tubules probably represent the single
kidney of the common vertebrate ancestor
...
The development of heart:
In all the vertebrates, the heart begins as a pair of tubular structures,
the endocardial tubes which later fuse to form the primitive tubular heart
...
Later, by the
development of a partition it becomes two chambered as in the case of the
286

adult fishes
...
The three chambered heart later gives rise to the incipient
four chambered heart as in adult reptiles
...
Finally at the level of the birds and
mammals the heart becomes completely four chambered
...
This type of development indicates a common ancestry for all
the vertebrates
...
The development of tooth:
In the same way the appearance of tooth buds in the embryos of
birds indicates their descent from the ancestors (reptile like forms) which
had teeth
...
He propounded the famous law known as
the ‘Biogentic law’ or the theory of Recapitulation
...
In other word ontogeny repeats phylogeny, which mans
the ancestral characters reappear in the developmental stages of an
individual
...

Though Hackel’s theory is accepted by many scientists a few raised
objections against his law (1)
...

For example in animal phylogeny the teeth evolved before the tongue but in
the mammalian ontogeny the tongue appears earlier than the teeth
(2)
...
An young mammal never looks like an adult fish or reptile
...
(3) The developmental
history is too much precised when compared with the evolutionary history
...
An amphibian has not evolved from an adult
287

fish by proceeding beyond that stage
...
Similarly the human embryo recapitulates the embryonic history
and not the adult history
...
7
...
3 Comparison of embryos of vertebrates

(C) Evidences from physiology:
The studies on physiology and biochemistry prove that the process
of evolution has occurred biochemically
...

a) Similarity of biomollecules
The nucleic acid which forms the basic hereditory material for all
the diversified groups strongly support the common ancestry
...
For example, trypsin, the proteolytic enzyme is
found through out the animal kingdom
...

The hormones of different vertebrates are also wide spread in
animals
...
This could
observed among the vertebrates too
...
When the thyroid glands of a tadpole are
removed it remains as a tadpole and never metamorphos into an adult frog
...
Like wise the hormones from the thyroid gand of
a cattle can be effectively used in the treatment of thyroid deficiencies
...
But
the haemoglobin crystals belonging to animals of the same genus are more or
less identical
...

The virus that causes polio in human can cause the same disease in
monkeys and apes but not in other vertebrates
...

A disease called gout occurs in both because of the accumulation of uric
acid in the blood vessels of the joints
...
The serological tests:
The serological tests are conducted in closely related organisms
...
For instance, the blood of a dog
was injected into a rabbit
...
Sufficient time was given for the antibodies in the rabbit to attain a
289

high level of concentration
...
When it was mixed with the serum of the dog, the
antigen-antibody reactions took place
...
This
reaction will not happen if the rabbit is not immunized
...
7
...
4 Serological tests

If the antidog serum is mixed with the serum of the wolf, precipitation
occurs but not to that extent as in the case of the dog When the same, test is
conducted with the fox and the cat (all coming under the order carnivora) the
same degree of relationship could be shown with the degree of precipitation
...

Such biochemical tests apart from providing a sound evidence for
evolution they solve many taxonomical problems too
...
Biogeography is the spatial
distribution of organisms upon the earth’s surface at various periods
...
In course of time they may be modified so as to call them as
different species
...
The Arabian one humped
camel living in the vast deserts is highly adapted for the desert life by storing
water in the (pouches of the) stomach, food in the hump and having broad
heavily padded feet to hold grip in the loose sand
...
Its feet are not padded but quite hard enabling the
animal to move about more freely on the rocky terrains of central Asia
...

Charles Darwin during the course of his voyage in the ship ‘HMs
Beagle’ observed the flora and fauna of Galapagos islands which is 600
miles away from the west coast of south America, The inhabitants of each
island differed from those of other islands as well those of the main land
...
We may
suggest that these are the migrants from the main land or from other
landmasses
...
7
...
5 Darwin’s finches

The famous Darwin’s finches (13 species of finches) inhabiting
different islands exhibit special adaptations for their particular modes of life
...
On the other hand
plant eaters had short strong beaks, which were useful in breaking open hard
nuts
...
Those living
among green, had green feathers, which blended well with the background
...
And
hence they had a wider range of adaptive radiation
...
Oparin’s theory is called as
(a) the Biogenesis theory

(b) the Primary abiogenesis

(c) Cosmozoic theory

(d) Special creation theory

2
...
The proposal that living forms are animated forms of non-living matter was
provided by
a) Empedocles

b) Thales

c) Lamarck

d) Aristotle

4
...
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

6
...


7
...
An earliest Jawless fish was
(a) Sword fish
(c) Mullet

(b) Cat fish
`

(d) Jamoytius

9
...
The coal and petroleum are obtained from the forests of
a) Devonian period

b) Mesozoic era

c) Cretaceous

d) Tertiary period

11
...
Archaeopteryx was a connecting link in between
(a) Amphibians and reptiles

(b) Fishes and amphibians

(c) Birds and reptiles

(d) Birds and mammals

13
...
Identify the early ancestor of horses
a) Dinosaurs

b) Seymouria

c) Archaeopteryx

d) Hyracotherium

15
...
What was the nature of the primordial earth according to J
...
S Haldane ?
2
...

3
...

4
...

5
...
What is ‘ice age’ ?
7
...

8
...
What is the significance of Seymouria ?
10
...

11
...

12
...
Write any two causes for extinction of animals
...
What is precambrian period ?
15
...
What is vestige
...
What is abiogenesis ?
2
...

3
...

4
...
B
...
Haldane’s hypothesis
...
Give an account on Coacervation theory
...
Explain the six epochs of Cenozoic era
...
What is the evolutionary significance of fossils?
8
...

9
...

10
...
Tabulate the geological time scale
...
Give an account of the Mesozoic era
...
What is mass extinction ? Provide the causes for such extinctions
...
Write an essay on fossils and methods of fossilization
...
Give an account on Extinct animals
...
How do the serological tests help in relating the animals?
7
...


294

Reference books
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...
I
...
I
...
Ekambaranatha
Ayyar and T
...
Ananthakrishnan, Reprint 2003
...
Manual of Zoology Vol
...
Part
...
(Invertebrata), M
...
N
...

3
...
II
...
Ekambaranatha Ayyar and
T
...
Ananthakrishnan, Reprint 2003
...
Viswanathan
(Printers andPublishers) Pvt
...
38, Mcnichols Rd,
Chetput, Chennai - 600031
...
Chordate Zoology E
...
Jordan and P
...
Verma
...

S
...
and Company Ltd, Ram nagar,
New Delhi - 110 055
...
A Text book of Zoology R
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Vidyarthi and P
...
Pandey S
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6
...
S
...
K
...
S
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7
...
Arumugam Reprint
...
Saras Publication
A R P Camp Rd, Peria vilai, Kottar,
Nagercoil - 629 002
...
Genetics P
...
Verma and V
...
Agarwal Reprint 2003
...
Chand and
Company Ltd, Ram nagar, New Delhi - 110 055
...
A Text book of Human Anatomy T
...
Ranganathan 6/e Rev
...

S
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10
...
S
...
K
...

S
...

11
...
Arumugam Reprint
...
Saras
Publication A R P Camp Rd, Peria vilai, Kottar,
Nagercoil - 629 002
...
Economic Zoology G
...
Shukla and Upadhyay 4/e 1998
...

13
...
Reprint 2003
...
Chand and Company Ltd,
Ramnagar, New Delhi - 110 055
...
Concept of Evolution P
...
Verma and V
...
Agarwal Reprint 1999
...
Chand and Company Ltd, Ram nagar,
New Delhi - 110 055
...
Organic Evolution N
...
1999
...


Visit websites
http://home
...
net/~dlblanc/taxonomy
...
utm
...
htm
http://can-do
...
html
http://www
...
loretto
...
htm
http://cellbio
...
edu/cellbio/cancer biology
http://dir
...
com/Health/Medicine/Oncology
http://www
...
com/107/
http://www
...
com/biosci/ap/seeleyap/
296



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