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Structural Organisation In Animals And Plants

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Structural Organisation in Animal and Plants PDF Notes, Important Questions and Formulas


  1. The word Pheretima was at first used by Kinberg is 1867.
  2. At first Indian earthworm was completely described by prof. Karm Narayan Bhal.
  3.  Complete details of Indian earthworm was published in "The Indian zoological memoirs on Indian Animal type".






Metamerically segmented & usually elongated worm like.





Segementation distinct. No parapodia Head not district


Mainly terrestrial earthworm





Female genital pore single while male one pair. Citellar 14,15 & 16







Other species of earthworm are as follows -

  1. Megascolex - Found in South India.
  2. Dravida - Found in South India.
  3. Eutyphaeus - Found in North India.
  4. Lumbricus - Found in Europe. Most common species of earthworm.

Habits and Habitat

  1.  Earthworms are compolitan in distribution.
  2.  They are found in moist soil.
  3.  According to Darwin one acre of land may contain 50,000 earthworms.
  4.  They are found 2 to 10 feet deep in the soil, so they are called Earthworm.
  5.  They are nocturnal.
  6.   Their breeding season is from July to October.


  1. It has a long, cylindrical, narrow, bilaterally symmetrical body, well adapted for burrowing. Length of the body is 15 to 20 cm and diameter is 3 to 5 mm.
  2. The worm is brown or clay coloured due to the presence of porphyrin.
  3.  Dorsal surface is darker then ventral and carries a dark mid dorsal line due to dorsal blood vessels.
  4.  Body is metamerically segmented.
  5.  The number of segments are 100 to 120 are called metameres or somites.
  6.  Earthworm has no district head and no conspicuous sense organ head appendages also lacks.
  7.  First segment of the body is called peristomium or buccal segment which bears mouth.

  8.  Fleshy lobefold overhanging the mouth is called prostomium.
  9.  Last segment called pygidium. The last segment of body is also known as anal segment as it carries terminal anus.
  10.  14th, 15th. And 16th segment modify to form band like glandular structure called c1 itellum. Citellum secretes mucous, albumin and from egg case or cocoon for eggs.
  11.  It divides the body into 3 Parts
  1. Pre-citellar region-includes 1 to 30 segments.
  2. Citellum region – includes 14 to 16 segments.
  3. Post clitellar region- Includes 17 to last segments


  1. In the middle of each segment a ring of tiny ciliated bristles called setae are present. They are made up of chitin.
  2. A setae measures 0.26 mm in length to 0.03 mm in width
  3. A setae is fiant yellow coloured S-shaped with a swollen middle part.
  4. It’s one third part projects above the surface of skin termed as neck, the embedded two third part is termed as base.
  5. Setae is locomotory structure. 

  6. The arrangement of setae in a ring in each segment is known as perichaetine arrangement.
  7. Each segments possess 80 to 120 Setae.
  8. There are no setae in the first and last segments and in the clitellum of a mature worm.

External Apertures Mouth

  1. It is terminal aperture located in the first segment peristomium.
  2. Dorsally mouth is covered by prostomium like a hood.

It is a small vertical slit present in the last segment.

Dorsal pores
Dorsal pores are present in the intersegmental groove starting from 12/13 upto last but one segment. Coelomic fluid comes out of these pores to moisten the skin


  1.  Except first 6 segment each of the body carries 200- 250 nephridipores, which open out as minute opening.
  2.  Cilitellar segment carries 2000 nephridiopores.

Spermathecal pores
Spermathecal pore are present in the intersegmental groove of 5/6, 6/7, 7/8 and 8/9 (4 pairs).

Female genital pore
Located on the mid ventral side of 14th segment.

Male genital pores
A pair of male genital apertures is located on the ventral side of the 18th segment.

Genital papillae

  1. They are also called copulatory papillae.
  2.  One pair of these papillae opens through apertures on latero-ventral sides on 17th    segment and the other pair on 19th  segment



    Phylum - Chordata
    Dorsal, Hollow, Tubular Nerve Cord, Notochord, Pharyngeal gill slits
    Group - Craniata
    Notochord replaced by vertebral column Mouth bears jaws.
    Super class - Tetrapoda
    Bears four limbs
    Class - Amphibia
    Dual life on land & in water.
    Order - Anura (Salientia)
    Tail absent
    Species - tigrina (Indian bull frog)


  1.  Body is divided into head & trunk only. Neck and tail region is absent.
  2.  Head bears mouth, eyes, eyelid & nictitating membrane, external nostrils and a pair of tympanic membranes.
  3.  Trunk bears two pairs of limbs, viz., a pair of fore limbs and a pair of hind limbs.
  4.  Frog sites in a squatting posture.
  5.  Frog is poikilothermic (Cold blooded) animal.
  6.  Male frog has vocal sacs and amplexy pads or nuptial pads on each first finger.
  7.  Crocking sound produced during rains is a mating call.
  8.  Rana tigrina is the name signifies mottled colouration of body like that of a tiger. Its common name 'Indian Bull Frog' is due to presence of a hump on the back.

Differences between frogs and toads














Outer surface

Skin is soft. Moist and gelatinous.

Skin is dry and without scales



Cutaneous artery is present

Cutaneous artery is absent


Vocal sac

Male frog has vocal sacs.

Vocal sac are absent







Upper jaw bear teeth

Teeth are absent


Paratoid gland





Tongue bifurcated at the tip

Tongue is not bifurcated


  1. Skin is moist, gelatinous, and smooth and scale less, respiratory.
  2. Dorsal side of the skin of frog is grey or green with drak sports. Ventral part is whitish yellow.
  3. Epidermis is made up of stratified epithelium.
  4. Dermis is divisible into stratum spongiosum and stratum compactum. In the stratum spongiosum serous glands, mucus glands and chromatophore cells are present.
  5. During hibernation (winter sleep) or aestivation (Summer sleep) the metabolic rate is minimum and the skin acts as the sole respiratory organ (cutaneous respiration).
  6. Frogs can change their skin colour to blend with surroundings. This is called camouflage.
  7. Body division: The body has two main divisions head and trunk; absence of neck and tail helps both in jumping on land and swimming in water.
  1.  Head : Head is anteior flattened triangular part with, a wide transverse terminal mouth, a pair of small dorsal external nares, two dorso-lateral eyes, a mid-dorsal dorsal light coloured brown spot or third eye or pineal body and obliquely placed pigmented circular tympanum or ear drum. Eyes are provided with nictiating membrane for protection.
  2. Trunk: Trunk is the large, oval, flattened main part of the body. It is differentiated into hard anterior thorax and soft posterior abdomen. The trunk is provided with a pair of fore and hind limbs. The hind limbs are much larger and muscular than the fore limbs, end in five digits.



  1. The alimentary canal and its associated digestive glands constitute the digestive system. Alimentary canal is a long tube, starts with mouth and ends in cloaca.
  2.  The upper jaw bears two types of teeth, maxillary teeth (present on the margin of upper jaw) and vomerine teeth (present in two groups).
  3. Forked tongue (bilobed) is attached to the tip of lower jaw. Tongue is attached in front and free behind. It is helpful in catching the prey.
  4. Buccal cavity opens into a muscular bag like structure called stomach through short pharynx and oesophagus.
  5.  Salivary glands are absent.
  6. Intestine is not divided into small and large intestine.
  7. Intestine opens into a thin walled bag like structure, called rectum, which opens into cloaca through anus.



    The wide range in the structure of higher plants will never fail to fascinate us. Even though the angiosperms show such a large diversity in external structure or morphology, they are all characterised by presence of roots, stems, leaves, flowers and fruits.
  2. ROOT
    Radicle comes out/arise from the seed coat in the form of soft structure and move toward the soil. It develops and forms primary root.

Roots are of two types:

  1. Tap root
  2. Adventitious root
  • Tap root: – It develops from radicle which is made up of one main branch and other sub-branches. eg. : Dicots
  • Adventitious roots: – In some plants after sometime the growth of tap root which arises from radicle stops and then roots develop from other part of plant which are branched or unbranched, fibrous or storage, are known as adventitious roots. eg. : Monocots
  • Fibrous roots:-In monocot plants, the primary root is short lived and is replaced by a large number of roots. These roots originate from the base of the stem and constitute the fibrous root system. Eg.:-wheat plant


Tap and adventitious roots are modified in different forms to perform special functions are called as modified roots.

           1.    Modified tap root for storage :

  1. Fusiform roots/Spindle root - These root are thicker in the middle and tapering on both ends. In this type of roots root help in storage of food. a.   Eg. :- Radish
  2.  Conical roots - These roots are thicker at their upper side and tapering at basal end eg. Carrot
  3.  Napiform - These roots become swollen and spherical at upper end and tapering like a thread at their lower end. Eg. Turnip (Brassica rapa), Sugarbeet (Beta vulgaris)
  4. Shape and get swollen & fleshy at any portion of roots Eg. Mirabills
  5. Nodulated root - Nodules are formed on branches of roots by nitrogen fixing bacteria. (Rhizobium).  Eg. Plants of leguminosae family (Papilionatae) – Pea

 2.  Tap root modified for respiration
The plants which grow in marshy areas, scarcity of oxygen is found.

The plants, which grow in this region some branches of tap root grow vertically upward and comes on surface of soil. These roots are called pneumatophores have minute pores called pneumathodes or lenticels by which air entered the plant and get oxygen for respiration.

Eg. Rhizophora, Mangrove, Heritiera
Modification of adventitious roots:

  1. Tuberous adventitious root: When food is stored in these roots, they become swollen and form a bunch. E.g. Sweet potato (Ipomoea batatus)
  2. Fasciculated roots - These are adventitious roots occuring in clusters and all of them are swollen. (These roots have no definite shape) Eg. Asparagus, Dahlia
  3. Fibrous - Roots are very thin and filamentous. Eg. Grass, Wheat

Taxonomic status:-

  • Phylum - Arthropoda (Jointed appendages and chitinous exoskeleton)
  • Class - Insecta (3 pairs of jointed legs)
  • Order - Dictyoptera/Orthropetra (Dissimilar wings)
  • Genus - Periplaneta
  • Species – Americana


  1. Introduction Fig. 1.39
  • It is also known as "American or common cockroach or ship cockroach”.
  • Size is about 34-53 mm long with wings that extends beyond the abdomen of males.
  • Cockroach of genus - Blatta has small wings in males but vestigeal in females.
  • It is omnivorous, nocturnal and cursorial (fast runner) animal.
  • Cockroach can run 130 cm/sec at 25°C.
  • Number of chromosomes = 34
  • It also exhibit cannabalism, feeds on their fellows ocassionaily.

 2.  Morphology:-Body is divided into three parts Body=Head + Thorax + Abdomen

        =6+3+11=10 segments in embryo.

        =1+3+10=14 segments in adults.

  • The entire body is covered by a hard chitinous exoskeleton (Brown in colour).
  • Exoskeleton of chitin plates occurred in each segment.
    Chitin plate called "sclerites".
  • Sclerites joined each other by "membrane" called "articular or arthroidal membrane."

Sclerites of dorsal side - tergum or tergite
Sclerites of ventral side - Sternum or sternite
Sclerites of lateral side - pleurons or pleurites.

i.  HEAD

  • It is triangular and "Hypognathus", bent downwards at an angle of 90° from the long axis of body.
  • Sclerites of the head joined fully and form head capsule.
  • Top part of Head is called "Vertex" and on the vertex a chitin plate present called "Occiput".

On the lateral side of head apex 1 pair of compound eye


  • each compound eye made up of 2000 units called "ommatidia"
  • A small light coloured spot called fenestra or ocellar spot is located upon dorsal surface close to each eye. In insect it function as a photoreceptor organ.

In Cockroach - Inactive and called "Vestigial simple eye".
Antennae: - Lateral side of head apex, 1 pair of antennae are present, acts as, main receptor of touch, temperature and vibration in cockroach.

  • All these sensory receptors present on antenna help in monitoring the environment. Each antenna extending forwards from an antennal socket located dorsally upon head capsule near the compound eye of its side. These are long, filamentous, unbranched and free moving.
  • A big chitin plate situated below the vertex called frons or forehead.
  • two long flattened chitin plates situated on lateral side called "gena" or "cheek"
    A big chitin plate present in anterior part of frons called "Clypeus". a movable chitin plate joined with anterior part of clypeus known as "Iabrum" or "Upper lip".
  • A mouth situated in the anterior side of head which is surrounded by many chitinous structure called "mouth parts"

Mouth Parts of Cockroach”:- "Bitting and chewing type" A cavity formed due to mouth parts called "Preoralcavity" or "cibarium".

  1. Labrum or upper lip:- Broad and flattened terminal sclerite of the dorsal side of head capsule moving articulated to the clypeus. It dorsally overhangs the mouth and hence referred to as "upper lip".
  2. Mandibles:- Jaw
    pair of triangular structure with Chitinous teeth on inner surface.
    They form the lateral wall of preoral cavity and moves horizontally (Grinding)
  3. First maxillae: -
    One-pair and form lateral wall of preoral cavity.
    With the help of maxillary palp cockroach pickup its food and put it in preoral cavity for chewing.
    Maxillary palps also used as brush to clean antenna and wing.
  4. Labium or lower lip" (Fused 2nd maxillae)
    Form floor of preoral cavity (Ventral side) and provides a platform for food materials.
  5.  Hypopharynx:- or”lingua”
    Small, non-chitinous flexible structure that lies on the floor of platform for food materials.
    It bears several sensory setae at its free end, and the common salivary duct opens at the base of hypopharynx, therefore it is also considered as tongue of cockroach.



Tissue: A group of cells in which cells are similar in structure, function and origin is called tissue. Group of similar cells along with intercellular substance perform a specific function such organisation is called tissue. But in a tissue, cells may be dissimilar in structure and function but they are always similar in origin.
Organ: Tissues are organised in specific proportion and pattern to form organ.
Organ system: When two or more organ perform common function by their physical &/or chemical interaction, they together form organ system.
Division of labour: Cell, tissue, organs and organ systems splits up the work in a way that they exhibit division of labour.

On the basis of functions & structure tissues are of four types:

  1. Epithelium/Epithelial Tissue: Covering & protective tissue.
  2. Connective Tissue - To connect structures, provide support to the body and transport substances in the body.
  3. Muscular Tissue - Helps in contraction & locomotion.
  4. Nervous tissue - To generate and conduct nerve impulses in body.


≫     Word Epitjelium was given by-Ruysch

≫     Word animal tissue was coined by- Bichat (Plant tissue by- Grew).

≫     Study of tissue-Histology.

≫     Histology word was given by-Mayer

≫     Father of Histology-Bichat

≫     Details study of tissue is called Microscopic anatomy.

≫     Founder of microscopic anatomy-Marcello Malpighi

A.     Epithelium Tissue

I.         Characteristics of epithelial tissue

  1. During embryonic development epithelium orginates first.
  2. Power of regeneration is present in this tissue while power of regeneration is absent or least power is found in nervous tissue.
  3. This tissue faces either a body fluid or outside environment and thus provide a covering or a lining.
  4. Word epithelium is composed of two words. A tissue which grows upon another tissue is called Epithelium.
  5. It always rest upon underlaying connective tissue. Epithelium is the only tissue in which cells are always arranged in uniform layer. Epithelium cells are compactly packed with little intercellular matrix.
  6. Due to absence of intercellular spaces blood vessels, lymph vessels & capillaries are unable to pierce this tissue so blood circulation is absent in epithelium. Hence cells depend for their nutrients on underlying connective tissue.
  7.  Basement membrane : Between epithelium and connective tissue, a thin non living acellular basement membrane is present which is highly permeable. Basement membrane consist of 2 layers.
  1. Basal lamina: Towards epithelium and it is made up of glycoprotein, which is secreted by epithelium cells.
  2. Fibrous lamina: Towards connective tissue, in which collagen and reticular fibres are suspended in mucopolysaccharide which is matrix of connective tissue. Mucopolysaccharide is present in the form of Hyaluronic acid.


So basement membrane is secreted by both epithelium and connective tissue.

 II.   Cell Junction: TO provide both structural and functional link between its individual cell epithelial cells modify to form following structures

(Intercellular Junctions): -

  1. Interdigitation –Finger like processes of plasma membrane which enter into cytoplasm of adjacent cell. These structure are mainly found in transitional epithelium.
  2. Adhering/Desmosomes-This type of (Macula Adherens) junction consists of stop intermediate fibre known as tonofibrils composed of keratin like protein. These filaments are deeply situated in the cytoplasm of respective cell. These structures provide mechanical support to stratified epithelium or performing cementing of respective cell. These structure provide mechanical support to stratidied epithelium or performing cementing to keep neighbouring cell together. E.g. Stratified epithelium
  3. Tight Junction- At some places plasma membrane of adjacent cells become fused to from tight Junction to stop substance from leaking across a tissue. These structures are mostly found in columnar epithelium.
  4. Gap Junction-Facillate the cells to communicate with each other by connecting cytoplasm to adjoining cells for rapid transfer of ions, small molecules and sometimes big molecules.

III.  Modification of plasma membrane of epithelium tissue:

i.   Microvilli

  1. These are minute process which are non motile, non contractile. They increase surface area by more than 20 times
  2. They help in absorption, secretion and excretion.
    They are present in the wall of Intestine, Gall bladder, Proximal convoluted tubule etc.



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