ANIMAL DIVERSITY
KINGDOM PROTISTA
General Characters

Q.What is the mode of excretion in protozoa?

i).Physical process involved-osmoregulation and active ion transport at the cell membrane

ii).Contractile vacuole and general body surface act as major excretory mode.

iii).Contractile vacuoles are basically two types as follows-

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Structure Trichomonas sp showing axostyle.

Q.What is axostyle?

This is one of the major component of cytoskeleton which maintain flexibility of body wall. Axostyle radiate from the flagellar basal bodies to the opposite extremity of the cells as axial skeleton. Found in all flagellates and spore forming Protozans.

Q.What are exconjugants?

Sexual reproduction in ciliates is a direct exchange of genes without first packaging them in either egg or sperm cells. To accomplish this, two sexually compatible ciliates fuse along a shared surface, the membrane between them disappears and a mutual exchange of genes occurs. This process is known as conjugation and the fused ciliates are called conjugants. Shortly after nuclear fusion the two ciliates separate and each is then called an exconjugant. Each exconjugant undergoes mitotic nuclear divisions to restore the species specific number of cell nuclei.

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Classification of Protozoa up to classes

Q.State the systematic position of the followings (mentioning two diagnostic feature of each taxon)

a)Euglena, b)Paramecium .

a)Subkingdom:Protozoa

Phylum: Sarcomastigophora (According to Levine et al,1980)

Salient feature of phylum Sarcomastigophora- (for Protozoan character follow general characteristics section)

i)Nucleus-single type

ii)Locomotory organelle-by either pseudopodia or flagella or both.

iii)Mode of reproduction-asexual but in case of sexual mode of reproduction they follow syngamy.

b)Subkingdom:Protozoa

Phylum:Ciliophora (According to Levine et al, 1980)

Salient feature of phylum Ciliophora-

i)Nucelues-two types (macro and micro)

ii)Cilia- simple or compound cillary organelles are present in at least one stage of life cycle. Subpellicular cilia present even when surface cilia is absent.

iii)Excretion-through typical contractile vacuole.

Locomotory organelles and locomotion—
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In Amoeba

Q.What is solation-contraction theory in amoeboid movement? (b)Discuss the role of microfibrils in amoeboid movement.

In Amoeba, movement of the animal is made by the throwing of pseudopodium, called amoeboid movement. In the direction of movement of Amoeba a new pseudopodium is formed and the pseudopodium at the opposite side gradually disappears.

(b) For the explanation of the change between cytosol and cytogel, the cytoskeleton is involved. The cytoskeleton is constructed with microfibrils. The construction element of the microfibril is called tubulin. When tubulins are assembled to form a scarfold, the cytoplasm becomes much viscous and called the cytogel. When tubulins are disassembled, the cytoplasm become less viscous and called the cytosol.

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In Paramecium
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PHYLUM PORIFERA
General Characters

Q.What is spongiome?

The contractile vacuole has several structures attached to it in most cells, such as membrane folds, tubules, water tracts and small vesicles. These structures have been termed the spongiome; the contractile vacuole together with the spongiome is sometimes called the "contractile vacuole complex (CVC). The spongiome serves several functions in water transport into the contractile vacuole and in localization and docking of the contractile vacuole within the cell.

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Q.What is mesohyl?

The connecteive tissue between the pinacoderm and choanoderm is called is called mesohyl. It is composed of a proteinaceous, gel-like matrix that contains differentiated and undifferentiated cells-amoeboid cells. Important cells of mesohyl are archeocytes, lophocytes, sclerocytes, myocytes.

 

Q.Give example of few larval forms of Porifera.

Coeloblastula larva, amphiblastula larva, parenchymella larva etc.

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Classification up to Classes

Q.Give salient featute of class calcarea.

i)Habitat-marine shallow coast water, with a height less than 10cm,

ii)Spicule-all are same general size and composed of calcium carbonate (either calcite/aragonite),Mono axon or 3-4 pronged.

iii)Pattern of canal system-all 3 grades of structure (asconoid, syconoid and leuconoid) are encountered.

 

Q.State the systematic position of Spongilla sp .

Phylum:Porifera

Class:Demospongiae

(According to Ruppert-Barnes, 6th ed,1994)

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Canal System in Sycon

Q.What do you mean by canal system? Give example.

The numerous inhalant apertures (ostia) perforating the body into a system of canals permeating almost whole body open to the exterior by one or more large exhalent opening oscula in Porifera. The openings and canals through which a continuous flow of water is maintained by choanocytes called the canal system.

This type specialized form of adaptation is evident in phylum Porifera.

Q.Add a note on the main advanvement of leuconoid canal system over that of syconoid type.

i)Thickened, incomplete distribution of podocytes in mesenchyme are found in syconoid type of canal system. Where as in leuconoid type mesenchyme is highly elaborated and traversed by incurrent canals or subdermal spaces.

ii)In syconoid type choanocytes distribution is limited to radial canals. This distribution becomes limited to tha flagellated chambers and the flagellated chambers open by narrow apopyles.

iii)Spacious spongocoel of syconoid type usually obliterated in leuconoid type.

These advanced features in leuconoid type of canal system help to increase the most efficiency rather than other canal system.

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Syconoid canal system

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Leuconoid canal system

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PHYLUM CNIDARIA
General Characters

Q.What is polyp?

Polyps are chefly attached, sessile, benthic animals with a mouth-up orientation. Resembles a flower and its stalk.The stalk is cylindrical elongate column arising from an aboral pedal disc.At the opposite end of the column, the manubrium (or hypostome), an elevation with the mouth at its summit- is situated in the centre of an oral disk.The pedal disk and column of the polyp, but not the oral end, may secrete a chitinous exoskeleton, the periderm, which provides for protection and attachment to the substratum.

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Q.What is medusa?

A medusa has the shape of an umbrella or a bell.The oral surface is called the subumbrella and the opposite aboral side is the exumbrella.The mouth is at the tip of a mobile appendage, the manubrium, that resembles an elephant trunk.Tentacles arise from the margin of the bell and around the mouth.

Medusae are commonly known as jellyfish because their connective tissue (mesoglea)is thick, gelatinous and buoyant;polyp mesoglea is thin, often composed of little more than the combined epidermal and gastrodermal basal laminas.

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A Hydra in longitudinal section showing coelenteron.

Q.What is coelenteron?

This is a blind, sac like cavity lined by gastrodermis and opening to the exterior via the mouth.Among madusae, it is often regionally specialized into a central stomach from which radial canals extend to join a marginal ring canal.The coelenteron is a multifunctional compartment with roles in extracellular digestion, circulation, excretion, reproduction and hydrostatic skeletal support.

The coelenterons is the internal transport system of cnidarians.

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Classification up to Classes

Q.Give salient features of class Anthozoa.

(Includes exclusively marine sea anemone, corals, sea pens etc; largest Cnidarian taxon)

i)Form-Polyp is responsible for both sexual and when present for asexual reproduction (medusa is absent)

ii)Mesoglea-contains amebocytes and is thus a true connective tissue. Anthozoans are the only Cnidarian taxon that has all 3 types of cnidae(nematocyst, sporocyst and ptychocyst).

iii)Mesoglea-cellular.

iv)Stomodaeum-strongly developed.

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Q.Give salient feature of class Hydrozoa.

(They are the only Cnidarians to form colonies combining both polyp zooids and medusa zooids; Hydra sp, Obelia sp)

i)Nematocyst-restricted to epidermal structures.

ii)Mesoglea acellular.

iii)Coelenteron- is undivided and without stomodaeum.

iv)Gonads are usually ectodermal in origin.

Metagenesis in Obelia
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PHYLUM PLATYHELMINTHES
General Characters

Q.What is flame cell?

A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms (except the turbellarian order Acoela), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.

The flame cell has a nucleated cell body, with a "cup-shaped" projection, with flagella covering the inner surface of the cup. The beating of these flagella resemble a flame, giving the cell its name. The cup is attached to a tube cell, whose inner surface is also coated in cilia, which help to move liquid through the tube cell. The tube opens externally through a nephropore, or, in the trematoda, into an excretory bladder. The function of these cells is to regulate the osmotic pressure of the worm, and maintain its ionic balance. Microvilli in the tube cell may be used to reabsorb some ions.

 

Q.Give three salient features of Platyhelminthes.

i)They are triploblastic acoelomate, having organ system that occur in the middle layer.

ii)Digestive system-with single opening that leads to a well developed gastrovascular cavity. Anus absent.

iii)Nervous system

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Flame cell in Fasciola

Classification up to Classes

Q.Give the scheme of classification of Platyhelminthes.

According to Ruppert and Barnes, 1994, 6th ed)

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Q.Write generic example of a free living and a parasitic flatworm

Platyhelminthes include the free-living (Turbellaria) and the parasitic fluke (Trematoda) and tapeworm (Cestoda).

Free-living forms— Paramalostomum coronum; Kytorhynchella meixneri.

Parasitic flatworms— Taenia Saginata; Echinococcus granulosus.

Life history of Taenia Solium
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PHYLUM NEMATHELMINTHES
General Characters
Classification up to Classes
Life history of Ascaris lumbricoides and its adaptation
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PHYLUM ANNELIDA
General Characters

Q.What is botryoidal tissue?

A peculiar type of mesenchyme or packing tissue found in the bodies of leeches; consisting of a network of darkly pigmentded tubular cells having intracellular ducts filled with red blood-like fluid. The botryoidal tissue is composed of two different cell types--granular botryoidal cells and flattened endothelial-like cells--localized in the loose connective tissue between the gut and the body wall sac. In response to a surgical wound, botryoidal tissue cells changed their shape and formed new capillary vessels. Concurrently, botryoidal cells secreted iron from cytoplasmic granules into the new cavity: this secretory activity appeared to be related to intracellular calcium fluctuations. At the end of the angiogenic process, botryoidal cells lost their contact with the basal lamina and moved freely in the circulating fluid towards the lesioned area. Interestingly, circulating botryoidal cells were found to carry melanin in the wounded area. This function is probably involved in defense processes (Eguileor et al., 2001).

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T.S. through crop with diverticula

Classification up to Classes
Nephridia

Q.What is nephridia?

A Nephridium is tubular coiled structure. It starts from a rounded funnel shaped structure called nephrostome. The nephrostome opens in a coiled tube called nephridial tubule which is lined with cilia.

The nephridial tubule opens outside the body through a small opening called nephridiopore.

The body fluid of earthworm rich in nitrogenous wastes enters the nephridium through nephrostome and passes into nephridial tubule. In the nephridial tubule the useful substances present in fluid are absorbed. The remaining fluid containing high percentage of nitrogenous wastes is excreted out of the body through nephridiopore with the help of movements of cilia.

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Showing different parts of a single nephridium

Showing position of nephridia

Metamerism

Q.Define metamerism. Give example.

Q. Name the phyla other than Annelida where metamerism is found.

Metamerism is the phenomenon of having a linear series of body segments along an anterior-posterior axis, fundamentally similar in structure, though not all such structures are entirely alike in any single life. Some of them perform special functions.

Metamerism appears in a variety of metazoan phyla, including some Coelenterates, Platyhelminthes, Annelids, Arthropods and Chordates.

 

Q. Discuss the different theories on the origin of metamerism.

There are several conflicting views regarding the origin of metamerism. Such as— (a)Pseudometamerism theory (By Hyman, 1951), (b)Cyclomerism theory- (by Sedgwick,1884)/ Enterocoelous theory of coelom origin, (c)Corn or Fission theory (By Perrier, 1882), (d)Locomotion theory (By Clark, 1964).

a)Pseudometamerism theory (By Hyman, 1951):

i)According to this theory the metamerism evolved secondarily as a result of repetition of body parts whose ancestor was acoelomate and unsegmented and contained the various systems or organs.

ii)The metameric segmentation was linked with the evolution of coelom.

b)Cyclomerism theory- (by Sedgwick,1884)/ Enterocoelous theory of coelom origin:

i)According to this theory coelom is associated with the origin of metameric segmentation.

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Diagram illustrating the cyclomerism theory of metamerism

ii)The origin of coelom took place from the gastric pouches of some ancestral anthozoan coelenterates and they remain separated from the main gastric cavity and arranged in linear fashion.

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PHYLUM ARTHROPODA
General Characters

Q.Give three salient features of phylum Arthropoda.

i)Body-Segmented with bilateral symmetry.

ii)A pair of externally jointed appendages is usually present in each segment.

iii)Body cavity is haemocoel, true Coelom is vestigial in adults. And circulation is of open type.

 

Q.What do you mean by uniramous and biramous appendages?

a)UNIRAMOUS: The appendages of many arthropods (such as hexapods, myriapods and arachnids) have a single branch or ramus and are said to be uniramous.

b)BIRAMOUS: Crustaceans and trilobites have two major branches and thus called as biramous.A biramous appendage typically begins with a proximal protopod, which often is divided into two articles, a coxa and a basis.Forking from the basis are the two rami consisting of a lateral exopod and a medial endopod.

Classification up to Classes

Q. Give the systematic position of Limulus (mentioning features of their respective taxa).

Phylum: Arthropoda

Sub Phylum: Chelicerata

Class:Merostomata

Features of phylum—(Follow general characteristic part)

Features of sub phylum—

i)Body divided into an anterior cephalothorax or prosoma, which is wholly or partly covered by a dorsal carapace and a posterior abdomen or opisthosoma without legs.

ii)Appendages uniramous.

iii)They lack antennae.

Features of Class –

i)Aquatic with 5 or 6 pairs of abdominal appendages modified as gills.

ii)A prominent spike like caudal spine or telson is present at the end of the body.

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UNIRAMOUS

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BIRAMOUS

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Vision in insect

Q.What are the major types of photoreceptors of arthropods?

Photoreceptors or eyes are widespread and often well developed and sophisticated in arthropods. Two different types of eyes, median pigment-cup ocelli and lateral compound eyes, are found in arhthropods. Both contain rhabdomeric photoreceptor cells connected with protocerebrum by optic nerves, but they differ in their morphology and function.

 

Q.What is ommatidium?

Compound eyes are composed of many light receiving units known as ommatidia. Compound eyes usually are flush with the surface of the head and if so are said to be sessile. This is independent light-detecting unit of the compound eye. A compound eye may contain as few as 15 to as many as several thousand of these units.

iii)Shape- Elongate and rod-shaped. The exposed outer or distal, end of the ommatidium is the transparent cornea (or lens), which is part of the exoskeleton and focusing system. (For further information follow contact)

 

Sensory complex of ommatidium—

i)Consists of seven or eight light sensitive retinular cells, clustered to form a retinula.

ii)The retinular cells contain rhodopsin arrayed on the membrane of microvilli arising from their axial surfaces. The microvilli are pointed …….(For further information follow contact)

Q.Define rhabdome.

Rhabdome is the mass of microvilli belonging to the cells of the retinula. This axial concentration of microvilli results in a high density of rhodopsin and increase the likelihood that light entering the rhabdome will strike a pigment molecule. Retinular cells also contain proximal screening pigment.

Eye in Cockroach
Metamorphosis in Lepidoptera
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PHYLUM MOLLUSCA
General Characters

Q.What is the function of radulla? Mention its location?

The radula (plural radulae or radulas) is an anatomical structure that is used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus. The radula is unique to the molluscs, and is found in every class of mollusc except the bivalves, who use instead cilia, waving filaments that bring minute organisms to the mouth.

Q.What do you mean by chiastoneury?

Due to torsional rotation of the visceral mass the developing nervous sytem in the post-torsional larva the original right parietal ganglion comes to lie on the left, dorsal to the gut (supra-intestinal ganglia) and the left parietal lies on the right below the level of the gut (infra intestinal ganglion). A the parietal ganglia have reversed sides, the entire visceral loop is twisted in a figure of “8” (eight) this condition is known as streptoneury or chiastoneury.

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IN PILA, THE CHIASTONEURY IS DIFFUSED BECAUSE OF THE FUSION OF THE INFRAINTESTINAL GANGLION WITH RIGHT PLEURO-PEDAL GANGLIONIC MASS. THE ORIGINAL INFRAINTESTINAL NERVE STILL PERSISTS AS AN EVIDENCE OF MIGRATION AND FUSION OF INFRAINTESTINAL GANGLION

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Classification up to Classes

Q.Give salient features of class aplacophora.Give tow examples of the class.

i)Shell-absent, body covered by cuticle,

ii)Foot-Absent or if present then reduced to a ventral ridge.

iii)Head-Poorly marked and without eyes or sensory tentacles.

Examples—

Chaetoderma sp, Neomenia sp.

Q.Give salient features of class Gastropoda. Give two suitable examples.

i)Torsion- Visceral mass is twisted at 180⁰ in an anticlockwise direction, relative to the head and foot.

ii)Shell-Is one piece and asymmetrically spiralled.

iii)Head distinct with one or two pairs of tentacles and eyes.

Example- Pila sp, Achatina sp.

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PILA SP

ACHATINA SP

Respiration in Pila
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PHYLUM ECHINODERMATA
General Characters

Q.Give salient features of Phylum Echinodermata.

1.Habitat- Exclusively marine.

2.Body symmetry- Adult with radial and five-rayed symmetry (while larvae are bilaterally symmetrical).

3.Body axis- Body distinguishable in to oral and aboral surface.

4.Body surface- Covered with calcareous ossicles/ plates (Spines/ tubercles often may present).

5.Ambulacral groove- Radiating from the mouth to the tip of the arms, with intervening interambulacra.

6.Digestive system- Digestive canal is mostly coiled tube with aborally placed anus .

7.Water vascular system- Derived from the left mesocoel (left hydrocoel) and partly from the left protocoel

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Classification up to Classes

Q.Distinguish between Asteroidea and Ophiuroidea.

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ASTERIAS SP

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OPHIOTHRIX SP

Water-vascular system in Asteroidea

Q.Give salient features of WVS in Asteroidea.

1. Ring canal-Single; encircling the mouth ; with folded walls.

2.Radial canals- Usually 5 in numbers; lies in ambulacral grooves.

3.Lateral canals- Appear as branches from radial canal on it’s either sides; number corresponds to those of tube-foot; Valve present between radial and lateral canals.

4.Tube feet-Pointed in young, but in adult they terminate in a suctorial disc-like expansions; pointed feet are tactile, while suctorial ones are adhesive.

5.Stone canal-

6.Madriporite-

7.Tiedmann’s body-

8.Polian vesicle-

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PROTOCHORDATES
General Characters
Amphioxus—
Pharynx

Q.Make a brief note on structural components of pharynx of Amphioxus involved in feeding.

i) Cylindrical and highly compressed chamber.

ii)Extended from mouth nearly to anterior half of the body.

iii) Only dorsal side of pharynx is united.

iv)Atrium encloses pharynx on all sides except the dorsal.

v)Atripore located posteriorly.

vi) Lateral wall of pharynx is perforated by obliquely arranged vertical gill slits.

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Q.State the feeding mechanism involved in Amphioxus.

 

(Key points:)

Cilia present in stigmata beat to drive out water current from pharynx to atrium to exterior to maintain water current through mouth.

Trapping of food particles: By sticky secretion of mucous cells from endostyle..

Passage of food rope: Mucous entangled food – peripharyngeal ciliary groove – epipharyngeal grooves --esophagus, as a food rope.

Resisting entry of unwanted large particles: By buccal cirri around the mouth.

Receptor for testing water current: Receptor organs, located on velum and atrium.

Regurgiation of unwanted water-current: Performed by closing the atriopore and contracting the pharyngeal musculature.

Nervous regulation: Afferent and efferent nerve fibers regulated by beating of cilia.

 
AGNATHA
General Features
Classification of cyclostomes up to classes
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PISCES
General Features
Classification up to orders
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Osmoregulation in Fishes
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Q.What do you mean by sodium and chloride pumping mechanism in freshwater teleosts?

This pumping mechanism can be explained uder the following major points—

i)The active uptake of ions from the ambient water requires ATP. Thus active ion uptake places demands on an animal’s energy resources.

ii)The mechanisms that pump Na+ and Cl- from the ambient water into the blood are typically different and independent from each other.

iii)The Cl- pump typically exchanges bicarbonate ions (HCO3-) for Cl- ions, in this way remaining electroneutral.

iv)The Na+ pump typically exchanges protons (H+) for Na+ ions(or possibly exchanges NH4+ for Na+ in some groups of animals, thereby remaining electroneutral.

v)The HCO3- pumped from the blood into the ambient water by the Cl- pump and the H+ pumped outward by the Na+ pump are produced by aerobic catabolism. The HCO3- and H+ ions are formed by the reaction of metabolically produced CO2 with H2O. Thus Na+and Cl- pumps participate in removal of metabolic wastes.

vi)Because HCO3- and H+ are principal layers in acid-base regulation, the Na+ and Cl- pumps sometimes play critical roles in the acid-base physiology of freshwater animals.

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ION EXCHANGE MEDIATED BY ACTIVE Na+ AND Cl- TRANSPORT IN THE GILL EPITHELIUM OF FRESHWATER TELEOST FISH.

 
AMPHIBIA
General Characters

Q.Give salient features of Amphibia.

1.Body- with distinct head and elongated trunk.

2.Skin- highly glandular, moist and in some dermal scale may present (Apodas).

3.Limb- two pairs of pentadactylous.

4.Status of thermoregulation-ectothermic.

5.Circulatory system- with 3 chambered heart and nucleated RBC.

6.Excretory system- mesonephric (in salamandars) or opisthonephric (in caecilians).

7.Pattern of vertebrae-procoelous.

8.Skull- dicondylic (with two occipital condyles); absence of supra occipital and basioccipital (present in mammals).

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Classification up to orders

Q.Distinguish between Anura and Caudata.

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BUFO SP

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CRYPTOBRANCHUS SP

Parental care
Metamorphosis in Toad
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Q.Define metamorphosis.

Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Metamorphosis is iodothyronine-induced and an ancestral feature of all chordates.

 

Q.Make a list of progressive changes involved in metamorphosis of toad.

i)The external gills of the newly hatched tadpole are covered with a gill sac after a few days, and lungs are quickly formed. Front legs are formed under the gill sac, and hind legs are visible a few days later. Ii)Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Tadpoles use a relatively long, spiral‐shaped gut to digest that diet.

iii)Rapid changes in the body can then be observed as the lifestyle of the frog changes completely.

iv)The spiral‐shaped mouth with horny tooth ridges is resorbed together with the spiral gut.

v)The animal develops a big jaw, and its gills disappear along with its gill sac. Eyes and legs grow quickly, a tongue is formed, and all this is accompanied by associated changes in the neural networks.

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REPTILES
General Characters

Q.State salient features of class reptilian.

i)Skin is dry, cornified and usually covered by epidermal scales or scutes.

ii)Nostril—Single and present on the snout.

iii)A post anal tail is present.

iv)The heart is composed of 2 auricles and a partially divided ventricle.

v)Kidney—metanephric type.

vi)Cranial nerves—12 pairs.

vii)Occipital condyle—Single and present for the attachment with atlas.

viii)fertilization—internal.

 

Q.Distinguish between anapsida and diapsida.

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CHELONE SP

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SPHENODON SP

Classification up to orders

Q.Give the systematic position of Hemidactylus sp (mentioning characters of its respective order)

Phylum:Chordata

Subphylum:Vertebrata

Superclass:Gnathostomata

Class:Reptilia

Subclass:Lepidosauria

Order:Squamata (According to J.Z.Young , 1981)

Order character—

i)Skull—With superior temporal fossa.

ii)Pattern of vertebrae—Procoelous type, with chevron bone.

iii)Cloacal aperture—Transverse.

iv)Organ of Jacobson—Well developed.

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Poisonous and non-poisonous snakes
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Q.What does proteroglyph mean?

Snakes those have permanently erect grooved poison fangs, with ordinary teeth behind them in the jaws. It includes the cobras, Kraits, and the sea snakes (Elapidae). It includes the following features—

i.Location of Poison groove – all along the surface.

ii.Located in front of maxilla & oftenly with several small solid teeth behind the fangs.

iii.Fangs are extremely and permanently erect.

iv.The fangs are each connected by a venom duct to a venom gland.

v.They use muscular contraction of the venom gland to inject the venom into the prey.

vi.Rigid fangs fit into pockets in the outer gum of the lower jaw.

Q.Give scientific names of two poisonous and two nonpoisonous snakes found in India.

 

Poisonous snakes:

i)Common Krait (Bungarus caeruleus), ii)Indian cobra (Naja naja), iii)Russell’s Viper (Vipera russelli)

Non-poisonous snake:

i) checkered keelback or Asiatic water snake (Xenochrophis piscator), ii) The buff striped keelback (Amphiesma stolatum)

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Biting mechanism

Q.Describe the kinetic skull of viperidae snake.

Cranial kinesis is the term for significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw. It is usually taken to mean relative movement between the upper jaw and the braincase.

i)All viperids [e.g; Rattlesnake (Crotalus atrox)]have a pair of relatively long solenoglyphous (hollow) fangs that are used to inject venom from glands located towards the rear of the upper jaws, just behind the eyes. Each of the two fangs is at the front of the mouth on a short maxillary bone that can rotate back and forth.

ii)The left and right fangs can be rotated together or independently. During a strike, the mouth can open nearly 180° and the maxilla rotates forward, erecting the fangs as late as possible so that the fangs do not become damaged, as they are brittle.

iii)The jaws close upon impact and the muscular sheaths encapsulating the venom glands contract, injecting the venom as the fangs penetrate the target. This action is very fast; in defensive strikes, it will be more a stab than a bite.

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Q.Give an account of venom transferring mechanism in poisonous snake.

i)During the contraction of digastrics muscle the posterior ligament is relaxed and during the during the rotation of the squamosal bone the fan-shaped ligaments are stretched to squeeze the walls of the gland.

ii)This makes the poison to come out of the gland through the duct and fang.

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AVES
General Characters

Q.What are the major types of down feather?

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Q.Give characteristic features of a bird skull.

i)Similar to that of Archosaurian reptiles. Individual bones can be recognized in the young, but they mostly become united in the adult to form a continuous thin walled structure that encloses the brain and sense organs and supports the beak.

ii)Incomplete secondary bony palate (complete in Mammals).

iii)The large size of the brain and reduction of its olfactory portions are responsible for the rounded form of the top of the head and there are very large orbits at the sides, separated by an ossified septum.

iv)The base of the skull is formed by a basioccipital behind, carrying a single occipital condyle. There is a large besisphenoid covered ventrally by a pair of besitemporals.

Classification up to orders

Q.Name the orders of the following birds (mentioning respective taxon characters)

(a)Ducks, (b) Cuckoos.

(a) Anseriformes:

i)Specialized for aquatic life with flattened bills ,used to feed on various diets.

ii)Some are vegeterians ,a few filterfeeders ,some eat molluscs and other fish.

iii)Eggs are numerous and usually white or pale.

iv)Nest is usually built on the ground.

 

(b)Cuculiformes:

i)Build nests but many lay their eggs in those of other birds.

ii)The eggs are strongly mimetic with those of the host ,variable in colour.

iii)The young hatch before the host eggs ,which are then ejected from the nest by the young cuckoo.

Q.Give salient feature of Apodiformes and give suitable example of this order.

i)Fully adapted in the air than any other birds. The wings are very long ,composed of a short humerus and long distal segments.

ii)They are insectivorous and have very large mouths adapted for feeding on the wings.

iii)The nests are often made in holes.

Examples— Swifts and humming birds.

Flight adaptations
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MAMMALS
Classification up to orders

Q.Name the order of Ornithorhynchus sp (mentioning its order characters)

Order name— Monotremata

i)Body covered with a dense soft fur,protected by spiny outer fur.

ii)Sweat & sebaceous gland, beaks or snout, nictating membrane present.

iii)Digits end in sharp claws and usually webbed.

iv)Cloaca present into which rectum and urinogenital system open.

v)Occipital condyle—narrow and more elongated antero posteriorly than transversely.

vi)Vertebral column:

Cervical (7), thoraco lumber (19), sacral(2-4) and caudal (variable); Epiphysis- ill developed except in caudal region; zygapophysis absent in cervical region.

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Integument and its modification—
Hair
Horn

Q.Give characteristic feature of prong horn.

i)It consists of a conical projection on the frontal bone.

ii)A horny epidermal sheath covers the projection.

iii)The sheath usually bears one side projection or prong, but as many as three have been encountered.

iv)The epidermal sheath is shed with annual periodicity and a new epidermal sheath again covers the bony projection.

v)This is a unique type of horn found only in the antelope (Antelocapra americana).

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Antler

Q.Distinguish between horns and antlers.

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Nail
Claw
Origin & distribution of Cranial nerves in Cavia
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