Dr PS Verma VK Aggarwal Class 9 Biology 4th Chapter Diversity In Living Organisms Solution

Dr PS Verma Dr. VK Aggarwal Solution Class 9 Biology 4th Chapter – “Diversity In Living Organisms” in here.

Short Answer Type Questions Answers (Carrying 2 marks each) Page No. 259

(1) Various types of species diversity are:-

(i) Point diversity

(ii) Alpha diversity

(iii) Gamma diversity

(iv) Epsilon diversity

(2) Point diversity:- This is a diversity present on the smallest scale, i.e., the diversity of micro habitat.

Alpha diversity: Also known as local diversity and includes variety of organisms local to a particular habitat.

Gamma diversity: It represents the diversity of a larger unit such as an island or a landscape.

Epsilon diversity:- It is also called regional diversity and includes total diversity of a group of gamma diversity areas.

(3) The need for classification:

(i) Classification makes the study of a wide variety of organisms easy.

(ii) Classification projects before us a picture of all life forms at a glance.

(iii) It is essential to understand the interrelationships among different groups of organisms.

(4) The method of arranging organisms into groups or sets on the basis of similarities and differences is called classification.

(5) There are 2 broad categories of cell structure: Prokaryotic and Eukaryotic. Thus, two broad groups can be formed – one having prokaryotic cell structure and the other having eukaryotic cell structure.

(6) The seven categorized of hierarchical classification are:-

Species, Genus, Family, Order, Class, Phylum, Kingdom.

(7) (i) Plants have less definite shape and size whereas, animals have definite shape and size.

(ii) Plants are usually branched whereas animals are unbranched except for sponges.

(iii) Plant organs are generally external whereas Animal organs are generally internal.

(8) Two disadvantages of two kingdom classification are follows:- (i) Many protozoans possess characters of both plants and animals. For example, Euglena has animal characters but it contains chlorophyll.

 

(ii) Bacteria and Cyanobacteria (blue-green algae) have many similarities between them and are quite different from other organisms. Thus, it is difficult to place them in their plant or animal kingdom

(9) Follow the Book

(10) (i) This group includes many kinds of unicellular eukaryotic organisms such as unicellular eukaryotic organisms such as unicellular algae, protozoans and unicellular fungi.

(ii) Their mode of nutrition can be autotrophic or heterotrophic.

(11) (i) Lichens grow as the slow growing coloured patches on rocks, bark of tree trunks, and even on the ground. They are very hardy.

(ii) In lichens, blue green algae or cynobacteria and fungi live in symbiosis.

(iii) The algal component of the lichen is known as phycobiont and the fungal component as mycobiont.

(12) Follow the book

(13) Four general character of Thallophyta are follows:

(i) Usually contain green pigment for photosynthesis, some algae have other photosynthetic pigment such as red, brown and purple. This pigments form the basis of further classification of algae.

(ii) They are autotrophic.

(iii) They have cellulose cell wall around the cell.

(iv) Sex organs are simple, single celled and there is no embryo formation after fertilization.

(14) The difference between algae and fungi are followed:-

(i) Algae contain photosynthetic pigments whereas, In Fungi, Photosynthetic pigment are absent in them.

(ii) Algae are autotrophic whereas Fungi are heterotrophic.

(15) The four characteristics of Algae are :-

(i) They contain photosynthetic pigment.

(ii) Algae are autotrophic.

(iii) Most of the algae are aquatic in habitat.

(iv) The cell wall is made of cellulose.

16) The difference between dicots and monocots are following:-

(i) In the account of Dicots, Their leaves have reticulate venation with a network of veins. Whereas, In Monocots, their leaves have parallel venation.

(ii) In Dicot, The root system has a prominent tap root whereas, In Monocots the root system consist of similar fibrous root.

(17) The difference between Bryophyta and Pteridophyta are follows:

(i) Bryophyta plant body is gametophytic whereas, Pteridophyta plant body is sporophytic.

(ii) Bryophyta plant body is either thallose and/or folliose. However, real stem and leaves are always absent. Whereas, Pteridophyta plants real stem and leaves are present.

(18) The four main characters of Bryophyta are:-

(i) Bryophyta plant body is gametophytic.

(ii) Bryophyta plant body is either thallose and/or folliose. However, real stem and leaves are always absent.

(iii) Fixation of plant body is carried out by rhizoids.

(iv) Sporophyte is parasitic over the gametophytic plant body throughout its life.

Two Examples of Bryophyta are: Riccia, Marchantia.

(19) The four main characters of Pteridophyta:

(i) Pteridophyta plant body is sporophytic.

(ii) Pteridophyta plants real stem and leaves are present.

(iii) Fixation of plant body is carried out by roots.

(iv) Pteriodophytes are vascular plants.

Two example of Pteridophyta: Club mosses-Selaginella, Lycopodium.

(20) The four main characters of Gymnospermae are follows:

(i) They are most primitive and simple seed plants.

(ii) The seeds produced by these plants are naked and are not enclosed within fruits.

(iii) Usually perennial, evergreen and woody plants.

(iv) Sporophylls are aggregated to form cones. There are separate male and female cones.

Two examples are: Cycas, Pinus.

(21) The four main characters of angiosperms:

(i) Sporophylles are aggregated to form flowers.

(ii) The seeds are enclosed by a fruit wall.

(iii) Microspores and megaspores are produced in the same or different types of flowers.

(iv) The ovules are enclosed within an ovary.

(22)  The difference between Non-Chordata and Chordata are following:-

Nonchordates Chordates
(i) Notochord is absent in them. (i) Notochord is present in them at some of their developmental stage.
(ii) Their central nervous system is solid and ventral. (ii) Their central nervous system is hollow and dorsal.

(23) Porifera have a cellular level of organization whoever, Cnidaria have a tissue level of organization.

Porifera’s bodies have a number of inhalent whereas, Cnidaria’s bodies have only a single opening.

Digestion of Porifera is intracellular whereas, Digestion of Cnidaria is both extracellular and intracellular.

(24) Polyp is a cylinder with tentacles at the top. The Hydra looks like a tin can with slender arms coming from the top of its body. This body form does not move and the animals are trappers.

Medusa is an umbrella shaped structure with tentacles hanging down from it. The jellyfish is an example. These animals move. During the reproductive stages of the jellyfish there is a time when they take on the polyp form. Then they bud off and become medusa.

(25) The four general characters of Porifera are:-

(i) Simplest multicellular, diploblastic animals.

(ii) The body design involves minimal differentiation and division into tissues. The cells are loosely held together in a gelatinous matrix, mesoglea or mesohyl and do not form tissues.

(iii) Mouth, digestive cavity and anus absent.

(iv) Skeleton is made up of minute calcareous or silicious spicules or sponging fibre or both.

Two example of Porifera: Leucosolenia, Spongilla.

(26) The four general characters of Coelenterates are following:

(i) aquatic, Mostly marine, a few such as Hydra are fresh water. Some of these species live in colonies while other live in solitary.

(ii) Body shows radial symmetry.

(iii) respiratory, circulatory and excretory organs are absent.

(iv) The system of Nervous is primitive, has only network of nerve cells.

Two example of Coelenterates: Hydra, Corel, Rhizostoma.

Page No. 260

(27) The difference between Bilateral Symmetry and Radial Symmetry are following:

(i) Limbs and organs are paired whereas Limbs and organs occur all around the central axis.

(ii) In Bilateral symmetry, cephalization is present whereas, In Radial symmetry cephalization is absent.

(28) Four characteristics of Ctenophora are discuss below:-

(i) Transparent body with biradial symmetry.

(ii) Two tentacles and eight longitudinal rows of ciliary comb-plates for locomotion are absent.

(iii) Marine, Solitary and free swimming.

(iv) No polymorphism or dimorphism occurs.

Two example of Ctenophora: Cestum, Beroe.

(29) The four main character of Platyhelminthes are followed:

(i) Bilaterally symmetrical and dorsoventrally flattened animals.

(ii) Body thin, soft, leaf-like or ribbon like.

(iii) Digestive cavity with a single opening, the mouth.

(iv) Suckers and Hooks are usually present.

Two example are:- Dugesia, Planaria.

(30) The four main characters of Nematoda are follows:

(i) Bilaterally symmetrical, triploblastic, pseudocoelomate and unsegmented animals.

(ii) Body is worm-like, cylindrical or flattened.

(iii) Body is covered with a tough, resistant cuticle; cilia absent.

(iv) sexes are separate.

(31) The four main characters of Annelida are follows:

(i) Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform and cylindrical or disoventrally flattened.

(ii) Exoskeleton absent; body is covered by a thin cuticle.

(iii) Locomotory organs are segmentally arranged paired lateral appendages, parapodia or chitinous setae or chaete.

(iv) Reproduction is by sexual means. Sexes may be united or separate.

Ex: Nereis, Hirudinaria.

(32) Hermaphrodite is an individual which has both type of sex organs.

Ex: Liver fluke, tape-worm.

(33) Triploblastic: They are animals having three germinal layers – outer ectoderm, middle medoderm and inner endoderm. Ex. Liver fluke / Ascaris / Star fish.

(34) A coelomate animal is the one which has a body cavity in which well developed organs can be accommodated.

Ex: Earthworm and Hirudinaria.

(35) Four general characters of Phylum Arthropoda:-

(i) Triploblastic, bilaterally symmetrical and metamerically segmented animals.

(ii) Exoskeleton of cuticle, containing protein, lipid, chitin and often calcium carbonate is secreted by underlying epidermis and shed at intervals.

(iii) They have complex muscular system, with exoskeleton for attachment, striated muscles for rapid actions and smooth muscles for visceral organs. Cilia are absent.

(iv) Sexes are usually separate, sexual dimorphism is well marked in several forms.

Examples: Peripatus, Palaemon.

(36) Four general characters of Phylum Mollusca:

(i) Body is soft, bilaterally symmetrical, with little segmentation and without appendages. The size of body varies from a microscopic to a giant form.

(ii) Body cavity is haemocoel. True coelom is reduced and restricted to the pericardial cavity and the lumen of the gonads and nephridia.

(iii) Digestive tract has a simple structure.

(iv) Sexes are usually separate.

Example: Chiton, Pila.

(37) Four characters of Echinodermata are follows:-

(i) Simple animals may be star like, spherical or elongate.

(ii) Body triploblastic, coelomate, unsegmented and radially symmetrical

(iii) Body lacks head, but has oral and aboral surfaces. Oral surface of body  has five radial areas called ambulacra.

(iv) Body wall is covered with spiny hard calcareous plates that forms a rigid or flexible endoskeleton.

Ex. Antedon, Holothuria.

(38) (a) Prawn>>>>Palaemon.

(b) House fly>>>>>Musca.

(c) Star fish>>>>>>Asterias.

(d) Squid>>>>>>Loligo.

(e) Apple snail>>>>>Pila.

(f) Fresh water mussel>>>>>>Unio.

(39) Echinodermata.

Function:

The ambulacral system is the locomotive apparatus of the Phylum Echinodermata (sea-urchins, star-fishes, etc), the most important feature of which is the protrusible tube-feet that the animals can dilate with water at will, and thus move forward.

(40) (i) Their body is boat shaped or stream lined.

(ii) Their Head, body and tail are compressed to make it suitable for locomotion in water.

(iii) The pelvic fins, pectoral fins, dorsal fin, anal and caudal fins act as paddles and control the direction of movement in water and provide balance.

(iv) The breath organs gills are well developed and suited for gaseous exchange in water. etc.

(41) For characteristics of Chondrichthyes are :-

(i) They are generally large in size .

(ii) Stremlined body is either laterally compressed and spindle-shaped or dorsoventrally flattened and disc shaped.

(iii) Mouth is ventral in position.

(iv) Skin is tough and covered with minute placoid scales.

Examples are: Dog fish, Electric ray.

(42) Four characteristics of Osteichthyes are:-

(i) Size varies from 10 mm to 4 meters.

(ii) Body is generally spindle shaped.

(iii) Skin is open and covered with cycloid or ctenoid scales.

(iv) Mouth is usually terminal in position.

Examples are: Angler fish, Mandarin Fish.

(43) Bony fishes And Cartilaginous fishes:

(i) Bony fishes have bony endoskeleton whereas, Cartilaginous fishes have cartilaginous endoskeleton.

(ii) Bony fishes contain four pairs of gill slits whereas, Cartilaginous fishes contain five to seven pairs of gill slits.

(ii) Amphibia and Reptilia:

(i) Amphibia includes frogs, toads, newts and salamanders whereas, Reptilia includes lizards, snakes, crocodiles, tortoises etc.

(ii) Amphibia’s body has a distinct head and trunk and has no neck. Mouth is usually large whereas, Reptilia’s body varies in form and is usually divided into head, neck, trunk and tail.

(iii) Aves and Mammals:

(i) In Aves, Larynx of birds is non functional. Instead syrinx is present whereas, In Mammals, Larynx of mammals is functional. Syrinx is absent.

(ii) In Aves Lungs contain external air sacs whereas, In Mammals external air sacs do not occur in lungs.

(44) The four characters of mammals are following:

(i) Mammals are warm blooded.

(ii) Body is divisible into head, neck, trunk and tail.

(iii) Females have milk producing mammary glands which secrete milk for the nourishment of the young.

(iv) A muscular diaphragm separates thoracic and abdominal cavities.

Ex: Bat, Squirrel.

(45) Some flight adaptation of birds are followed:

(i) Forelimbs are modified into wings.

(ii) Body is covered with exoskeleton of waterproof and lightweight feathers.

(iii) Long bones of endoskeleton are pneumatic having air cavities.

(iv) Body is streamlined to reduce air resistance during its flight.

(46) The four main character of Chordates are followed:

(i) Notochord is present in them at some of their development stage.

(ii) Their central nervous system is hollow and dorsal.

(iii) Heart is always present and it is ventral in position.

(iv) Their circulatory system is of closed type.

(47) Protochordata are bag like, sessile. Soft bodied, non metameric animals. The adult body is covered with a tunic or test containing cellulose.

Ex: Oikopleura, Herdmania.

(48) Urochordata: Herdmania.

Cephalochordata: Branchiostoma.

(49) Difference between Notochord and Nerve Cord:

Notochord is a transient mesodermal rod in the most dorsal portion of the chordate embryo.

Nerve cord is a collection of nerve fibres that runs throughout the length of an animal.

Long Answer Type Questions (Carrying 5 marks each) Page No 260

(1) Here I am mentioned one by one characteristics used in hierarchical classification of organisms:-

(i) Species: It is a basic unit for understanding taxonomy as well as evolution. Species is a group of individuals with similar morphological characters, which are able to breed among themselves and produce fertile off springs of their own kind.

(ii) Genus: It is a group of species which are related and have less characters in common as compared to species.

(iii) Family: It is represented by a group of related genera that are more similar to each other than with genera of other families.

(iv) Order: It is an assemblage of families resembling one another in a few characters.

(v) Class: It represents organisms of related orders.

(vi) Phylum: It includes all organisms belonging top different classes having a few common characters.

(vii) Kingdom: It includes all organisms who share a set of distinguishing common characters.

(2) The importance of classification are following:

(i) Classification makes the study of a wide variety of organisms easy.

(ii) It projects before us a picture of all life forms at a glance.

(iii) Classification essential to make out the interrelationships among groups or organisms.

(iv) It forms a base for the development of other biological sciences.

(3) Linnaeus’s scheme of arranging organisms into an ascending series of group of ever-increasing inclusiveness forms the hierarchical system of classification.

The categories in the hierarchy are placed in ascending order. As we go upwards from the species to the kingdom.

(i) Species: It is a basic unit for understanding taxonomy as well as evolution. Species is a group of individuals with similar morphological characters, which are able to breed among themselves and produce fertile off springs of their own kind.

(ii) Genus: It is a group of species which are related and have less characters in common as compared to species.

(iii) Family: It is represented by a group of related genera that are more similar to each other than with genera of other families.

(iv) Order: It is an assemblage of families resembling one another in a few characters.

(v) Class: It represents organisms of related orders.

(vi) Phylum: It includes all organisms belonging top different classes having a few common characters.

(vii) Kingdom: It includes all organisms who share a set of distinguishing common characters.

 

(4) Kingdom Monera

The kingdom prokaryotae is divided into two sub-kingdoms. Archaebacteria, Eubacteria.

Archaebacteria: Most Archaebacteria are autotrophs and only a few, photosynthesize. Archaebacteria derive the energy for their metabolic activities, from the oxidation of chemical energy sources, such as the reduced gases – ammonia, methane or hydrogen sulphide. In the presence of one of this chemical Archaebacteria can manufacture their own amino acids and proteins.

Archaebacteria are divided into three groups: Methanogens, Thermoacodophiles, Halophiles.

Eubacteria: Prokaryotic cells of bacteria have an outer cell wall that surrounds the plasma membrane, which in turn surrounds a noncompartmentalised cytoplasm dotted with ribosomes. They generally lack membrane enclosed organelles such as nucleus, chloroplast and mitochondria.

Eubacteria are divided into eight groups: Actinomyces, Chaemoautotrophs, Cyanobacteria, Enterobacteria, Gliding and Budding bacteria, Pseudomonas, Rickettsias and Chalmydias, Spirochaetes.

(5) The main characteristics are:

(i) This group includes many kinds of unicellular eukaryotic organisms such as unicellular algae, protozoans and unicellular fungi.

(ii) These organisms use appendages, such as hair like cilla or whip like flagellum.

(iii) Their mode of nutrition can be autotrophic or heterotrophic.

Example: Unicellular Algae, Chlorella.

(6) Kingdom Fungi:- Simple non-green plants which are not photosynthetic. They are heterotrophic and eukaryotic organisms.

They may be unicellular or filamentous.

Fungi have a cell wall containing a mixture of chitin and cellulose.

The reserve food is glycogen.

Ex: Bread mould, Yeast etc.

(7) The division Spermatophyta, includes all seed bearing plants. It has been divided into two sub divisions-

>>Gymnosperms

>>Angiosperms.

 

Gymnosperms: The gymnosperms are seed producing land plants. However, the seeds are not enclosed in fruits. Most of them have now become extinct and only about 900 species are known to be surviving. The living gymnosperms are widely distributed in the cold climates where snow, rather than rain, is the source of water. Only one group called cycads thrive in warmer regions.

Angiosperms: Angiosperms represent the most advanced group of vascular plants. They are commonly called ‘Flowering plants’. They exceed all other major groups of living plants in number and diversity.

(8) Pteridophyta: (Gr., pteris, – idos – fern)

This type of plants mainly found in shady and damp places. The plant body is made up of root, stem and leaves. They have well developed vascular system for the conduction of water and other substances, from one part of the plant body to another. These types o0f plants have no flowers and do not produce seeds.

The difference between Bryophyta and Pteridophyta are follows:

Bryophyta Pteridophyta
Body is gametophytic Body is sporophytic.
Plant body is either thallose and/or folliose. Real stem and leaves are present.
Fixation of plant body is carried out by rhizoids. Fixation of plant body is carried out by roots.
Non vascular in nature Vascular in nature

(9) The General characteristics of Platyhelminthes are followed:

(i) Bilaterally symmetrical and dorsoventrally flattened animals.

(ii) Body thin, soft, leaf-like or ribbon like.

(iii) Digestive cavity with a single opening, the mouth.

(iv) Suckers and Hooks are usually present.

Two example are:- Dugesia, Planaria.

The general characteristics of Nematoda are follows:

(i) Bilaterally symmetrical, triploblastic, pseudocoelomate and unsegmented animals.

(ii) Body is worm-like, cylindrical or flattened.

(iii) Body is covered with a tough, resistant cuticle; cilia absent.

(iv) sexes are separate.

Two example of Nematoda: Ascaris, Ancylostoma.

(10) The general characteristics of Annelida are follows:

(i) Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform and cylindrical.

(ii) Body is metamerically segmented externally by transverse grooves and internally by speta. Some of the anterior body segments concentrate to form head.

(iii) Exoskeleton absent.

(iv) Body is covered by a thin cuticle.

(v) Alimentary canal is tube like, complete and extends from mouth to anus.

(vi) Sexes may be united or may be separate.

Phylum Annelida includes the following three classes:

Class 1. Polychaeta.

Ex. Nereis, Aphrodite.

Class 2. Oligochaeta

Ex. Phertima, Eutypheus.

Class 3. Hirudinea

Ex. Hirudinaria.

(11) General characteristics of Phylum Mollusca:

(i) Body is soft, bilaterally symmetrical, with little segmentation and without appendages. The size of body varies from a microscopic to a giant form.

(ii) Body cavity is haemocoel. True coelom is reduced and restricted to the pericardial cavity and the lumen of the gonads and nephridia.

(iii) Digestive tract has a simple structure.

(iv) Sexes are usually separate.

Example of each class of Mollusca

(i) Gastropoda: Pila (apple snail).

(ii) Pelecypoda: Unio (fresh water mussel).

(iii) Cephalopoda: Loligo (squid).

(12) General characteristics of Phylum Arthropoda:-

(i) Triploblastic, bilaterally symmetrical and metamerically segmented animals.

(ii) Exoskeleton of cuticle, containing protein, lipid, chitin and often calcium carbonate is secreted by underlying epidermis and shed at intervals.

(iii) They have complex muscular system, with exoskeleton for attachment, striated muscles for rapid actions and smooth muscles for visceral organs. Cilia are absent.

(iv) Sexes are usually separate, sexual dimorphism is well marked in several forms.

Example of each class of Phylum Arthropoda

(i) Crustacea: Palaemon (prawn)

(ii) Myriapoda: Scolopendra (centipede)

(iii) Insecta: Lepisma (Silver fish)

(iv) Arachnida: Limulus (king crab)

(13) The major phyla of animal kingdom are follows:

Phylum 1. Porifera

Phylum 2 Coelenterata

Phylum 3 Ctenophora

Phylum 4 Platyhelminthes

Phylum 5 Nematoda

Phylum 6 Annelida

Phylum 7 Arthropoda

Phyllum 8 Mollusca

Phyllum 9 Echinodermata

Phyllum 10 Hemichordata

Phyllum 11 Chordata

Phylum Porifera – Sessile, sedentary, and marine except one group that lives in fresh water. These are non-motile animals attached to some solid support.

Example: Sponges

Phylum Coelenterata – Cnidarians or coelenterates are multicellular, diploblastic animals with tissue grade of organisation. A gelatinous layer called mesoglea persists between the ectoderm and endoderm.

Example: Aurelia (jelly-fish)

Phylum Ctenophora: Their body is transparent with biradial symmetry, as well as 2 tentacles and 8 longitudinal rows of ciliary comb-plates for locomotion are present.

Example: Pleurobrachia, Cestum.

Phylum Platyhelminthes – Bilaterally symmetrical and dorsoventrally flattened animals with a soft, leaf-like or ribbon-like thin body.

Example: Taenia Solium (pork tape-worm)

Phylum Nematoda – Bilaterally symmetrical, triploblastic, pseudocoelomate and unsegmented animals. Body is worm-like, cylindrical or flattened.

Example: Ascaris (round-worm)

Phylum Annelida – Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform and cylindrical or dorsoventrally flattened, exoskeleton absent; body is covered by a thin cuticle.

Example: Hirudinaria (Indian cattle leech)

Phylum Arthropoda – Body segments are grouped into two regions – cephalothorax (head and thorax together) and abdomen, or three regions – head, thorax and abdomen. Anterior part of body forms a distinct head, bearing sense organs and brain.

Example: Palaemon (prawn)

Phylum Mollusca – Body is soft, bilaterally symmetrical, with little segmentation and without appendages. The size of body varies from a microscopic to a giant form such as Octopus of upto 50 feet.

Example: Octopus (devil fish)

Phylum Echinodermata – Simple animals may be a star like, spherical or elongate with body triploblastic, coelomate, unsegmented and radially symmetrical.

Example: Echinus (sea urchin)

Phylum Hemichordata – Body is soft unsegmented worm like and bilaterally symmetrical. These animals possess a combination of invertebrate and chordate characters.

Example: Balanoglossus, Cephalodiscus.

Phylum Chordata – Chordates are characterised by the following three features: (a) a dorsal, hollow, tubular nerve cord; (b) a pliable rod called notochord that occurs ventral to nerve cord and is replaced by a bone or cartilage to form a vertebral column in vertebrates; and (c) paired gill-slits in the pharynx.

 

Example: Fishes

(14) Important characters of Mammals:

(i) Mammals are warm blooded.

(ii) Body is divisible into head, neck, trunk and tail.

(iii) Females have milk producing mammary glands which secrete milk for the nourishment of the young.

(iv) A muscular diaphragm separates thoracic and abdominal cavities.

Ex. Hedge dog, Lion.

Important characters of birds:

(i) Forelimbs are modified into wings.

(ii) Body is covered with exoskeleton of waterproof and lightweight feathers.

(iii) Long bones of endoskeleton are pneumatic having air cavities.

(iv) Body is streamlined to reduce air resistance during its flight.

Ex. Passer, Bubo

(15) The subphylum ‘Gnathostomata’ is divided into 6 different classes. Out of the six two classes, Chondrichthyes and Osteichthyes combine together to form a super-class, called Pisces.

Classify and Explain two different type of fishes:

Cyclostomata:

(i) Body is long, elongated and eel like.

(ii) Skin is soft, slimy smooth and scaleless.

(iii) Mouth is rounded, suctorial and without jaws.

(iv) Heart is 2 chambered.

Ex. Lamprey, Hegfish.

Chondrichthyes:

(i) Marine fishes with completely cartilaginous endoskeleton. They are generally large in size.

(ii) Streamlined body is either laterally compressed or spindle-shaped or dorsoventrally flattened and disc shaped.

(iii) Mouth is ventral in position.

(iv) Skin is tough and covered with minute placoid scales.

(v) Heart is two chambered.

Ex. Dog fish, Sting ray.


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