english-class x-biology-chapter01
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Classification of Plants : Important groups –
Non-Vascular plants – Multicellular Algae –Bryophytes; Vascular plants – Pteridophytes –
Gymnosperms – Angiosperms.
Classification of Animals : Vertebrata – General
Characters; Important classes – Pisces –
Amphibia – Reptilia – Aves – Mammalia.
You have studied the meaning andmportance of classification in your previous class.
You are also familiar with the hierarchy of
classification.
Plants and animals exhibit considerable
diversity at the cellular level. During the evolution
of organisms, diversity has occured in the structure
and functions of the cells. For example, algae are
generally aquatic, and the lower group of algae
are unicellular, filamentous or colonial in their
orms. The higher algae like Kelp and Sargassum
are multicellular. Plants are deep rooted and
widely branched. They have longer life span and
show diversity in reproduction.
You have learnt about the diversity in the
structure and function of the lower plants and
animals in your previous classes. Let us now
study about the classification of higher plants and
animals.
The following scheme represents the major groups of organisms under the
5 kingdom classification :
Diversity of plants and
animalsThe approximate number of speciesso for identified is about 1,672,000.According to modern classificationplants and animals are classifiedinto five major kingdoms Monera,Protista, Mycota, Plantae andAnimalia.
About 9,000 species are identifiedunder Kingdom Monera. The number
of species in Kingdom Protista isabout 59,950. The number ofspecies under Mycota is about100,000. The number of speciesidentified under the KingdomPlantae is about 289,640. The totalnumber of species identified underAnimalia is about 1,170,000.
Major divisions of theKingdom Plantae
Bryophyta - 24,000 species
Pteridophyta - 10,000 species
Gymnosperms - 640 species
Angiosperms - 255,000 species
Remember this
The known number of vertebratespecies under animal kingdom
Pisces - 2,546 species
Amphibians - 204 species
Reptiles - 428 species
Birds - 1,228 species
Mammals - 372 species
1 THE LIVING WORLD
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KINGDOMS
↓
↓ ↓ ↓ ↓ ↓
Monera Protista Mycota Metaphyta Metazoa
(Plantae) (Animalia)
. Bacteria 1. Unicellular 1. Fungi Non Vascular Multicellular AnimalsAlgae Plants (Invertebrates)
2. Blue green 2. Protozoa 1. Multicellular Algae 1. Poriferaalgae 2. Coelenterata
a. Red algae 3. Platyhelminthesb. Brown algae 4. Aschelminthesc. Green algae 5. Annelida
2. Bryophytes 6.Arthropoda7. Mollusca8. Echinodermata
Vascular plants Chordata1. Pteridophytes 1.Pisces2. Gymnosperms 2.Amphibia3. Angiosperms 3.Reptilia
4.Aves5.Mammalia
1.1 MULTICELLULAR ALGAE
You have studied about unicellular algae likediatoms in your previous class. Most of the algaeare multicellular and have a flat plant body calledhallus. These algae are non-vascular plants. Theyare identified under plant kingdam. They areclassified into three groups, namely : Red algae,Brown algae and Green algae.
Ex : Red Algae - Batrachospermum Polysiphonia
Brown Algae - Sargassum, Ectocarpus Green Algae - Spirogyra, Ulothrix
Algae are mostly aquatic. Members of redand brown algae grow attached to rocks, coralsand other plants of the ocean. Members of greenalgae are mostly freshwater forms found in ditches,ponds, lakes and rivers. A few of them are foundn oceans and on lands, or grow attached to otherplants. Algae are capable of carrying out
photosynthesis.
Agar is obtained from a red algacalled ‘Gelidium ’. It is used inbakery and meat packing industry.It is also used as a medium forculturing bacteria.
A red alga called Porpyra is used
as a condiment and in thepreparation of soup.
An alga called Microcystus growsupto 100 feet in length.
Algin is a useful substance obtainedfrom brown alga. It is used in thepreparation of ice cream, chocolates
and in the preparation of a Japanesefood “Kombu”.
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Green algae contain the green pigmentcalled chlorophyll.
In Red algae chlorophyll ‘a’ and ‘b’ pigmentsare found. In addition, a red pigment calledphycoerythrin and a blue pigment called
phycocyanin are found. Hence, the plant bodyshows red colour.
In Brown algae chlorophyll ‘a’ and ‘c’ pigmentsare found. In addition, xanthophyll pigments areound in abundance. Hence, these algae arebrown in colour.
The cellwall of algae is composed of cellulose
and pectin. Usually the cells are uninucleate.
Reproduction takes place both by asexual
and sexual means.
Sexual reproduction takes place by the fusion of male and female gametes.
Asexual reproduction takes place by the production of spores. Vegetative
propagation is by the fragmentation of thallus. Each bit of the thallus will separate
rom the mother plant and grow into a new plant.
Some species of algae arepreserved and used in thepreparation of cattle feed.
The dead bodies of marine algaealong with other dead organisms of
the sea, undergo decay and releasemethane gas.
When algae grow in decaying watertanks, the oxygen liberated will beutilized by microbes and thus watergets purified.
Fig 1.1 - Common examples of green algae
Many types of algae are used inindustrial processes. A giant alganamed Laminaria is used in theproduction of potassium chlorideand iodine.
Cellwall
Chloroplast
Nucleus
Cytoplasm
Spirogyra - A cell enlarged
Cellwall
Nucleus
Cytoplasm
Chloroplast
Ulothrix - A filament
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1.2 BRYOPHYTA
These plants are found both on moist landand in water. Hence, they are commonly calledas amphibians of the plant kingdom.
Bryophytes are multicellular plants having
he features of eukaryotes. The plant body is alattened, thalloid structure and can be differentiatednto stem, leaves and rhizoids. In these plants,oot-like structures called ‘rhizoids’ are present.
Some plants of this group grow horizontallyn the soil. Ex : Riccia (Liverwort) Some plantsgrow vertical to the soil surface. Ex : MossesThey exhibit simple shoot system and leaves).
The common examples of bryophytes are Marchantia, Riccia, Funaria andMosses.
The life cycle of bryophytes includes twosuccessive generations called gametophyte andsporophyte. Gametophytes are gamete producingplants. Sporophytes are spore producing plants.Gametophytes are prominent and larger in sizeand manufacture food with the help of chloroplasts.Sporophytes are smaller in size and depend on
gametophytes for food.
Rhizoids
These are not roots, but only root-like structures. They absorb waterand mineral salts from the soil.
Meaning of ‘Liverwort’
Since the plant body of some of thebryophytes resemble the shape ofliver, they are called ‘Liverworts’
Riccia is a liverwort that occursboth in water and in moist soil. Thegenus includes about 130 species.Marchantia includes about 65species.
Mosses are tiny little plants generallymaking their apearance after the rains.They are found growing on moist walls,tree trunks and on the ground. Whenthey grow in plenty they cover thesubstratum. Mosses found growing onrocks are called rock mosses. Somemosses grow in marshy places and are
called bog mosses.
Fig 1.2 - Common examples of bryophytes
Marchantia : male andfemale plants
Riccia
MossFunaria
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Bryophytes reproduce by sexual and
vegetative methods. During vegetative
eproduction, the thallus breaks into pieces and
each piece grows into a new plant. Sexual
eproduction occurs by the male and female
gametes. Structures called antheridium andarchegonium are found in adult gametophytes.
Male gametes are produced in antheridium, Female
gametes are produced in archegonium.
1.3 PTERIDOPHYTA
Pteridophytes are included in the group
called “tracheophytes”, because they have thevascular tissues (xylem and phloem) to conduct
water and mineral salts. Ferns and other related
plants are called pteridophytes. These are found
n gardens, moist soil, on the walls and in all cool
and shady regions. These are the first terrestrial
plants to develop vascular tissues to transport
ood and water from one part of the plant toanother. The plant body is differentiated into root,
stem and leaves.
Examples : Nephrolepis (fern plant) Selaginella, Adiantum, Lycopodium.
There are two generations in the life cycle namely sporophyte and
gametophyte.
Moss plants are used in packingflowers. In gardens, moss pads areconstructed while growing creepers.
Fig 1.3 - Some examples of PteridophytesSelaginella
Nephrolepis - A fern plant
‘Walking ferns’
Marsilea, Salvenia, Azolla are thefloating ferns of tanks, ponds etc.The leaves of the fern adiantumtouch the ground, develop rootsand become new plants. These arecommonly called ‘Walking ferns’
Ferns are grown for ornamentalpurposes. Fern leaves are used inflower bouquet. Some ferns areused in medicine. Fern plants like
horsetail and club mosses areinvolved in the formation of goodfuels like coal, petroleum etc.
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The adult plant body is a sporophyte. The sporophyte reproduces asexuallyby producing spores. The gametophyte is small but is an independent structurecalled prothallus. Male gametes are produced in antheridium and female gametesare produced in archegonium, both found in the prothallus.
Sexual reproduction involves the fusion of male and female gametes.
1.4 GYMNOSPERMS
Gymnosperms are a group of seed-bearing vascular plants. However, seedsare not enclosed in fruits.
Gymnosperms grow in dry but cold climatic regions. These are perennialand evergreen plants. Ex : Cycas, Pinus.
Some plants of this group are large treesand some are shrubs. The vascular system is welldeveloped with xylem and phloem. The mostprominent feature of these plants is the productionof two kinds of spores namely microspores andmegaspores. They are produced in structurescalled microsporophylls and megasporophyllsespectively.
Meaning of gymnosperms
In Greek - Gymnos = naked
Sperma = seed
Plants having ‘naked seeds’
Cedrus deodara is a gymnosperm.It grows in the Himalayan forests.
Cupresus, Aracaria juneferous and Cycas are grown in gardensfor ornamental purposes.
Sequoia tree grows about 125meters in height and is about 30meters in circumference.
Fig 1.4 - Cycas - A gymnosperm
Cycas :Male plant
Cycas Female plant
Hood
Ovule
Stalk
megasporophyll
Cycas :Microsporphyllsin the male
cone
It is believed that the life span of pinetrees is more than 5000 years. TheBristle cone trees (Pinus aristata ) ofNevada Mountains, U.S.A., are knownto be more than 5,000 years old.
Coniferous trees are the largest, tallestand oldest trees of the world.
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These plants produce multicellularstructure called cones (They are called conesbecause of their shape). They are of twoypes namely male and female cones.
Microsporophylls produce male sex cells and
megasporophylls produce female sex cells.Sexual reproduction involves the fusion ofhese cells to form a ‘zygote’. The zygote iscovered by a thick coat and together theyepresent the seed.
1.5 ANGIOSPERMS
Angiosperms are the most evolved amongplants. In these plants, the seeds are enclosedn a structure called fruit.
Angiosperms are commonly called as flowering plants. They are found inmoist soil, desert, fresh water habitats. Ex : Maize, Coconut, Wheat, Paddy, PearlBarley, Millet, Mustard, Horsegram, Red Gram, Bean etc.
Based on the general organization of the plant body, angiosperms can begrouped into herbs, shrubs and trees.
Vascular tissues are well developed. Flowers are the reproductive organs.Flowers may be produced singly in the axil of the leaf or a cluster of flowers
may be found together. A special branch bearing a cluster of flowers is callednflorescence.
Fig 1.5 - Male and Female cones
of Pinus
male conefemale cone
Meaning of angisoperms
In Greek Angion = capsule
Sperma = seed
The seeds of orchids are very small.The weight of one million seedstogether is only about 0.3 grams.
Flower
Fruit
Petiole
Stem
Root
Femaleflower
Male flowers
Leaf
Stem
Roots
Fruit
B. Maize plantA. Mustard plant
Fig 1.6 - Typical Dicot (A) and Monocot (B) Plants
Leaf
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Seeds are produced in flowers. Seeds are
of two types. 1. Monocotyledonous2. Dicotyledonous. Monocot seeds contain only
one cotyledon (seed leaf) while the dicot seeds
contain two cotyledons. In monocots, during
germination the cotyledon remains below the soil.
n dicots the cotyledons appears above the soil.
In monocot leaves, veins run parallelly. In
dicot leaves, veins are found in the form of anetwork.
Monocot plants have fibrous root system,while dicot plants have tap root system.
What is Bonsai?
The technique of growing dwarf treesis called bonsai. This technique being
the invention of Japanese helps togrow orange, lime, banyan and mango
trees etc. in pots as dwarf trees. Thetrees grown by this method will beof the same height even after 20-30years. They also bear fruits andflowers.
Stigma
Style
Stamen
Petal
Sepal
Ovary
Fig 1.7 Parts of a typical flower
Common trees of Karnataka
Teak, Blackwood, Jackfruit, Nandi,
Honne, Jamun, Sandal, Cinnamon,Red dye tree, Presin, Indian Mast,Gooseberry, Indian beach, Babul,Acacia, Mango, Tamarind andBamboo are some of the commontrees of Karnataka.
Do you know about thespeciality of sandal trees?
Sandal wood tree is an economicallyimportant tree. The scientific name ofthis tree is ‘Santalum album ’. Theroots of this tree are attached to theroots of other plants and absorb therequired food material. The roots areused in treating skin diseases. Sandalcarving is a beautiful art and materials
made out of it are world famous.Sandal oil is also used in themanufacture of scents and oils.
(A)
Parallel venation inmonocot leaf
Fig 1.8 - Venation in angiosperm leavesMonocots are more advanced thandicots from the point of view ofevolution. About 200,000 dicot plantspecies and 55,000 monocot plant
species are identified.
(B)Reticulate venation in
dicot leaf
{PISTIL
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In fibrous root system, the primary root diesbefore the plants mature. Roots develop from thebase of the stem and branch profusely. A singlemain or central root is absent.
In taproot system, the primary root from theadicle of the seed grows to become the main
or central part of the root system. It produces
many secondary and tertiary branches.
1.6 VERTEBRATES
Vertebrates represent a major group among the advanced animals calledchordates. Chordates exhibit the following characteristic features.
. Presence of a solid supporting structure on the dorsal side of the bodycalled notochord.
2. Presence of a dorsal, tubular nerve cord.
3. Presence of openings in the pharynx called gillslits, atleast in the embryonicstages.
Those chordates in which the notochord is replaced in the adult by avertebral column are grouped under vertebrata. All other animals other thanchordates, are described as invertebrates or non-chordates.
You have studied about invertebrates and their classification in your previousclass. Now, we shall study about vertebrates and their classification.
StemSome useful Plants
Vegetable yielding plants
Brinjal, Ladiesfinger, Cucumber,Potato, Onion, Lemon, Gooseberry,Green leafy vegetables.
Oil yeilding plants
Castor, Groundnut, Sun flower, Niger,Ginger,
Fibre yielding plants
Cotton, Jute, Hemp
Spice yielding plants
Coriander, Fenugreek Cumin,Mustard, Pepper, Cardamom, Clove,
Turmeric.
Fruit yielding plants
Banana, Grapes, Apple, Mango,Guava, Water melon
Fodder yeilding plants
Maize, Jowar, Ragi, Paddy, Grasses.
Medicinal plants
Leucas aspera, Ginger, Ocimum
(Tulsi) Eucalyptus, Neem
Bevarages
Tea, Coffee, Cocoa
Fig 1.9 - Types of roots in angiosperms
Stem
Tap root
Fibrous roots
(A) Tap root system (B) Fibrous root system
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Vertebrates are characterised by the
presence of a backbone or vertebral column
which forms a major component of the skeletal
system. The skeletal system consists of hard rigid
structures called bones which provide support to
he body. They also provide surface for theattachment of muscles.
The body is divided into head, trunk and
imbs.
Digestive system consists of mouth, pharynx
oesophagus, stomach, intestine and many
associated glands.
Respiratory organs are well developed. They
are in the form of gills in aquatic forms and lungs
n terrestrial forms.
Heart is ventral in position and is chambered. Excretory organs are in the
orm of a pair of kidneys. Nervous system consists of dorsal tubular nerve cord
which becomes differentiated into brain and spinal cord.
Vertebrates are unisexual. Only sexual reproduction is seen.
Vertebrata is grouped into the following 5 classes.
(1) Pisces (2) Amphibia (3) Reptilia (4) Aves (5) Mammalia
1.61 PISCES
The members belonging to this class are
commonly called fishes.Fishes are aquatic vertebrates with a
streamlined or spindle shaped body. Mouth is athe terminal end of the body. Jaws are providedwith teeth. Skin is covered with scales whichprovide protection. Skin contains mucous glands.Locomotor structures are in the form of paired
and unpaired fins. Paired fins help in balancing
also.
Meaning of chordata
In Greek, Noton = Back
Chorda = Supporting rod
The animals having a dorsalsupporting rod-like structure.
Meaning of vertebrataVertebrae = Series of bones
Vertebrata - Animals having avertebral column
Phylum chordata includes about39,000 species. This is the mostadvanced phylum in the animal
kingdom
Members of the phylum chordatavary in size from fishes less thanhalf an inch, to whales which areapproximately 30 meters in lengthand 150 tons in weight.
Meaning of pisces
In Greek - Pisces means fish
Migration of fishes
The migratory eels travel thousandsof kilometers from Europe to westor from America to east to theirbreeding centres.
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Economic importance of fishes
Many fishes are consumed as food.Oils are obtained from the livers ofshark and cod. These oils are richin vitamins ‘A’ and ‘D’. The driedskin of sharks is used in makingpolishes.
Fig 1.10 - External features of a fish
Nostril
Eye
Dorsal fin
Mouth
Gill cover Pectoral fin(Paired)
Anal fin
Caudal fin
Pelvic fin(Paired)
Sea horse
Ray fish
Flying fish
Saw fish
Hammerheaded fish
Sucker fish
Shark
Fig 1.11 - Types of Fish
Do you know about fish
which do not look like fish?
The body shape of fish is familiarto us. But there are some fish whichdo not look like fish. A familiarexample is Hippocampus . Its snoutresembles the face of a horse,Hence, it is called sea horse. It has
an elongated body and long coiledtail. Sea horse swims vertically.
Strange fishes
A fish called Ostracion has a pairof horns in front of head and eyes!Hence, it is commonly called “Cow
Fish”
Production of electricity infishes
The electric ray fishes have anorgan to produce electricity. Theseorgans produce high voltage currentin the surrounding water. The electric
eel of Amazon can produce anelectricity of 200 volts!
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Digestive system is well developed with an alimentary canal and associated
glands.
Respiration is typically by pharyngeal gills. Heart is two chambered. Fishes
are cold blooded (poikilothermic) animals. Nervous system is well developed
with brain and spinal cord. Internal skeleton is either cartilagenous or bony. Theseare unisexual animals. They reproduce sexually. There is a great diversity in
colour, shape and structure among fishes.
Ex : sharks, saw fish, electric ray fish, hippocampus (sea horse)
1.62 AMPHIBIA
Members of this class are commonly calledamphibians. Amphibians are the first vertebrates
o appear on land. They are adapted living
successfully on both land and in water.
The body is divisible into head, trunk and
imbs. The skin is very soft and moist due to
secretion of mucous glands. Mouth is provided
with jaws. Nostrils are exposed above the mouth.
Fore limbs have four digits while hind limbs have
ive digits each.
Some amphibians are limbless.Ex : Ichthyophis.
Meaning of amphibia
In Greek - Amphi = both
bios = Life
The animals live both in water andon land.
Because of the secretion of mucusin amphibians the skin is always
kept moist. It helps in respirationalso.
Hibernation and Aestivation(Winter sleep and summer
sleep)
In cold weather and in very dryperiods frogs bury themselvesunderground in damp places. These
periods of inactivity are termedhibernation and aestivationrespectively. During these phasesof their life they do not take foodand live only on the stored fat.
Parental care
A toad called Alytes of Europecarries the egg around its hind legstill the tadpoles are about to hatch.
Nostril
Eye
Mouth
Forelimb
Webbed
feet
Hind limb
Fig 1.12 - External features of frog
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It has well developed digestive system with alimentary canal, and associated
glands. Respiration is by gills, skin, buccal cavity and lungs. A three chambered
heart is found. Amphibians are also cold blooded animals. Nervous system is
well developed with a brain, a spinal cord and 10 pairs of cranial nerves and
an autonomous nervous system.
These are unisexual animals. They reproduce sexually. Fertilization is
external.
They lay eggs on stagnant water.
Metamorphosis’ is seen in the life cycle of these
animals. Ex : Frog, Toad, Salamander, Ichthyophis
etc.
1.63 REPTILIAMembers of this class are commonly called
eptiles. These are the first terrestrial vertebrates.
They have an elongated body covered by a dry
skin bearing an exoskeleton of horny scales. Both
orelimbs and hindlimbs have five digits each
pentadactyle).
Some of the reptiles like snakes, are limbless.
Do you know this?
A toad called Pipa of America doesnot have tongue. These toads havenumerous pits on their back andcarry their young ones in the pits.
Ichthyopis is an Amphibian found inburrows. The skin is soft providedwith folds. The female lays eggs inthe soil and coils round her eggsand protect them till they hatch.
Ichthyophis
Salamander
Fig 1.13 Examples of Amphibia
Metamorphosis
The changes which a larva
undergoes in order to become anadult are collectively calledmetamorphosis
Meaning of reptilia
In Latin - repere = to creep
creeping or crawling vertebrates.
External Fertilization
Fertilization takes place in watermedium, outside the body.
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Do you know aboutChameleons?
Chameleon is a lizard. Eyes arecapable of independent movement.This lizard is known for changingits body colour with thesurroundings. It is a self defenceMechanism to escape from itsenemies.
Eye
Fore Limb
Hind Limb
Tail
Fig 1.14 - External features of a garden lizard
Extinct reptiles
Tyranosaur and Dinosaur are thegiant reptiles which existed about150 million years back and areextinct now.
Crocodile
Snake
Chameleon
Tortoise
Tyranosaurus
Fig 1.15 - Some examples of reptiles
Poikilothermic animals (coldblooded animals)
These are animals in which thebody temperature keeps changingaccording to changes in thesurrounding environment.
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Digestive system consists of mouth, pharynx, oesophagus, stomach, smallntestine, large intestine and associated glands.
Respiration takes place through lungs.
The heart is three chambered. The heart is more evolved than inAmphibians. Reptiles are also cold blooded animals.
Nervous system consists of a brain a spinal cord and 12 pairs of cranialnerves.
Reptiles are unisexual animals. They reproduce by sexual methods. Alleptiles are egg laying (oviparous) animals. Ex : Chameleon, Snake, Tortoise,
Crocodile, House lizard etc.
1.64 AVES
Members of this class are commonly called
birds. They are found in different habitats likewater and land.
The body is covered by feathers. Feathersare diversified with various colours. They performvarious functions like protection, help in maintainingbody temperature and loss of water. Feathersalso help in sexual attraction. In birds, forelimbsare modified into wings which help in flight.Depending upon the habitats of different birdshindlimbs are variously adapted for runningwalking, swimming and wading.
The body is very light and the bird can flywithout friction. The bones are hollow, light andilled with air. Such bones are called pneumaticbones.
Meaning of aves
In Latin - Avis - Birds
The smallest bird
Humming bird is the smallest birdwhen it is developed completely, itweighs about 3 grams! It can alsofly backwards!
The biggest bird
The male Ostrich grows about 2.4meters in height and weighs about
140 kgs. It can run at a speed of60 kms per hour.
Warm blooded animals
(Homeothermic)
The animals which do not fluctuatetheir body temperature with changesin the environmental temperatureare called homeothermic animals.In these animals body temperature
remains contant.
Fig 1.16 - External features of a bird
Migration in birds
Arctic tern, a nonstop migratorybird can travel to a distance of18,000 kms.
Syrinx-the Voice Box
The voice box which has vocalcords is streched across and
responsible for the production ofSound.
Wing feather
Leg
Eye
Wing
BeakTail feathers
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Lungs are specialized for storing excess air. The voice box or syrinx isound at the base of trachea.
A four chambered heart is present. Birds are active warm blooded
homeothermic) animals. Heart beat is very rapid than other animals.
Nervous system is more evolved than in reptiles. 12 pairs of cranial nerves
are found.
Birds are unisexual, reproduce by sexual methods. All are oviparous andeggs are covered by calcarious shells.
Ex : Ostrich, Parrot, Hawk, Pigeon, Penguin, Flamingo, Arctic tern etc.
1.65 MAMMALIA
Members of this class are commonly called
Mammals. The animals bear mammary glands toeed their young ones.
Heart beat in birds
The rate of heart beat and sizeof the heart in birds varies with
the size and activities of birds.In Turkey heart beat may beless than 100 per minute.
In hens, the rate of heart beatmay be 300 per minutes. Insparrow it may be 500 perminute. In some smallestspecies of birds, it may be upto
1,500 beats per minute.
Meaning of mammalia
In Latin, - Mamma = Breast
The animals having mammaryglands
Peacock
King fisher
Kiwi
PenguinGray horn Bill
Tern
Pelican
Flemingo
Myna
Ostrich
Fig 1.17 - Common examples of Birds
Kiwi
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These are the most evolved animals in theanimal kingdom. The skin is covered by hairs
Mouth is provided with jaws bearing teeth. The
eyes have movable eyelids and eyelashes. Ear has aleshy external pinna. Limbs are pentadactyl, endingn claws or nails.
Smallest mammal
‘Pigmy Shrew’ is the smallest
mammal weighing only about 2.5grams
Biggest Mammal
The Blue Whale is the largest knownaquatic mammal. It is nearly 30 meterslong, 200 Metric tons in Weight.
An architect of the animalworld
The mammal called Beaver isan excellent architect of theanimal world. An illustrationobtained about the intelligence
of these animals is that theyconstruct dams near theirshelter. They make use ofstones and tree trunks andconstruct dams along the pits
near their shelter and they evenconstruct reservoirs!
ForelimbHind limb
Mouth
Eye
Hairy Skin
Tail
Fig 1.18 - External features of a typical mammal - rat
Ear
Kangaroo is the native mammal of
Australia. It has a pouch(massupium) formed by a fold skin
on the lower part of body below thestomach. The young ones are rearedin this pouch.
Bat
Giraffe
Elephant
Panda
Lion
Kangaroo
Platypus
Echidna
Whale
Fig 1.19 - Some common examples of mammals
The mammal sloth walks and
sleeps upside down
Viviparous animals
Animals giving birth to young onesare called Viviparous animals
Egg laying mammals
The duck-billed Platypus, the spinyant eater Echidna are the only twoegg laying mammals.
Bat is mammal capable of trueflight.
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Respiration takes place through lungs. The thoracic and abdominal cavitiesare separated by a muscular membrane called the ‘diaphragm ’
The heart is four chambered with two auricles and two ventricles.
The nervous system is more evolved than other vertebrates. It consistsof brain, spinal cord, cranial and spinal nerves.
Mammals are unisexual animals. Reproduce by sexual methods. Mostmammals give birth to young ones except echidna and platypus. They are eggaying mammals.
Ex : Kangaroo, Whale, Bat, Giraffe, Lion, Elephant, Man etc.
After studying this unit you will ................
. recognise the important characteristics of various groups of non-vascularand vascular plants and also various groups of vertebrates.
2. cite examples for the important groups of non-vascular and vascular plantsand also for the 5 classes of vertebrates.
3. compare the characteristic features of lower plants with that of higher plants.
4. recognise the increase in complexity in the body structure from lower groupto higher groups of vertebrates.
5. appreciate the diversity among the animal groups.
Activities
. Try to visit plant nurseries, botanical gardens, zoos, natural history
museums, protected forests to note the natural habitats of flora and fauna,characteristic features of organisms both in natural and aritifcial conditions.
2. Prepare an album of pictures and photographs of various groups of plantsand animals, collected from sources like magazines, journals, specialcoverages in newspapers.
3. Join a planned field trip under the guidance of your teachers and try tocollect specimens for display in science room/laboratory.
EXERCISES. Choose the correct answer from the following
1. The brown alga among the following is .....................
a) Polysiphonia b) Sargassum c) Spirogyra d) Ulothrix
2. The multicellular cone like structures are found in ..................
a) Gymnosperms b) Bryophytes c) Pteridophytes d) Algae.
3. Two chambered heart is found in .................
a) Pisces b) Reptiles c) Amphibians d) Aves
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4. The number of chambers in the heart of birds are ................
a) Four b) Two c) Three d) One
5. An egg laying mammal among the following is ...............
a) Bat b) Giraffe c) Platypus d) Kangaroo
I. Answer the following questions :1. Mention any two salient features of multicellular algae
2. List any two important characteristics of bryophytes.
3. Differentiate between a gametophyte and a sporophyte.
4. Why are pteridophytes called tracheophytes?
5. List any two important characteristics of gymnosperms
6. List any two characteristics of angiosperms?
7. What is an inflorescence?8. Mention any two general features of vertebrates.
9. What are amphibians? Give an example.
10. What is external fertilization?
11. In which animals do you find metamorphosis?
12. Mention any two salient features of reptiles?
13. List out any two salient features of birds?
14. Mention any two salient features of mammals?15. What is prothollus?
16. What are cones?
17. What are pneumatic bones?
II. 1. Draw a neat labelled diagram of a fish.
2. Draw a neat diagram of ulothrix cell and label the following parts.
a) Cell wall b) Nucleus c) Cytoplasm d) Chloroplast
3. Draw a labelled diagrams of taproot and fibrous root systems.
V. Match the following
A B
1. Pisces a. Tortoise
2. Ambhibian b. Platypus
3. Reptile c. Sea horse
4. Aves d. Ichthyophis
5. Mammal e. Arctic tern