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1BIOLOGYDear children, given above is a beautiful picture of a house with agarden in front. But you will be surprised to know that there are tenanimals hidden in it. Shall we find them?The picture shows a good relationship between plants and animalsin a non-living environment.100
ECO SYSTEM1.1. Eco System“Wild elephants stray into humanhabitation near Hosur”On 24th March, 2010, wild elephants entered Kumudepalli village, inKrishnagiri District.They were driven into the Sanamavu Forest near Hosuron that day. Three male wild elephants strayed into human habitation nearHosur on Tuesday.According to the forest officials, the elephants aged between fifteen andtwenty strayed into Kumudepalli village in the morning. On information, theofficials led by District Forest Officer V.Ganesan, Assistant Conservatorof Forest K.Rajendran and Hosur Ranger R.Madheswaran drove thepachyderms to the nearby Sanamavu Reserve Forests with the help of thevillagers by bursting crackers.Wild elephants entering into the human habitations have become anorder of the day for the past three to five months. They did not harm anybodyduring the operation. Of the three elephants one is sub male elephant withthe age of fifteen. And the other two are about twenty, an official said.The above information is a newspaper report. Why do these elephants havecome out of the forest? What has disturbed them?Elephants live in forests. Forest is an ecosystem. Forests are the naturalhabitats of elephants. People have been cutting down trees and reducing forestcover for cultivation and other purposes. The elephants lose their habitations inthe reduced forest area. So they are forced to come out of their forest homes(ecosystems) and move in the areas where people live.101
1BIOLOGYEcosystemBiotic ComponentsPlantsAnimalsAbiotic ComponentsSoilAirA community of organisms livingtogether with its non-living environmentconstitutes an eco-system.2. Consumers: They are animalswhich depend on plants andanimals for their food. eg. Goat.3. Decomposers: They are organismswhich feed upon dead matter to getenergy and bring back the nutrientsto the soil. eg. bacteria and fungi.Components of Eco-systemBiotic ComponentsThe living components are broadlyclassified into three categories.Sunlight1. P roducers: They are greenplants that prepare theirown food by the process ofphotosynthesis.Eco-systems may be natural orartificial. A pond, a grassland, a forest,a lake, a desert etc. are examples ofnatural eco-systems. An aquarium, apark, a paddy field, etc. are examplesof artificial eco-systems.An eco-system consists of two maincomponents. They are biotic (living)and abiotic (non-living) components.WaterAbiotic ComponentsThese include the soil, water, air andclimatic factors such as temperature,sunlight, humidity etc.102
ECO SYSTEMActivity - 1.1I do(( I observe the picture.(( I suggest three biotic and two abiotic factors in it.(( I write the names of three birds.1.2.3.1.2. FOOD CHAINThe sun is the ultimate source of energy to all living things. Green plants capturesolar energy and convert carbon-dioxide and water into food by photosynthesis.This food energy is transferred to the primary consumer when they eat plants.Then the primary consumer is eaten by the secondary consumer which in turnis eaten by a tertiary consumer. So, in a given ecosystem, there is a processof organisms eating some others or being eaten by some other organisms. Thepath of energy transfer from one organism to another in a single direction iscalled a food chain.1. Food chain in a grasslandPaddy(Producer)Mouse(Herbivore )Snake(Carnivore)103Eagle(Top Carnivore)
1BIOLOGY2. Food chain in a e)3. Food chain in a pondPhytoplanktonInsectSmall fishTop Carnivore(Eagle)FourthTrophic LevelCarnivore(Snake)ThirdTrophic LevelHerbivore(Mouse)SecondTrophic LevelProducer(Plants)Large fishManIn a food chain, each group oforganisms occupies a particularposition. The position of organisms ina food chain is called trophic level.The first trophic level is ofproducers. The second trophic level isof herbivores. The third trophic level isof carnivores. The fourth trophic levelis of top carnivores.MORE TO KNOWIf one link in a food chain is brokenit would result in the extinction of aspecies.FirstTrophic Level104
ECO SYSTEM1.3. FOOD WEBActivity 1.2I do(( I find which trophic level I belong to when I eat vegetables or meat.(( With dotted lines I show few more links to ctpaddyinsectFood WebIn a given ecosystem, a single food chain may not exist separately. An animalcan eat more than one kind of food. For eg. an eagle can eat a rabbit, a mouseor a snake and a snake can feed on a mouse or a frog. So, many food chainsget interlinked.A network of interlinked food chains is called a food web.1.4. FLOW OF ENERGYThe sun is the ultimate source of energy for all living things. At first, the solarenergy flows from the sun to the surface of the earth. Green plants trap the solarenergy and convert it into chemical energy (food).The amount of energy decreases from one trophic level to another. The flowof energy is always in one direction only.105
1BIOLOGY1.5. BIOMEWe know that all organisms acquire energy from the sun directly or indirectly.But, does the sun have any other effect on us? Yes. The rotation of the eartharound the sun has an effect on the climate of a place. You have already studiedabout ecosystem. An ecosystem may be small or big. When small ecosystemsare put together, they form a vast geographical area which supports a widevariety of flora and fauna. At the same time such a vast area has a different type ofclimate. Such a vast geographical area is called biome.TundraTaigaDesertTropical rain forestDeciduous forestTemperate grasslandsavannaMountainsTHE DIFFERENT BIOMESWe can view our earth as variousbiomes based on their climate and alsothe latitude and longitude on which theyare present. Based on the types of floraand fauna, the biomes are classified intomany types.1.5.1. Types of forest1) Tropical Rain Forest: They arefound in South America, Africa and IndoMalaysia region near the equator. Theweather is warm (20oC-25oC). Rainfall isplentiful, 190 cm per year. In India, theyFig. 1.1. Tropical Rain ForestActivity 1.3we doDivide the class into groups of four or five students each. Each group hasto select any Biome and discuss its climate, flora and fauna found there.106
ECO SYSTEMin Punjab, Tamil Nadu, Uttar Pradesh,Bihar, Odisha and Madhya Pradesh.are found in Andaman and NicobarIslands, Western ghats, Assam andWest Bengal.6) Taiga: It is found in Canada,Europe and Russia. They are alsocalled Boreal Forests. The climate isof a short cool summer and a longwinter with abundant snowfall. Theannual rainfall is 20cm to 60 cm. Mostof it is covered with snow and ice. Itis found in Himachal Pradesh, Punjaband Kashmir in India.2) Savannah: They are found inSouth Africa, Western Australia, NorthWest India and Eastern Pakistan.They love a dry weather alternatingwith wet weather. The rainfall is about25cm per year. Frequent fires occurduring the dry season. In India, grassyplains are found in the Nilgiris, Khasihills and Naga hills.7) Tundra: It is found in south ofthe ice covered poles in the Northernhemisphere. Though it receives 25 cmof rainfall, it has permanently frozen soil.The climate is extremely cold and windy.The temperature is less than 10oC. InIndia, it is found in the Himalayas.3) Deserts: They are found in Africa,Arizona in America and Mexicandesert in Mexico. The days are hot andnights are cold. The annual rainfall isless than 25 cm. In India, it is found inRajasthan (The Thar Desert).1.5.2. Importance ofForests1. Forests are the sources for theformation of rivers.2. They increase the rainfall.3. They prevent soil erosion and floods.4. They become habitats to animals.Fig. 1.2. Desert4) Temperate Grassland: It is foundin North and South America and partsof Europe. The annual rainfall is 25cmto 100 cm. They have two very severedry seasons. They have windy hotsummers and cold winters. In India, Itis found in Uttar Pradesh.5. They maintain the oxygen andcarbon dioxide balance in nature.Forests are considered as God’sfirst temples. They play an importantrole in our day-to-day life.5) Deciduous Forests: They arefound in North America, Eastern Asiaand Europe. They receive 75 to 100cm of rainfall. The climate is moderatewith mild winters. In India, it is found107MORE TO KNOWVanamahotsav is an annualIndian tree planting festivalcelebrated in the month of July.It is to create an enthusiasmin the minds of people toconserve forests.
1BIOLOGY1.5.3. DIFFERENT FLORA AND FAUNABiomes have a variety of plants and animals. The flora and fauna found in onebiome is completely different from that in the other biome due to the differentclimatic conditions. The kind of flora and fauna found in different biomes aregiven below: India is one of the 12 mega biodiversity centres in the world withimmense flora and fauna.S.NOBIOME1.TropicalRain ForestFLORAFAUNALofty trees like teak,rubber, lianas, epiphytes,orchids, fernsherbivores,insectsrodents,monkeys, bats, birds, large cats,snakesSavannahGrassesbirds, kangaroos, lions, zebras,giraffes, cheetahs, elephants,termites3.DesertSucculent plantslike cactus, acacia,calotropis, datepalm sslandPerennial grasseswolves.bisons,antelopes. insects etc5.DeciduousforestOak, maple, mosses,acacia, pine, firsquirrels, black bears, beetles,birds, small mammals6.TaigaSpruce, fir, pine, aspen,birch,willows, mosses,lichens, fungiporcupines, red squirrels, hares,grey wolves, insects etc7.TundraSedge, broad leafedherbs, lichens2.Activity - 1.4I match the product with its ffee5.MedicineVeena6.DrinkPalm Leaves108coyotes,reindeers, owls, foxes, wolves,migratory birds, polar bears,penguinsi doActivity - 1.5i doPrepare a posteror logo or slogan ora notice related todeforestation.
ECO SYSTEMevaluation1. Pick out the correct answer:a) Forest is an area with high density of (trees / grass)b) is an example of a natural ecosystem. (Paddy field / Desert)c) The third trophic level in a food chain is called(herbivore / carnivore)d) A network of interlinked food chain is called a(food web / food cycle)e) The festival of “Vanamahotsav” is celebrated in the month of .(June / July)2. Rearrange the following words to form a food chain.(a) snake, mouse, paddy, eagle, grasshopper. (b) man, big fish, phytoplankton, small fish, insects.---------- ----------------- ------------- ------------- ----------3.Third Trophic levelHerbivorePlantsCarnivoreSecond Trophic levelProducersSnakeMouseFirst Trophic levela) Suggest the common idea derived from these boxes.b) Make two logical pairs using the datac) Analyse the data given above and make a food chain.4. Differentiate between the following:a) Consumers and decomposersb) Food chain and food web5. Discuss the effects of deforestation on the following:a)Wild animalsb)Environment109
1BIOLOGY6. Food web in a forest is given below:Top carnivore :Carnivore :Herbivore:SnailsProducers:HawkCrowWood LiceFallen leavesOwlWormsLiving LeavesRatsMice SquirrelsGrassesSeedsa) From the diagram identify an example of each of the following :i) a Carnivoreii) a Herbivoreiii) a Producerb) Draw as many as food chains of four organisms selected from the food web.7. Match the following types of forests with their unique characteristic features.Rain forest, Savannah, Desert, Grassland, Taiga, Tundra.S.No.Characteristic featureTypes of Foresta.Frequent forest fireb.Windy weatherc.Snow and iced.Hot days and cold nightse.Ice covered frozen soilf.Plentiful rainfall110
ECO SYSTEM8. Given below are a list of animals. Match it with the biome where they arefound.a) Snake-Savannahb) Cheetah-Tundrac) Camel-Tropical Rain Forestd) Antelope-Taigae) Black bear-Desertf) Grey wolf-Deciduous forestg) Penguin-GrasslandFURTHER REFERENCEBooksEcology - Shukla and Chandel, S.Chand & Company, New DelhiEnvironmental Science (9th edition) - Enger and Smith, McGrawHill, New YorkWebsiteswww.national geographic.comwww.mongabay.comPlaces of scientific importance for visit1.Coral reefs in Mandapam, Ramanathapuram District2.Mangrove forest in Pitchavaram, Cuddalore District111
WATER - A PRECIOUS RESOURCEFig. 2.1. Mettur damValli, Inba and Selva have gone on a picnic to Mettur dam. Valli is surprisedto see so much of water available on our planet Earth. She wonders why we stillexperience shortage of water. Selva tells them that 70% of our Earth is made ofwater but only 3% of it is fresh water. Hence only a fraction of it is fit for humanconsumption.Children, shall we find out why wecelebrate March 22 every year asWorld Water Day.It is to arouse an awareness113
2BIOLOGY2.1 AVAILABILITY OF WATERMORE TO KNOWWater is a natural resource thatis vital for both plants and animals.Water exists in abundance on ourplanet Earth. However, only a verysmall fraction of it is fit for humanconsumption.IMPORTANT DAYSWorld Wetland Day - Feb 2World Forest Day - March 21Earth Day - April 22Most of the water that exists on theearth is found in the seas and oceans.Sea water and ocean water are highlysalty and hence unfit for drinking. Mostof the fresh water is frozen glaciersas in the polar regions and thus notreadily available.World Environment Day- June 5Natural Resources Day - October 5Nature Conservation Day - Nov 25Activity 2.1i doIcollectclippingsfromnewspapers and magazineson the news items, articlesand pictures related to watershortage. I paste them in myscrapbook. I show and share theinformation with my teachers andfriends.The United Nations states that “theamount of water for drinking, washing,cooking and maintaining properhygiene is a minimum of 50 litres perperson per day”. This amount is abouttwo and a half buckets of water for aperson for a day.Others 0.6%Surface water 0.3%Freshwater 3%30.1%Ground waterRiver 2%Swamp 11%69%Glaciers &Ice capSaline water 97%Lakes 87%Fresh WaterFig. 2.2.Water on EarthFresh Surface Water114
WATER - A PRECIOUS RESOURCE2.2. SOURCES OF WATER3. River waterThe water in the rivers is obtainedeither from rainfall or melting of snow(glaciers) on the mountains.1. Rain waterRain water is the purest form ofwater. Pure water evaporates undersunlight from the seas and riversleaving behind the impurities. It rainsdue to the precipitation (condensation)of tiny water droplets present in theclouds. The first showers dissolvecertain gases present in air and bringdown them along with the suspendedimpurities.Subsequentshowerscontain only pure water.4. Sea and Ocean waterOcean is a large body of water.Million litres of water is present inocean. But the water is salty and isnot fit for any domestic or agriculturaluse.5. Lake and Pond waterLakes are inland depressions thathold standing fresh water almostall the year round. Ponds are small,temporary or permanent bodies ofshallow water. They are still a minorcomponent of the total world watersupply.Fig. 2.3. Rain Water2. Glaciers, ice and snowOf the 3 percent of fresh water thatis fresh, about three – fourths are tiedup in glaciers, ice caps and snowfields.They occur only at high altitudes orhigh latitudes.Activity 2.2Fig. 2.4. Glacierswe doCollect samples of rainwater, water from hailstones, river water, sea water andlake or pond water.S.No.SamplePurity1.2.3.4.5.115ColourUses
2BIOLOGY2.3. FORMS OF WATERWe already know that water exists in three states i.e., solid, liquid and gas.All the three states are reversible or interchangeable.All the three states of water are also present in our natural environment atany given time.GasSolidFig. 2.5. (a) Waterfreezes to ice at 00CLiquidFig. 2.5. (b) Water remains a liquid between00C and 1000Cform of water droplets. Also liquid water covers three quarters of the surface of the earth in the form of lakes,rivers and oceans.1. Solid: Ice is the solid form of water.It can be found in the atmosphere in theform of ice crystals, snow, ice pellets,hail and frost. It is also found in thepolar regions and on high mountainpeaks.3. Gas : Water vapour is the gaseousform of water and exists as mist, fog,steam and clouds.2. Liquid: Rain and dew are in theCondensationFig. 2.5. (c) Waterchanges to steam at1000CPrecipitationCondensation(clouds form)TranspirationSurface runoffEvaporationAccumulationThe continuous circulation of waterin nature is called water cycle. It is alsocalled the hydrological cycleFig. 2.6. Water cycle116
WATER - A PRECIOUS RESOURCE2.4. GROUND WATERCloudsTranspiration from plantsWater tableStreamAquiferFig. 2.7. Underground Water or Aquifer(( P recipitation in the form of rain orsnow provides fresh water to ourearth.(( M ost of the fresh water returns to theoceans through rivers.(( A small portion of rain water seepsinto the soil and is stored asunderground water.(( U nderground water is also called anaquifer.MORE TO KNOWA World Bank reportsays, “India is the largestuser of groundwaterin the world and itsundergroundaquifersare being depleted at analarming rate”.(( T he top level of this undergroundwater is called the water table. If wedig a hole in the ground near a waterbody we find that the soil is moistthere.(( T he moisture in the soil indicates thepresence of underground water.(( I f we dig deeper and deeper, wewould reach a level where all thespace between the particles of soiland the gaps between rocks arefilled with water. The upper limit ofthis layer is called the water table.(( T he water table varies from place toplace and it may even change at agiven place.(( W ater in the aquifers can usually bepumped out with the help of tubewells or hand pumps.117
2BIOLOGY2.5. DEPLETION OF WATER1. Natural forcesScanty rainfall and hot winds arenatural forces that may deplete thewater table.2. Human causesDeforestation, increased population,rapid urbanization, overgrazing by cattle, excess tapping of ground water arehuman causes.3. Salt water intrusionMany parts of the world are losingfreshwater sources due to saltwaterintrusion. Over use of undergroundfreshwater reservoirs often allows saltwater to intrude into aquifers andaffect the water table.4. Commercialization of waterresourcesSome of the private companiessuck a large quantity of water fromrivers and underground aquifers.5. Sand grabbing from riversSome rivers are deeply affected bysand grabbing. eg. Palar riverFig.2.8. Deforestationgeneral, the northern half of the countryis subjected to extremes of rainfall.India has a large network of rivers too.The three major rivers the Indus, theGanga and the Brahmaputra originatein the Himalayas and drain nearly twothirds of the land area.During the monsoon, water level inrivers increase greatly that some timesit may result in floods. On the otherhand, during the dry season, waterlevel goes down quite a bit in most ofthe large rivers. Smaller tributaries andstreams generally dry up completely.To regulate water flow in these riversand to distribute water more evenlythroughout the year, large dams havebeen built across a number of rivers.MORE TO KNOW2.6. DISTRIBUTION OF WATERWater availability in India dependsgreatly on the seasonal monsoons.The monsoons bring heavy rains overmost of the country between Juneand September. Except Tamil Nadu,which receives over half of its rainin October and November. India hasplaces of dry condition of deserts.(Thar desert) and places with rainforestclimate (North Eastern States) too. In118(( India receives nearly 4 per cent ofthe global precipitation and ranks133 in the world in terms of wateravailability per person per annum.(( The total renewable water resourcesof India is estimated at 1,897 sq kmper annum.(( By 2025, it is predicted that largeparts of India will join countriesor regions having absolute waterscarcity.
WATER - A PRECIOUS RESOURCEActivity 2.3WE DOGiven here is the rainfall map of India. It gives theaverage annual rainfall in different regions of ourcountry.1. We locate on the map the place we live in.2. Are we blessed with sufficient rainfall?3. We discus about the necessary steps to be taken toincrease the rate of rain fall.2.7. SCARCITY OF WATERScarcity of water is defined as asituation where there is insufficientwater to satisfy normal requirements.Though water is a renewableresource, we, the humans, are usingit at a faster rate than it is beingreplenished.There are various factorscontributing to the depletion ofwater table.(( U ncontrolleduseofborewell technology for extractinggroundwater.(( P ollution of freshwater resources.This is due to the flow of untreatedsewage from homes, toxicchemicals from industries and ofpesticides and insecticides usedby farmers into water bodies(( N o effective measures for waterconservation.(( G rowing population has resultedin a growing demand for houses,offices, shops, roads etc. As aresult, open areas like parksand playgrounds are used forconstruction of buildings. Thisreduces the seepage of water intothe ground.(( G rowing population has alsoresulted in an increase in thenumber of industries. Water isused in almost every stage ofproduction of things that we use.(( A s we already know India is anagricultural country and farmershave to depend on rains forirrigating their fields. However,erratic monsoons result in excessuse of groundwater therebydecreasing the undergroundwater.Fig. 2.9. Water is vital for the survivalof all organisms on earthMORE TO KNOWA design of a toilet in which humanexcreta are treated by earthworms hasbeen tested in India. It has been foundto be a novel technique. Toilets thatrequired little water is safe for processingof human waste. The conversion oftoilet waste is very simple and hygienic.The human excreta are completelyconverted to vermicakes – a resourcemuch needed for soil.119
2BIOLOGY2.8 WATER MANAGEMENT - RAINWATER HARVESTINGThe activity of collecting rainwaterdirectly or recharging it into the groundto improve ground water storage in theaquifer is called rain water harvesting.To recharge the groundwater, rainwaterthat falls on the terrace of the buildingsand in the open space around thebuildings may be harvested. Rooftop rain water can be diverted to theexisting open / bore well. Rainwateravailable in the open spaces aroundthe building may be recharged intothe ground by simple but effectivemethods. The Government of Tamilnadu leads the nation in implementingrainwater harvesting programme.It has been made mandatory for allhouses and buildings in the state toinstall rainwater harvesting facilityRain water harvesting techniquesThere are two main techniques of rain water harvesting.Collection areaRecharge facilityInletSoilSoak wayStorage TankFig. 2.10. Rainwater harvesting1. Storage of rainwater on thesurface for future use.Advantages of rainwaterharvesting(( R ainwaterharvestingcanreduce flooding in city streets.(( Sea water intrusion in coastalareas can be arrested.(( The ground water can beconserved.(( RainwaterHarvestingcanreduce top soil loss.2. Recharging the ground water.(( S urface water is inadequate tomeet our demand and we haveto depend on ground water.(( D ue to rapid urbanization,infiltration of rain water intothe sub-soil has decreaseddrastically and recharging ofground water has diminished.(( It can improve plant growth.120
WATER - A PRECIOUS RESOURCEActivity 2.4we doLet us discuss the ways in which we can conserve water under the followingheadings:1. Save a drop today. Keep drought away2. Rain drops - life giving drops.3.2.9. SCIENCE TODAY2.9.1. DRINKING ICE BERG WATERFig. 2.11.Melting of glacierIcebergs are pieces of glaciers thathave drifted into the ocean and wouldotherwise melt and become saltwater.Icebergs are mostly white becausethe ice is full of tiny air bubbles. Thebubble surfaces reflect white lightgiving the iceberg an overall whiteappearance. Ice that is bubble freehas a blue tint which is due to thesame light phenomenon that tints thesky. Drinking iceberg water is one ofthe most environmentally consciousmethods of meeting the world’sincreasing demand for clean freshwater. It is a noteworthy fact that allthe North Indian Rivers originate in theglaciers of Himalayas.There are two very positiveenvironmental impacts from the useof drinking water from icebergs:1. It decreases human dependencyon traditional watersheds suchas rivers and lakes, and thereforedecreases human impact onthese delicate and overstressedecosystems.2. It helps to reduce rising sea levels,which have been caused by polaricecap melting. Since most of theglaciers were formed thousandsof years ago from falling snow,and snow results from condensedwater vapour in the atmosphere,the water from icebergs is quitepure. Icebergs are comprised ofpure fresh water.121
2BIOLOGY2.9.2. DESALINATION OF SEA WATERDesalination is an artificial processby which saline water ( sea water) isconverted into fresh water.The most common desalinationprocesses are :1. Distillation 2. Reverse Osmosis1. DistillationThe process in which bothevaporation and condensation go sideby side is called distillation2. Reverse OsmosisThe process of forcing water underpressure through a semi permeablemembrane whose tiny pores allowwater to pass but exclude most saltsand minerals is called reverse osmosis.of Rs.48.66 per 1,000 litres. TheDesalination Plant serves potablewater to an estimated population of 5lakh in Chennai.The Nemmeli desalination plantThe State Government has decidedto alleviate the freshwater problemsby the desalination of sea water.Besides the Minjur plant, the ChennaiMetropolitan Water Supply andSewage Board (CMWSSB) is alsoconstructing a Desalination Plant atNemmeli at a total cost of Rs.908.28crore. The plant has a capacity toconvert 100 million litres per day asThe State Government of TamilNadu has taken up a venture toconvert sea water into potable waterby the Reverse Osmosis process tosolve the problem of water scarcity inChennai.The Minjur Desalination PlantIt is the largest desalination plant inIndia. It is located in Kattupalli villagenear Minjur, about 35km north ofChennai. The plant is established on a60 acre site at a cost of Rs.600 crore. Itconsists of 8,600 Sea Water ReverseOsmosis (RO) membranes to convertsea water into potable water. The ROtechnology of the plant produces 100mld (million-litres-a-day) of freshwaterfrom 273 million litres of sea water.The Minjur Desalination Plant supplies100 mld of fresh water to the ChennaiMetro Water Corporation at the rate122Fig. 2.12. The Desalination Plant atMinjur, Thiruvallur Dt.,MORE TO KNOWWater obtained through distillationis called distilled water. This wateris normally pure enough for usein school science lab and medicallaboratories.
WATER - A PRECIOUS RESOURCEpotable water from sea water. Waterfrom the Nemmeli plant would becarried over 40 km to the city, to besupplied to its residents.2.9.3. Sweet water on earth1. T he 2006Mumbai “sweet”seawaterincidentwasaphenomenon during which theresidents of Mumbai claimed thatthe water at Mahim Creek hadsuddenly turned “sweet”. MahimCreek is one of the most pollutedcreeks in India that receivesthousands of tonnes of raw sewageand industrial waste every day.2. Within few hours of the Mumbai“sweet”seawaterincident,residents of Gujarat claimed thatseawater at Teethal beach hadturned sweet as well.MORE TO KNOWFig. 2.13. Teethal Beach ( Gujarat)Geologists at the Indian Instituteof Technology in Mumbai offered theexplanation that water turning sweetis a natural phenomenon. Continuousrainfall over the preceding few dayshad caused a large pool of freshwater to accrue in an undergroundrock formation near to the coast.Then this water discharged into thesea as a large “plume”, as fracturesin the rocks widened. Because of thedifferences in density, the dischargedfresh water floated on top of the saltwater of the sea and spread alongthe coast. In course of time, the twowould mix to become normal seawater once more.Activity 2.5I doI calculate the amount of water I use daily.All oceans and seas have saltywater. The saltiest of all is the Deadsea. It is called “dead” becausethe high salinity prevents any fishor other visible aquatic organismsto live in its water. Imagine 300grams of salt in one litre of water.Interestingly, even if a person doesnot know how to swim, he wouldnot drown in this sea. He wouldonly float in it.ACTIVITYAMOUNT OF WATERUSED IN LITRESDrinkingCookingBathingWashingWater is a resource . Water isessential for the hygienic well beingof all human beings.So water mustbe used optimally .123
2BIOLOGYevaluation1. Pick out the correct answer.a. Water exists in abundance on the planet -------------- (Earth/ Mars).b. ---------------- are a huge store of water. (Oceans / Ponds)c. ---------------- is the gaseous form of water. (Rain / Water vapour)d. Desalination is an artificial process by which -------------- is converted to freshwater. (sea water / river water)2. Given below are some sources of water. Arrange the jumbled words in the rightorder and fill in the blanksINARRAINOWNSRRVIEASE .AKELNOPD3. The diagram of a water cycle is given. Fix the following words in the right place;sea, cloud, evaporation, rain4. Why is supply of water essential to humans?5. a) Why has urbanisation occurred ? List the ways in which urbanisationi) benefits humanii) harmful to wild life.b) Suggest one way in which the effects of urbanisation can be reduced.6. Advise class leaders on water conservation in your school.You can give them thefollowing instructions;a) Close the water tap after use.e)b)f)c)g)d)h)124
WATER - A PRECIOUS RESOURCE7. All of us use water every day. Fill in the table according to your observation:S.No.IN SCHOOL1.Source of water2.Number of taps3.Taps that leak4.Water wasted by leakageevery day
The flora and fauna found in one biome is completely different from that in the other biome due to the different climatic conditions. The kind of flora and fauna found in different biomes are given below: India is one of the 12 mega biodiversity centres in the world with immense flora and fauna. S.nO biOME FlOra Fauna 1. Tropical Rain Forest
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This textbook on Nutrition and Dietetics includes content on Food Science and Nutrition at plus one level, while at plus two . Gopalan. C, Rama Sastri B.V. and Balasubramanian S.C., 1989, Nutritive Value of Indian
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3 CLEFS The clef, a symbol that sits at the leftmost side of the staff, specifies which lines and spaces belong to which notes. In a sense, the clef calibrates or orients the staff to specific notes. The three most common clefs are: The Treble clef for high range notes The Bass clef for low range notes The Alto clef for middle range notes The Treble clef (also called the G Clef because it .
