Natural Resources | NCERT Class 9 Science Ch 14

Table of Contents

Notes Natural Resources

In-Text Questions & Answers - Class 9 Science - Natural Resources

Exercises Questions & Answers - Natural Resources - NCERT Class 9

NCERT Class 9 Science Chapter 14 | Natural Resources | In-Text Questions & Answers | Exercises Questions & Answers | Notes & pdf

Q1. What is biosphere?

Till now, as per our knowledge, life only exists in our planet i.e. Earth. Earth has life-supporting natural resources i.e. the land, the water and the air. Lithosphere is the outer crust of the earth. Hydrosphere is the water which is 75% of our earth’s surface. Water also exists in underground. Atmosphere is the air which gives a covering to our earth like blanket. Biosphere is the totality of aforesaid resources i.e. lithosphere, hydrosphere and atmosphere. These resources form a life-supporting zone by interacting with each other and make life possible. Also we may divide biosphere into two components. These are A. biotic component i.e. living things, and B. non-living or abiotic component i.e. the land, the water and the air.

Q2. How is our atmosphere different from the atmospheres on Venus and Mars?

Earth has a blanket covering of air which is a mixture of various gases like nitrogen (N₂), oxygen (O₂), argon (Ar), carbon dioxide (CO₂), water vapour and other gases. The air plays life supporting role in Earth. Quantity of carbon dioxide (CO₂) in air is just a mere fraction of a percentage (0.04 % approximately).

On the other side, atmosphere in Venus and Mars has major component in the form of carbon dioxide (CO₂) which constitutes 95 to 97 % of atmosphere. Due to excessive presence of carbon dioxide (CO₂), no life exists in Venus and Mars.

Q3. How does the atmosphere act as a blanket?

The most important property which helps air to function as blanket is conductivity of heat. Basically air is bad conductor of heat. This property of air keeps the average temperature of the Earth not only during the day but also during the course of whole year. Air prevents the abrupt and sudden rise of temperature during daylight hours and retards the escape of heat into outer space during night. Thus air gives a blanket-like covering to the Earth and maintains ambient temperature for living organisms. Also atmosphere contains ozone in the upper layer which protects life from harmful ultraviolet radiation. Despite being equidistant from the Sun, the Earth has atmosphere but the Moon has no atmosphere. Due to absence of the atmosphere, the Moon faces temperature variation ranges from -190^oC to 110^oC.

Q4. How quantity of carbon dioxide in natural resources or atmosphere remains balanced?

Air is a mixture of various gases like nitrogen (78%), oxygen (20%)argon (0.93%), carbon dioxide (0.04%), water vapour and other gases. Oxygen, required by eukaryotic cells and many prokaryotic cells, helps to break down glucose molecules and get energy for their activities. But this action also produces carbon dioxide. Combustion is another process where oxygen is consumed and simultaneously carbon dioxide is produced. That combustion may take place in home, factory, forest fire etc.

Though there are lots of other process through which carbon dioxide mixes in air, but it’s quantity remains a mere fraction of a percent in air. Because carbon dioxide is balanced mainly in two ways. Firstly, green plants convert carbon dioxide into glucose in the presence of Sunlight. We term this process as photosynthesis. Secondly, many marine organisms make their shell like structure using carbonates dissolved in salt water.

Q5. What causes winds?

The uneven heating of the atmosphere in different regions of the Earth causes winds. The energy from the Sun starts heating the land and the water during daytime. The land and the water bodies and seas radiate and reflect some heat which helps the atmosphere to be heated. Thus air becomes heated and it rises up. As land gets heated faster than water, so air over land gets heated faster than air over water bodies and seas. Thus air over land rises up after heating and creates a region of low pressure over land. Then air over water bodies or seas moves into the region of low pressure over land. Thus convection currents are set up in the air and air moves from one region to another region. This movement of air creates winds.

Similarly, at night land cools down faster than sea. So air over sea stays warmer than land and it rises up and creates a region of low pressure. It causes movement of air from land to sea. What we discussed so far is general and simplistic reason of winds. Because other factors influence winds such as rotation of the Earth, the presence of mountain ranges etc.

Q6. How are clouds formed?

During the daylight hours water bodies get heated. It causes evaporation of a large amount of water which mixes into the air. Some other biological activities also cause mixing of water vapour into the air. Simultaneously air also get heated and rises up carrying water vapour with it. As soon as the hot air rises up, it expands, cools and causes water vapour to condense in the form of tiny droplets. Especially dust and suspended particles present in the air accelerates condensation of air into water droplets. Thus they play the role like a nucleus in the formation of droplets. These droplets further condense more and grow bigger. As a result it becomes heavy, big and turns into cloud.

When the clouds get heavier, it falls down in the form of rain. Sometimes lower temperature causes precipitation in the form of snow, sleet or hail. The south-west and north-east monsoon bring rains most areas in India. Mawsynrum, a town in northeastern India is the place of highest rainfall in India. India Meteorological Department forecasts weather report in India. The advancement in satellite technology help weather department to predict even more accurate nowadays like forecasting of depression and cyclone.

Q7. What causes air pollution?

We know that air is a mixture of various gases like nitrogen, oxygen, argon, carbon dioxide etc. The main cause of air pollution is the combustion of fossil fuels like coal, petroleum etc. That fuels contain small amount of nitrogen and sulphur. The combustion of fossil fuel produces different types of oxides of nitrogen and sulphur which are dangerous for our health. These oxides mix with air and enter our body through breathing. Said oxides also dissolve in rain to give rise to acid rain.

The fossil fuel also results unburnt carbon particles or substances called hydrocarbons. These suspended particles lowers visibility especially in cold weather during condensation of water in air. Generally we term it as smog and it is a clear indication of air pollution. Breathing in polluted air regularly increases our health risk. Also it may cause allergies, heart disease and even cancer.

Q8. What is AQI (Air Quality Index)? How it presents air pollution level?

Every year especially in winter Indian media raises a hue and cry about air pollution of Delhi and other metro cities. They use a term AQI to represent the severity of air pollution. AQI stands for Air Quality Index. Air Quality Index is a easily understandable tool to people to know air quality status. AQI generally expresses complex air quality data of various pollutants into a single number or index value, nomenclature and colour.

There are six AQI categories i.e. good, satisfactory, moderately polluted, poor, very poor, and severe. Concentration values of eight air pollutants (PM₁₀, PM_2.5, NO₂, SO₂, CO, O₃, NH₃, and Pb) and their likely health impacts (known as health breakpoints) decide those AQI categories.

Central Pollution Control Board of Govt. of India enables National Air Quality Monitoring Programme (NAMP) covering 344 cities and towns in the country. CPCB publishes AQI of cities based on the measured concentrations of the pollutants.

AQI table is given in the following for generalisation ⇒

Category (AQI)	AQI	Health Breakpoints
Good	0 - 50	Generally health impact is minimal
Satisfactory	51-100	People may feel minor breathing discomfort
Moderate	101-200	People suffering from lungs disease, asthma and heart diseases may feel breathing discomfort.
Poor	201-300	Prolonged exposure to this kind of atmosphere generally causes breathing discomfort to most people
Very Poor	301-400	Prolonged exposure to this kind of air generally causes respiratory problems and illness
Severe	401-500	Generally it affects healthy people and impacts seriously those people who are suffering from diseases

Q9. Why water is so essential for life-forms?

Organisms require water for their survival as all cellular processes take place in a water medium. Also all the reactions within the cells and our body take place between substances that are dissolved in water. Also transportation of substances from one part to another part of our body occurs in a dissolved form. So life-forms need to balance the level of water within their bodies in order to stay alive. Terrestrial organisms can not tolerate high concentration of salts dissolved in saline water and they require fresh water to survive.

Q10. Which sources give fresh water?

Our Earth’s surface has 75% water and 25% land. The seas and oceans house most of the water on Earth’s surface. But this water is saline and we can not drink it. We need fresh water to drink. Naturally the available sources of fresh water are rivers, ponds, lakes, snow covered mountains and ice-caps at two poles. Also some amount of fresh water exists underground.

Q11. How does water pollution affect organisms?

Water pollution happens through various ways and it affects living organism both directly and indirectly. One of the main source of water pollution is the fertilizers and pesticides. Nowadays these are extensively used in agricultural activities. Some portion of these substances get washed and dissolved into water bodies. In addition, sewage from municipalities and cities gets dumped into rivers and lakes. Waste especially chemical waste from factories is another water polluting material. This contaminated water affects living organisms including us and also causes various diseases as well as water borne diseases (e.g. cholera, diarrhoea).

Organisms that live in water are habituated to a certain range of variation in temperature. Sudden change in this temperature affects the aquatic organisms heavily. Especially it affects eggs and larvae of the aquatic organisms. Thus it affects the breeding of the aquatic organisms.

Water dissolves oxygen which is used by the aquatic organisms for cellular activities. Also we get some other nutrients dissolved in water. Reduction or removal of these desirable substances from water adversely affects aquatic organisms as well as other organisms.

Q12. How soil is formed?

Soil is a mixture of various tiny particles of the rocks. The rocks in the crust of the earth break down into tiny and fine particles through various physical and chemical processes. In addition, some biological processes also contribute in breaking down of the rock. All these process take thousand s and millions of years for breaking down of the rock. Some are discussed as follows –

Uneven Heating: During daylight the rocks get heated and it expands. Same rocks cool down and contract at night. As all parts of the rocks do not expand and contract at the same rate, so some cracks are formed into rocks. This process slowly and ultimately results in breaking down of the rocks into fine particles.

Water: Firstly, water enters into the cracks of the rocks formed due to uneven heating. Later the freezing of this water widens the cracks and accelerates breaking down of the rocks. Secondly, fast flowing water often carries small and big particles downstream. It causes rubbing of rocks between them. The resultant abrasion wears down the rocks into smaller particles. Flowing water carries these particles and deposits it further down its path. That is why soil is found in places far away from its parent rocks.

Winds: Strong winds also cause erosion of the rocks and carries particles from one place to another place like water.

Organisms: Some living organisms also contribute in the formation of soil. The lichen grows on the surface of the rocks. It releases certain substances during its growth. That substances cause the rock surface to power down. Thus it causes formation a thin layer of soil. Some plants like moss also grow on the surface of rocks and accelerate further breaking up of the rocks. Sometimes roots of big trees go into cracks in the rocks and widen the cracks during its growth.

Q13. How soil affects biodiversity?

Soil is an important natural resource that influences biodiversity. It is a mixture of fine rock particles. That is why it contains various minerals. Life-forms take these minerals as nutrients. The amount of these mineral present in soil depends on rocks from which it is formed. Also the type of soil is decided by the average size of rocks found in it.

The topmost layer of soil is called the topsoil. Basically the quality of topsoil is an area influences biodiversity in that area. Apart from containing rock particles, topsoil also contains bits of decayed living organisms known as humus. It also contains various microscopic life-forms.

The presence of humus and microscopic organisms decides the soil structure or quality of soil. It makes soil porous and allows water and air to penetrate deep underground. Thus fertility of soil also improves. Apart from humus and microscopic organisms, various minerals present in soil also contribute in improving the quality of soil. Generally soil in an area having more presence of humus, organisms and minerals increases biodiversity in that area.

Q14. What causes soil pollution?

Generally we may term soil pollution as the fact of removing useful components from soil and adding undesirable substances in soil. Soil pollution badly affects living organisms in soil as well as reduces fertility. Nowadays we use good amount of fertilizers and pesticides in farming. All these fertilizers and pesticides easily mix in soil. Using these over long periods of time affects the quality of soil. These products can destroy micro-organisms that recycle nutrients in the soil. It can also kill the Earthworms which are main factor in making the rich humus. Thus fertility of soil is also reduced by all these actions.

Q15. What causes soil erosion and how to prevent it?

The soil at a particular area is created over thousands and millions of years by tiny rock particles brought from another place. Flowing water and wind are the main factors of soil erosion. Fast flowing water easily washes away topsoil and carries it from one place to another place. Flowing water may be in form of rain, flood or stream. Similarly strong wind also carries it from one place to another place. Generally topsoil where mostly vegetation takes place erodes very quickly. Too much soil erosion is a major concern as it exposes rocks underneath and very little grow on the rocks.

We can avoid soil erosion by plantation and forestation as roots of plants prevent erosion of soil. Vegetative cover and trees not only prevent soil erosion but also help in percolation of water into deeper layers. That is why deforestation is a big concern all over the world.

Q16. Discuss water-cycle in brief.

Water is one of the most important natural resource to terrestrial animals and plants as well as marine organisms for various life-processes. Water-cycle balances the quantity of water in our Earth. Previously we have learnt evaporation of water in chapter 01 – matter in our surroundings. Firstly water evaporates from seas, oceans, rivers and other water bodies. It falls back on the land as rain. Then it flows into seas and oceans via rivers. That is why seas or oceans never dry up. The whole process i.e. evaporation of water from water from water bodies to returning the same back to water bodies is the water-cycle.

Rain water passes through or over land or rocks which contains various soluble minerals during its journey from land to river. So rain water dissolves various minerals and nutrients into it These nutrients are important to marine organisms for their survival. Rain water does not fully flow back to the water bodies because some percentage seeps into the soil. This enriches underground reservoir of fresh water. Underground water partially resurfaces through springs. We also bring underground water through tube-wells and wells.

Q17. Discuss importance of nitrogen in living organisms in brief.

Nitrogen is 78% of air and very essential nutrient for all life-forms. Nitrogen has its presence in many molecules like proteins, nucleic acids (DNA and RNA), vitamins etc. Also some important biological compound like urea, alkaloids etc. contain nitrogen. These nitrogen compounds are very essential nutrient for living organisms.

Q18. How does organism intake nitrogen?

Surprisingly most life-forms can not convert nitrogen into required forms of nitrates and nitrites by taking nitrogen directly from air. Only few forms of bacteria are able to do so and they are either free living or associated with some species of dicot plants. Generally these bacteria are found in the roots of legumes in special structure called root-noodles.

Apart from this biological processes, conversion of nitrogen into nitrates and nitrites happen through physical processes. Lightning causes high temperature and pressure in the air. This condition in the air converts nitrogen into oxides of nitrogen. These oxides later dissolve in rain water and gives nitric and nitrous acids Life-forms utilizes these when it falls on land with rain water.

Q19. Discuss nitrogen-cycle in brief.

Generally plants intake nitrates and nitrites and converts them into amino acids. Later amino acids take part in the formation of proteins. Apart from this, some biochemical pathways also produce essential compounds of nitrogen. Animal consumes these molecules and compounds of nitrogen. When organism dies, bacteria present in the soil converts various nitrogen compounds back into nitrates and nitrites, some other forms of bacteria converts the nitrates and nitrites into elemental nitrogen. Therefore, summarily we say that nitrogen-cycle is the journey in which nitrogen passes elemental form to simple molecules (in soil and water) to complex molecules (in living organisms) and back to simple nitrogen molecule.

Q20. Discuss the presence of carbon in our Earth.

We find carbon in both elemental and compound forms in our Earth. Diamond, graphite etc. are the examples of elemental form of carbon. On the other side, air contains carbon compound i.e. carbon dioxide. Various minerals also contain carbon compound as carbonate and hydro-carbonate salts. Organisms have presence of carbon containing molecules like protein, fats, carbohydrates, nucleic acid and vitamins. Carbonate salts also form endoskeletons and exoskeletons of various animals. In fact, all life-forms are based on these carbon molecules.

Q21. Discuss carbon-cycle in brief.

Some organisms (mainly plantae group) contain chlorophyll in their cells. Presence of chlorophyll helps to perform the process of photosynthesis during daylight. During this process carbon dioxide from the air or dissolved in water is converted into glucose molecules. These molecules provide energy for the synthesis of other biologically important molecules. Also these glucose molecules are converted into other substances through various biochemical pathways. Through these ways carbon is incorporated into life-forms.

How does carbon return back to atmosphere? It happens through the process of respiration. Respiration is the process of utilizing of glucose molecules to provide energy to living things. During this process glucose is converted back into carbon dioxide. The process may or may not involve oxygen.

Combustion of fossil fuels is another process to add carbon dioxide in the atmosphere. Industries extensively burn fossil fuel for their energy requirement. Also the processes like cooking, heating, transportation etc. involve combustion of fossil fuels. Due to this excessive use of fuels by the industries, presence of carbon dioxide into the atmosphere is said to have doubled. In conclusion, we may say that carbon-cycle is the to-and-fro journey of carbon dioxide in the atmosphere through various physical and biological activities.

Q22. What is greenhouse effect? What is greenhouse gas?

Greenhouse is such an enclosure where heat is trapped to maintain warm environment inside it. Generally tropical plants are kept inside greenhouses so that it can get warm environment during the winters in colder climates. The term greenhouse gas is used to describe an atmospheric phenomenon. Our atmosphere contains various gases. Greenhouse gases are those gases which prevent the escape of heat from our Earth.

Greenhouse effect ⇒

The atmosphere contains various greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), ozone (O₃), water vapour (H₂O) etc. If percentage or quantity of these gases gets increased in the atmosphere, then it will prevent the escape of heat more from the Earth. As a result average temperature on Earth’s surface will increase. We term this phenomenon as greenhouse effect. Present average temperature on Earth’s surface is 15^oC (59^oF). On the other side if there were no greenhouse gases in the atmosphere, then average temperature on Earth’s surface would be in minus range [as low as 0^oF (-18^oC)]. So percentage of greenhouse gases should be balanced in the atmosphere to avoid adverse effect like global warming.

Q23. Discuss the presence of oxygen in our Earth.

Like nitrogen, oxygen is also part and parcel of most biological molecules like carbohydrates, nucleic acid, proteins and fats or lipids. We know that air contains elemental oxygen to the extent of 21%. Air has also presence of combined forms of oxygen like carbon dioxide (CO₂), carbon monoxide (CO), vapour (H₂0) etc. Our Earth’s crust has presence of oxygen in forms of oxides of metals and silicon, carbonate, sulphate, nitrate and other minerals. Though oxygen is very essential for life-forms but there are also some exceptions like killing of bacteria by elemental oxygen, nitrogen-fixing by bacteria in absence of oxygen etc.

Q24. Discuss oxygen-cycle in brief.

Oxygen-cycle is the process through levels of oxygen in the atmosphere is balanced.

Generally there are three major processes through which oxygen is consumed or used up.

These are combustion, respiration and production of oxides of nitrogen.

How does oxygen return back to atmosphere? It happens through one major process i.e. photosynthesis.

Q25. What is ozone layer?

We know that air contains elemental oxygen in form of diatomic molecule apart from various oxides. But there is also a layer of tri-atomic molecule of oxygen in the upper reaches of the atmosphere. This tri-atomic molecule of oxygen is called ozone. Ozone is written is O₃ and it is poisonous also. It is a good luck for life-forms that poisonous ozone (O₃) gas does not exist near to Earth’s surface.

Q26. Why ozone layer is important to us? What is affecting ozone layer?

The layer of ozone (O₃) in the atmosphere is very important to us as it absorbs harmful radiations from the Sun. It acts as a cover or shield over Earth’s surface and prevents harmful radiations from the Sun. The harmful radiation from the Sun, if reaches Earth, may damage or destroy many life-forms in the Earth. So existence of ozone (O₃) layer in the atmosphere is a must for us.

Human activities are affecting this ozone (O₃) layer and even depleting it. Recently a hole is observed in ozone (O₃) layer above Antarctica. Various man-made activities produce CFCs compounds. These CFCs are carbon compounds containing chlorine and fluorine. Most dangerous is that these compounds are very stable and not bio-degradable. After reaching ozone (O₃) layer, these CFCs react with ozone molecules and thus it results in reduction of ozone (O₃) layer.

In-Text Questions & Answers | NCERT Class 9 Science Chapter 14 | Natural Resources

In-Text Questions & Answers | NCERT Class 9 Science Chapter 14 | Natural Resources |Page Nos. 193

1. How is our atmosphere different from the atmosphere on Venus & Mars?
Write down the answer of Q2 in detail.

2. How does the atmosphere act as a blanket?
Write down the answer of Q3 in detail.

3. What causes winds?
Write down the answer of Q5 in detail.

4. How are clouds formed?
Write down the answer of Q6 in detail.

5. List any three human activities that you think would lead to air pollution.
a. Burning of fossil fuels i.e. coal & petroleum adds carbon particles to air. These activities also produce & add large amount carbon monoxide & carbon dioxide into atmosphere. b. Generally industries release carbon monoxide, carbon dioxide, heavy metals, oxides of nitrogen, hydrocarbons, sulphur dioxide etc. into atmosphere. c. Refrigeration uses CFCs (chlorofluorocarbons) which cause depletion of ozone layer.

In-Text Questions & Answers | NCERT Class 9 Science Chapter 14 | Natural Resources |Page Nos. 194

1. Why do organisms need water?

Water is most essential to survive. It acts a medium for many chemical reactions or cellular processes that are taking place in our body. Water helps in transportation of molecules & other substances in a dissolved state from one part to another part within the body. Plants need it for photosynthesis. Also terrestrial animals uses water to transport minerals & to get rid of waste from their body. We also require water for many other important purposes. For example – drinking, cooking, hydro-power generation, industrial needs, irrigation etc.

2. What is the major source of fresh water in the city / town / village where you live?

The major sources of fresh water in the city / town / village where we live are
a. Storage of rain water in tanks, dams etc.
b. Surface water sources i.e. rivers, ponds, lakes etc.
c. Mountains covered with snow & ice.
d. Underground water. We may lift it through different ways.

3. Do you know of any activity which may be polluting water source?

Water may get polluted through following ways –
a. Using fertilizers & pesticides in farming.
b. Dumping of waste in rivers, lakes etc.
c. Garbage or sewage from cities & towns.
d. Chemical waste from factories.
e. Also hot water from various industries because sudden change in temperature affects the aquatic organisms. Especially it affects eggs and larvae of the aquatic organisms. Thus it affects the breeding of the aquatic organisms.

In-Text Questions & Answers | NCERT Class 9 Science Chapter 14 | Natural Resources |Page Nos. 196

1. How soil is formed?

Write down the answer of Q12 in detail.

2. What is soil erosion?

Soil erosion is the removal of top soil by air & water. The flowing water & wind wash away the top soil. As a result, the rocks underneath is exposed. Soil erosion also leads to flooding & desertification. It also causes soil infertility. Because, soil erosion causes removal of humus & living organism with top soil.

3. What are the methods of preventing or reducing soil erosion?

Write down the answer of Q15 in detail.

In-Text Questions & Answers | NCERT Class 9 Science Chapter 14 | Natural Resources |Page Nos. 201

1. What are the different states in which water is found during the water cycle?

During water cycle ⇒ a. Water exists as liquid in various sources in rivers, ponds, lakes, seas etc. We also get it as liquid in case of underground water & rain water. b. Water evaporates from different water bodies & also through the transpiration process by plants. After that it exists in gaseous state in the form of water vapour. c. Clouds are condensed state of water vapour. Snow & ice are solid state of water.

2. Name two biologically important compounds that contain both oxygen & nitrogen.

Nitrites (NO₂^–) & Nitrates (NO₃^–) are two biologically important compounds that contain both oxygen & nitrogen. Because plants only can absorb nitrogen in the form of Nitrites (NO₂^–) & Nitrates (NO₃^–).

3. List any three human activities which would lead to an increase in the carbon dioxide content of air.

a. Burning of fossil fuels i.e. coal, petroleum etc. increases carbon dioxide in air. b. The decomposition process of dead bodies & organic wastes releases carbon dioxide in the atmosphere. c. Breathing also releases carbon dioxide as a product of respiration.

4. What is the greenhouse effect?

Write down the answer of Q22 in detail.

5. What are the two forms of oxygen found in the atmosphere?

Ozone (O₃) & oxygen (O₂) are the two forms of oxygen found in the atmosphere. Ozone (O₃) is triatomic molecule of oxygen. It exists at the upper layers of atmosphere. Oxygen (O₂) i.e. elemental oxygen is generally found in the form of a diatomic molecule.

Natural Resources | Exercises Questions & Answers | NCERT Class 9 Science Chapter 14 | Page Nos. 201 - 202

1. Why is atmosphere essential for life?

A⇒ Basically air is bad conductor of heat. This property of air keeps the average temperature of the Earth not only during the day but also during the course of whole year. Air prevents the abrupt and sudden rise of temperature during daylight hours and retards the escape of heat into outer space during night. Thus air gives a blanket-like covering to the Earth and maintains ambient temperature for living organisms. B⇒ Also atmosphere contains ozone in the upper layer which protects life from harmful ultraviolet radiation. C⇒ The atmosphere is a mixture of various gases like nitrogen (N₂), oxygen (O₂), argon (Ar), carbon dioxide (CO₂), water vapour and other gases which play life supporting role in Earth. D⇒ Movement of air causes winds in the atmosphere which decides rain & rainfall pattern. E⇒ Oxygen cycle, water cycle etc. are not possible without atmosphere.

2. Why is water essential for life?

3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as as resource?

Plants intake essential nutrients from the soil to prepare food through photosynthesis. Thus soil provides anchorage to the plants for their growth & developments. On the other side, human & other heterotrophic organisms depend on plants for food & other essential nutrients. Soil plays as natural habitat to various organisms i.e. fungi, bacteria etc. which in turn improve soil fertility. Thus we get that living organisms are dependent on the soil. But some are directly dependent & some are indirectly dependent.

Organisms that live in water are not totally independent of soil as as resource. Because these organism are dependent on aquatic plants for their food & support. When the aquatic plants & animals die, they are decomposed by the living microbes in soil. This process return the essential nutrients back to the water for sustenance of the aquatic plants.

4. You have seen weather reports on television & in newspapers. How do you think we are able to predict the weather?

We see weather reports on television & newspapers. Basically India Meteorological Department forecasts weather report in India. It has presence in different cities of the country. They collects various information like – a. daily max. & min temperature, b. humidity, c. direction & speed of wind, d. cloud pattern, e. depression zone etc. with the help of instruments installed at different location all over the country. The advancement in satellite technology help weather department to predict even more accurate nowadays like forecasting of cyclone.

5. We know that many human activities lead to increasing levels of pollution of the air, water-bodies & soil. Do you think that isolating these activities to specific & limited areas would help in reducing pollution?

Of course, isolating human activities to specific & limited areas would reduce pollution of air, water & soil. For example, if we set up industries in isolated regions, it will reduce pollution to some extent. Because these industries in isolated regions will not contaminate fertile lands, water bodies etc.

6. Write a note on how forests influence the quality of our air, soil & water resources.

Plants & animals release carbon dioxide to the atmosphere as a product of respiration. Plants use this carbon dioxide to manufacture their food by photosynthesis & release oxygen as a by-product. Thus forests clean the air by adding oxygen to it & control greenhouse effect.

Deep-rooted plants hold soil particles tightly. As a result, it reduces soil erosion. Forests, as a component of bio-geochemical cycle, help in cycling of nutrients & returning them back to the soil. Thus it improves the soil fertility.

Plants lose water to the atmosphere through transpiration. That water is later converted into vapour, clouds etc. which cause rain. Thus forests enriches the water resources in the earth.

Natural Resources – To Be Continued – Natural Resources