Natural Resources

True

Biosphere contains all the planet’s living things. It includes all the microroagnisms, animals, and plants of Earth.

False

Ozonsphere is located in the stratosphere of atmosphere from 20 to 30kms above earth.

False

Clouds are formed in troposphere of atmosphere. The bottom of troposphere is at earth’s surface.

All weather phenomenons occur in troposphere.

True

It is the upper layer of earth’s crust in which plants grow. It is made oup of organic matter and consists of rocks and clay particles.

True

75% of earth’s surface is covered with water and 96.5% of this water exists in oceans, 3.5% is fresh-water lakes and frozen water locked up in glaciers and the polar ice caps.

True

Combustion is a exothermic reaction between a reductant and oxidant (oxygen) , that produces carbon dioxide and water.

True

Heat from the sun and earth’s temperature collide to form wind.

False

Suphur dioxide and nitrogen oxides in the air mix with water, oxygen and other chemicals and fall on earth as acid rain.

False

One chlorine atom destroys 100,000 ozone molecules when it combines with bromine atoms in the stratosphere.

Compounds that release chlorine when they are exposed to UV light in stratosphere are called ozone-depleting Substances (ODS).

True

Water is necessary for all life forms to sustain on earth. Plants grow when they get sufficient amount of water for carrying out photosynthesis. Similarly, animals and human beings need water to drink and for other purposes. Rainfall is one o the major sources of water. High amount of rainfall will help in all the life forms to flourish.

False

Soil has minerals in it. When rain or flood washes away the soil, the water ultimately collects in water bodies. The minerals and nutrients that were present in soil get transferred to water bodies in this process. These minerals and nutrients are used up by the aquatic organisms.

True

Gaia hypothesis was proposed by James Lovelock. The hypothesis is describes as viewing the earth as a single organism.

True

Fertilizers and pesticides contain chemicals. Excess amount of these chemicals in the soil are harmful to microorganisms like bacteria, as a result of which they die.

True

Methane is a component of natural gas. Unused methane, if leaks into the air, acts as a green house gas, it absorbs sun’s heat and warms the atmosphere thus causing global warming.

True

Rhizobium leguminosarum is a gram negative soil bacteria that fix nitrogen.

A-Food molecules ; photosynthesis produces food molecules i.e. glucose.

B¾ Photosynthesis; Co2 is used in photosynthesis.

C¾ Respiration; Respiration releases CO2 so C is respiration

(b) The given cycle is oxygen cycle because atmospheric oxygen is taken up in C respiration to give out CO2 which is used in B photosynthesis to produce food i.e. A

(a) The given cycle is Nitrogen cycle because the green plants release ammonia by ammonification. The ammonia released is converted into nitrite which are further converted into other nitrates.

(b)

A—Ammonification; The green plants release ammonia by utilizing nitrogen in soil.

B—Ammonia; released from plants by ammonification.

C—Nitrite; Ammonia is converted into nitrite by nitrifying bacteria Nitrosomonas.

D— Nitrates. Nitrite is further converted into other nitrates by Nitrobacter.

(c)In the absence of setp E, i.e. denitrifying bacteria, atmospheric nitrogen wil not be replenished as nitrates wont be converted into N2 by denitrifying bacteria.

(a) Sulphuric acid (H₂OS₄) and Nitirc acid (HNO₃) are present in acid rain. Sulphur oxides and oxides of nitrogen combine with water and oxygen in air and fall on earth as acid rain in the form of Sulphur and nitric oxides.

(b) Sulphur and nitric oxides present in acid rain corrode the marble, limestone, sandstone. When acid rain falls on them it breaks them down into fine powdery substances which is later washed away by rain.

Taj mahal that is made of marble is being corroded by acid rain as the acid rects with the marbles.

(i) Minamata disease is a disease that first occurred in people of Japan. The water bodies polluted with high levels of mercury were consumed by people which caused toxicity in their bodies and lead to this disease. The symptoms noticed were- ataxia, numbness in the hands and feet, muscular weakness, and damage to hearing and speech.

ii) Itai-Itai is a disease that also occurred in people of Japan in 1912 by consuming water polluted with high levels of Cadmium. The disease is characterized by severe pain in joints.

(a) Nitrification is the conversion of ammonia into nitrate. It is carried out by bacteria like Nitrobacter, amd Nitrocystis.

(b) Pseudomonas is a denitrifying bacteria that converts nitrates in soil to free atmospheric nitrogen.

(c) Azobacter, Cyanobacteria, Anabaena and Clostridium are some bacterias that play a role in biological nitrogen fixation i.e. they convert nitrogen in earth’s atmosphere to ammonia NH3.

Biosphere is living mantle of Earth which constitutes all the life forms of the planet.

Biosphere has 3 divisions

● Lithosphere (land),

● hydrosphere (water), and

● Atmosphere (air).

Natural resources refer to those resources that occur naturally without the interference of mankind. These are resources available in abudance for mankind. They may be renewable and non-renewable.

● Renewable resources are those that can be replenished. For eg- air, water, wind, sun energy.

● Non-renewable resources are those that cannot be replenished once exhausted. For eg- minerals, fossils and soil.

Resources are supply of materials that can be transformed to obtain benefit by either consuming or using.

(1) Inexhaustible resource: These are resources that are available in abundance and cannot be exhausted ever. Eg- Air.

(2) Renewable exhaustible resource: These are those resources that may get exhausted by excessive use but can be re-obtained in nature. Eg- Forests; they might disappear one day if deforestation continues but planting seeds can regenerate them.

(3) Non-renewable exhaustible resource: These resources once exhausted cannot be replenished.

Eg-Fossil fuels, minerals.

Energy from sun, air are examples of inexhaustible natural resources. They will not ever get exhausted.

Atmosphere is defined as layers of gases surrounding the earth surface. It is a mixture of gases like nitrogen-78%, oxygen-21% and 1% other gases.

Mars, venuc and Pluto are planets that have atmosphere. They are gas giants.

● Major component of atmosphere of Earth is nitrogen 79% and oxygen 20%, small fraction of carbon dioxide and other gases.

● Atmosphere of Venus and Mars is composed mainly of carbon dioxide ranging from 95-97%.

a) Ozone layer is present in Stratosphere of the atmosphere. It protects earth from harmful Ultraviolet radiations coming from the sun.

b) Troposphere has most of the atmospheric gases. All the weather phenomenons take place in this region of atmosphere.

1% of atmospheric gases are carbon dioxide and other gases on earth. Out of which, 0.03% is carbon dioxide present in the earth’s atmosphere.

Air is a mixture of gases like carbon dioxide, nitrogen, oxygen and water vapour that occurs in the atmosphere.

Life is not possible on Mars and Venus because these planets have 95-97% of carbon dioxide and no oxygen to sustain life.

2 important biological processes in which air is essential is

1- Respiration i.e. breathing in of oxygen from the atmosphere for sustaining life.

2- Photosynthesis- uptake of carbon dioxide from the air to produce food and release oxygen.

Nitrogen with 79% is the highest in concentration in air. Oxygen occupies 29%. 1% is occupied by carbon dioxide and other gases.

Air is called the breath of life because it contains oxgen and carbon dioxide. Carbon dioxide is used by plants to produce food and release oxygen.
Oxygen is breathed in by human beings and animals to sustain life.

Dust particles present in the atmosphere forms nuclei for condensation of water vapour in atmosphere.

The water vapour condense around these dust particles that further result in precipitation

In coastal areas, air from high pressure area over land rushes to fill the area over low pressure area of water i.e. from land to sea.

Air currents coming from Allahabad would be directed westwards after it is intercepted by Himalaya in north due to creation of low pressure.

Rain gauge is a device used to collect andmeasure the amount of rain that falls.

Air pollution is defined as introduction of unwanted, harmful substances/molecules into the atmosphere that harms the life forms on earth.

Smog is a type of air pollution occurring from emissions from vehicles and industries. This smog reacts with sunlight in atmosphere and form secondary pollutants.It lowers visibility and affects living organisms.

Burning of fossil fuels release oxides of Sulphur, and nitrogen into the air. Nitogen gets oxidized and forms its oxides. These chemicals combine with water and fall as acid rain on earth. The pH of this rain water is less than 5.

Lichens are sensitive to Sulphur dioxide component present in air. These compounds readily dissolve in water and produce highly reactive acidic ions which disrupt photosynthesis.

Ozone depleting substances are responsible for ozonedepletion.
Chlorofluorocarbons are such air pollutants that have chlorine atoms. 1 chlorine atom

Carbon dioxide is the major green house gas responsible for causing global warming as it traps infrared radiations which in turn causes the earth’s temperature to rise thus causing global warming.

ozone layer blocks Ultraviolet radiations coming from sun to reach earth’s surface and thus protects us from various diseases like cataract etc.

Incomplete combustion of carbon containing fuels like gasoline, natural gas, oil, coal etc produces carbon monoxide.

ii- Carbon monoxide has more affinity for haemoglobin because it displaces oxygen and quickly binds, thus allowing very little oxygen to be transported through body cells.

Calcium Carbonate is present in marble that reacts with acids of acid rain. Acids react with calcium compounds to create gypsum which later flakes off.

2.5-2.75% of water on earth is fresh water. The major part of this fresh water is present in glaciers, ice and snow (1.75-2%), 0.5-0.75% as fresh groundwater and about 0.01% as surface water in lakes and rivers.

The amount of rainfall that earth receives determines the density and richness of biota because plants need water to grow; it is one of major requirements of biota.

Regions of north eastern India and Western ghats are rich in diversity. Western ghats start near border of Gujarat and Maharashtra, running through states of Goa, Karnataka, kerala and Tamil nadu ending at Kanyakumari. These are listed in hot-spots of biological diversity in the world.

Arid areas like Rajasthan and part of Jaisalmer, Thar dessert are areas with very poor vegetation.

Water harvesting is collection and storage of mostly rainwater into tanks or reservoirs before the water is driven away by surface runoff.

Contamination of water bodies with undesirable substances like fertilizers, pesticides or poisonous substances, thus degrading the water quality and making it unfit for drinking and other purposes is defined as water pollution.

Pathogens like bacteria, viruses, protozoan worms and protozoa usualy from sewage waste, cause water pollution. Eg-Coliform bacteria cause water pollution.

Three water pollutants are

● Waste from farms i.e. fertilizers and pesticides. The chemicals in them pollute the water.

● Industries release their waste products directly into the rivers thus degrading water quality.

● Disease causing agents like bacteria, viruses and protozoans enter the sewage system. This sewage is ultimately discharged into water bodies like sea

Sewage refers to waste and excrement of humans that is carried in sewers by municipal drains.

Disease caused by mercury pollution in water is known as Minamata disease. It was first observed in the people of Japan. Methylmercury poisoning occurred in several places of japan because industries discharged mercury into rivers.

Thermal pollution is defined as change in average temperature of water that results in degradation of water quality. Industries use water as coolants in power plants thus causing thermal pollution.

The topmost layer of earth’s crust that supports life forms is known as soil. Soil decides the diversity of soil in a area.

Physical agents that cause weathering of rocks are

● Thermal stress i.e. Contraction and expansion of rocks by changes in temperature.

● Wind is another strong physical agent that brings about weathering of rocks.

● Heavy rainfall.

Two processes that contribute to soil formation are-

● Weathering of rocks by mechanical, biological and chemical processes.

● Decomposition of organic matter in the crust adds to humus content and thus healthens soil growth.

Soil pollution is defined as contamination of soil with toxic chemicals, pollutants, fertilizers and pesticides that make the soil unfit for plant growth and degrade its quality.

2 effects of soil erosion are-

● Reduction in growth of new plants as the topsoil erodes away and the remaining soil is not that fertile to support growth.

● Soil erosion leads to contamination of water sources and pollutes the public areas.

Paedogenesis is reproduction by young or larval animals which retain its larval features, on rocks. It is the process of formation of soil from rocky crust of earth’s surface.

Weathering is breaking down of rocks to form soil by temperature, air and water.

Weathering occurs by 3 processes-

● Physical/Mechanical- Breakdown of rocks into smaller pieces. Eg- frost shattering

● Biological- Disintegration of rocks by activities of living organisms.

● Chemical- it occurs when rocks are worn away by chemical changes.

Process of formation of humus during decomposition of organic material in soils is known as humification.

Topsoil is the uppermost layer of soil, having the maximum concentration of organic matter and microorganisms & supporting the earth’s diversity.

A windbreak is a shelterbelt made of rows of trees planted in a manner to provide shelter from wind and protect soil from erosion.

Terracing refers to cutting plane piece of land into several coninous platforms to perform effective farming. Terracing slows down water flow and thus prevents soil erosion.

Capillary water is the water present in soil that can be absorbed by plants. This water is present in the soil after gravitational water has been removed. Capillary water forms a film around the soil grains and is pulled up by roots of plants and thus absorbed.

Detritus refers to organic matter produced by decomposition of organisms. Usually dead remains of plants and animals are detritus.

Detritivores are animals that feed on dead organic material like plant detritus. Earthworms, fungus are detritivorethat feed on dead and decomposing organic matter.

Methane burp refers to release of methane in large quantities. Usually methane burp occurs in ruminants like Cows. Methane hydrates/methane clatharate have large amount of methane trapped in them. When they melt, a large amount of methane is released known as methane burp.

A biogeochemical cycle is a pathway by which essential chemical substances move through the biotic and abiotic components of Earth. Nitrogen, oxygen, phosphorous, Sulphur, water cycles are some important biogeochemical cycles.

Biogeohemicals are essential elements present on the earth that are required by living oranisms. These elements include N, O, P, S, C, H₂O.

Marine organisms receive continuous supply of nutrients from the rivers that come down from high altitudes. These rivers bring down silt that has nutrients, obtained by flowing over rocks at high altitudes.

The process of evaporation of water and falling on the land as rain and later flowing back into the sea via rivers is known as the water-cycle. The other name for water cycle is Hydrological cycle.

The conversion of atmospheric nitrogen into ammonia NH3 is known as nitrogen fixation. Bacteria that perform nitrogen fixation are either free living or they may form symbiotic associations with other organisms.

Eg- protozoans, termites.

Rhizobia are soil bacteria that fix themselves in root nodules of legumes and then carry out nitrogen fixation.

The process by which bacteria convert organic nitrogen to ammonia is known as ammonification. After ammonification has occurred, ammonium is converted into nitrite and nitrate. Ammonification is also known as mineralization.

Bacteria like Bacillus, Clostridium and Streptomyces acause ammonification. Bacillus ramosus is one such ammonifying bacteria.

Conversion of ammonium to nitrite and nitrate by bacteria is known as nitrification.

There are 2 types of bacteria involved in nitrification- nitrite and nitrate.

● Nitrite bacteria like Nitrosomonas oxidize ammonium to nitrite.

● Nitrate bacteria like Nitrobacter oxidize nitrite to nitrate.

The loss or removal of nitrogen usually bu escape into the air from soil is known as denitrification.

Formation of carbonate and limestone rocks causes a long term withdrawl of carbon from the carbon cycle as they take a large amount of carbon and once formed they take years to degrade.

The major reasons for increase in concentration of carbon dioxide in the atmosphere are burning of fossil fuels and cutting down of trees.

Fossil fuels like coal and petroleum when burned, they release carbon dioxide.

Use of carbon dioxide present in the atmosphere also decreases when trees don’t are cut down therby constantly helping in icreasing the carbon dioxide content in the atmosphere.

A greenhouse is a glass house where plants, flowers and vegetables are grown. These greenhouses warm up during daytime due to solar radiations therby heating plants and soil. This heat escapes throughout the night.

Greenhouse effect is a phenomenon that heats the earth’s surface. The greenhouse gases prevent infrared diations from escaping the earth which results in heating of the earth’s surface.

Greenhouse gases are gases that trap infrared radiations and prevent them from escaping the earth’s surface. This trapping of infrared rays thus results in an increase in temperature of earth known as global warming.

Global warming refers to an increase in earth’s temperature due to effect of greenhouse gases like carbon dioxide and methane.

Oxygen is replenished or released in nature by photosynthesis. Green plants take up carbon dioxide to prepare food. The results of the process is food (glucose) and oxygen molecules.

Ozone layer or ozone umbrella is a region in the earth;s stratosphere that absorbs Ultraviolet radiations coming from the sun and stops them from reaching living organisms on earth, thus preventing living organisms from a large number of diseases.

Ozone depleting substances are those substances that contain chlorine and/or bromine. These substances destroy the ozone layer. One single atom of chlorine destroys 1000 molecules of ozone.

Ozone hole is a part of ozone layer that has been depleted by ozone depleting substances in the atmosphere. It is found over Antarctica during winters. Ozone hole results in passage of UV radiations into earth’s surface thus causing diseases in people on earth.

Inexhaustible resources are those resources that are available in abundance and cannot be exhausted ever. Eg- Air is an inexhaustible resource.

Renewable exhaustible resources are those resources that may get exhausted by excessive use but can be re-obtained in nature. Eg- Forests; they might disappear one day if deforestation continues but planting seeds can regenerate them.

Non-renewable exhaustible resources are those that once exhausted cannot be replenished. Fossil fuels, minerals are all examples of non-renewable resources.

carbon dioxide is fixed by the following proceses-

a- Plants fix carbon dioxide by using it in photosynthesis and relasing oxygen.

b- Aquatic animals use dissolved carbon dioxide to make carbonate shells.

Dust particles act as nucleus for water droplets to form around in the atmosphere.

Water condenses around the dust particles to form clouds high in the atmosphere. When the clouds can no longer hold more water vapour, i.e. when they reach saturation, the water falls down on earth as rainfall.

A- Acid rain: Burning of fossil fuels release oxides of Sulphur, and nitrogen into the air. Nitogen gets oxidized and forms its oxides. These chemicals fall along with rainwater on earth thus causing acid rain.

B- Global Warming: Global warming refers to an increase in earth’s temperature due to effect of greenhouse gases like carbon dioxide and methane. These gases traps the infrared rays and doesn’t let them escape out from the earth’s surface which results in an increase in earth’s temperature as all the heat gets trapped in. This causes global warming.

a- Bronchitis characterized by the inflammation and swelling of the air passages between nose to lungs and throat to lungs

b- Immune system defects; it occurs due to constant breathing in polluted air

c- Pneumonia- an infection of lungs caused by breathing a flying bacteria

d- Asthma attacks because of inhaling various poisonous gases and constant suffocation owing to polluted air

Sulphuric and nitric acids are the two acids present in acid rain. Oxides of nitrogen and Sulphur dioxide in the atmosphere react with water, oxygen and other chemicals and fall on earth as Sulphur and nitric oxides in the form of acid rain.

Rainwater harvesting is collection and storage of rainwater into tanks or reservoirs before the water is driven away by surface runoff.

Carbon dioxide and methane are two greenhouse gases which contribute maxium toward global warming by trapping the infrared rays and not letting them escape the earth’s atmosphere thereby increasing the earth’s temperature.

Lead compound is added to petrol to ensure smooth burning of petrol in the vehicles. Lead compounds in petrol are harmful because the exhaust pipes of the vehicles release these toxic lead compounds whose inhalation leads to diseases like anemia, brain damage, and may even cause death.

Fresh water is obtained from underground water reservoirs and Rivers for human use.

Main sources of water pollution are-

● Waste from farms i.e. fertilizers and pesticides. The chemicals in them pollute the water.

● Industries release their waste products directly into the rivers thus degrading water quality. Industries also contribute to thermal pollution as the coolants discharged by them causes a change in the average temperature of water, therby degrading the water quality.

● Disease causing agents like bacteria, viruses and protozoans enter the sewage system. This sewage is ultimately discharged into water bodies like sea

Non-biodegradable substances are those that cannot be broken down or decayed by microorganisms into its base compounds or compounds that are safe for the environment. Plastic and metal products are non biodegradable substances.

Eutrophication is a phenomenon that occurs in water bodies. Fertilizers run of from crop fields lead to accumulation of the chemicals in water bodies which results in algal blooms. These alagal blooms thus block the sunlight from penetrating into the aquatic bodies. The aquatic plants thus do not get sunlight to synthesize food and oxygen, thus causing Eutrophication.

Eutrophication causes toxicity in water bodies and makes the water polluted. Also, since the oxygen content decreases, the biological oxygen demand increases. Less content of oxygen effects life forms and aquatic organisms die due to insufficient oxygen.

Chemicals, pesticides and heavy metals move up the food chain, get into aquatic bodies and are eaten by organisms like fishes which are in turn eaten by hawks/eagles. This process where the chemical enters the food chain and increase in concentration with increasing trophic level is known as biological magnification.

Heavy metals that result in diseases when magnified are mercury, cadmium, copper, lead etc.

Biological weathering refers to weathering by living organisms. Disintegration of rocks by activities of living organisms like plants grow in the cracks of rocks, break the rocks and withers them.

● Lichens that grow on rock suface release chemical substances that cuase rock to powder down and form thin layers of soil.

● Small plants like moss live on rock surface and cause the rock to break down.

Humus is the dark organic matter that forms in the soil when plant and animal matter decays. It contains many useful nutrients for healthy soil.

Functions of humus in soil are-

● Humus increases the fertility of soil;

● It also helps soil absorb and retain moisture

● Humus also promotes the formation of good soil structure.

● It supports microbial activity in soil, through which roots absorb nutrients

Two measures to prevent soil erosion are-

● Stopping deforestation and planting more and more trees so that roots bind to the soil and hold the soil together, thus preventing it from being eroded away.

● Making windbreakers from trees on the land to prevent erosion of soil by wind blowing across it.

Humification—The process of formation of humus during decomposition of organic material in soils is known as humification.

Mineralization- The decomposition or oxidation of the chemical compounds in organic matter into forms that are accessible by plants is known as mineralization.

● Hygroscopic water is the film of water tightly held by the soil particles and it is not available to the plant.

● Combined water is the amount of water that is present in the chemical compounds, which are present in the particles of soil. Combined water is also not available to the plant.

The main sources of carbon are-

● Burning of fossil fuels like coal, petroleum.

● Decompositon of organic material by decomposers results in release of carbon dioxide in the atmosphere.

Carbon monoxide is a colourless, odourles gas produced by burning of wood, fuels etc. The replacement of oxygen with carbon monoxide in red blood cells in our body leads to carbon monoxide poisoning. Carbon monoxide poisoning causes tissue damage and may even lead to death.

Air contains 78% nitrogen, 21% oxygen, 0.004% of carbon dioxide and small percentage of other gases. Amount of water vapour in the air varies with temperature. At 30 degree Celsius, air can contain 4% of water vapour, whereas at -40 degree Celsius, air cannot hold more than 0.2% water vapour.

Oxygen and carbon dioxide remain nearly constant in the atmosphere because a cycle operates in nature wherein these two gases are exchanged.

Plants take carbon dioixide CO2 from atmosphere to perform photosynthesis and release out oxygen O2 which is inhaled by man and animals in turn giving out carbon dioxide which plant use for photosynthesis. Thus this maintains a nearly constant level of oxygen and carbon dioixide in the atmosphere.

The atmosphere of the earth keeps the temperature of earth fairly steady by traping the heat during night and preventing the earth from freezing. The atmosphere also doesn’t allow excess sunlight to enter the earth and thus keep the average temperature fairly steady.

Unequal heating of landmass and water bodies by sun’s heat generate air movement and as a result wind is produced. When the air around landmass gets heated, it becomes lighter and rises up creating a region of low pressure. Air from high pressure region escapes to the low pressure region thus generating wind currents.

● Incomplete combustion of fossil fuels like coal and petrol adds to carbon dioxide concentration in the atmosphere.

● Deforestation is one of the major causes of increase of CO2 concentration in the atmosphere because plants that utilize CO2 in the atmosphere are cut down so the CO2 is not utilized and keeps on increasing.

No answer

Heat energy can be transferred by convection when there are temperature differences between two parts of a liquid.

The formation of convective currents can be demonstrated by following experiment-

Required- Beaker, water, Potassium permanganate VII, Bunsen burner

Potassium Permanganate VII is a colored compound that dissolved in water on heating.

Take water in a beaker and put potassium permanganate VII into it and put the contents of beaker to heat on a Bunsen burner. This chemical compound will dissolve slowly in water and the movement of this colored compound will be visible thus showing the formation of convective currents.

Pressure gradient, Coriolis effect and friction influence the movement of air.

● Pressure gradient- Air moves from areas of high pressure to areas of low pressure as observed during land and sea breeze.

● Coriolis effect- is the deflection of moving air caused by the rotation of the earth.

● Friction- It only effects the air movement in contact with the Earth. Friction slows down the air and if the air slows down, Coriolis effect has more effect then of air movement.

Water evaporates from earth surface from water bodies, precipitation by plants. This water vapour condenses around dust particles and forms clouds. When clouds can no longer hold more water vapour, i.e. when the clouds reach saturation, the water falls on earth as rain fall.

no answer

The major components of air pollution are Sulphur oxides, oxides of nitrogen, carbon monoxide. These are released from burning of fossil fuels like coal and petroleum. Ozone is also a gaseous pollutant that forms smog.

Burning of fossil fuels release oxides of Sulphur, and nitrogen into the air. Nitogen gets oxidized and forms its oxides. These chemicals combine with water and oxygen fall as acid rain on earth in the form of Sulphur and nitric oxides, with water having a pH less than 5. Acid rain reacts with metals & corrodes it, also it reacts with calcium containing substances, therby producing gypsum which then flakes off.

Smog is a type of air pollution occurring from emissions from vehicles and industries. This smog reacts with sunlight in atmosphere and form secondary pollutants.

It lowers visibility during winters and affects living organisms in the form of diseases.

Air pollution effect health and causes various respiratory diseases in humans. Some of them are-

a- Bronchitis characterized by the inflammation and swelling of the air passages between nose to lungs and throat to lungs

b- Immune system defects; it occurs due to constant breathing in polluted air

c- Pneumonia- an infection of lungs caused by breathing a flying bacteria

d- Asthma attacks because of inhaling various poisonous gases and constant suffocation owing to polluted air

In coastal areas-

● Land gets heated faster than sea during daytime so a low pressure exists on land and high pressure on sea. So the wind blows from sea(region of high pressure) to land(region of low pressure) during the day.

● At night, the land cools down and has high pressure area, while the sea now has low pressure area. The wind direction changes at night and wind flows from land to sea.

The atmosphere of the earth keeps the temperature of earth fairly steady by traping the heat during night and preventing the earth from freezing. The atmosphere also doesn’t allow excess sunlight to enter the earth and thus controls the climate

The main layers of atmosphere are-

● Troposphere- It is the closest layer to the earth surface. All the weather phenomenons occur in this layer. It begins at the surface of earth and extends to 4-12 miles. It is also known as lower atmosphere.

● Stratosphere- Temperature rises in this layer but is below freezing. It extends to 30-35 miles above the earth’s surface.

● Mesosphere-it lies above 3-35miles from the earth surface. The air here is thin and the molecules are large distance apart.

● Thermosphere- it rises several hundred miles from the earth surface and lies from 50-400miles. Temperature in this layer can be as high as 2000 degree centigrade.

● Exosphere- Extends from top of thermosphere to 6200 miles. The layer contains very few atmospheric molecules which can escape into space.

Natural sources of air pollution are-

● Forest fires produce trace gases and smoke.

● Bacteria spores, pollens are natural pollutants of air.

● Volcanic eruptions releases gases and ash.

● Marsh gases are released by decay of organic matter in marshy places.

Man-made sources of air pollution are-

● Industrialisation releases toxic gases into the atmosphere through exhaust pipes.

● Vehicles that run on fossil fuels like petrol also release toxic compounds like that of lead and contribute to air pollution.

● Nuclear explosions.

● Deforestation leads to an increase in concentration of carbon dioxide in the atmosphere.

Unequal heating of landmasses causes the warm/heated air to rise up. As the warm air rises up it expands and cools down. Warm air can hold water vapour well but cool air is incapable of holding water vapour. So the water vapour condenses on the dust particles already present in air and a tiny droplet is formed around the dust particles thus forming clouds.

Clouds are formed in the earth’s Troposphere where weather phenomenon occurs.

Global warming refers to an increase in earth’s temperature due to effect of greenhouse gases like carbon dioxide and methane.

Some effects of global warming are-

● Due to increased global warming, the level of the sea will rise which will lead to flooding and this will in turn create havoc in human life.

● As the temperature becomes warmer, it can affect the health of humans and the diseases they are exposed to.

● With the increase in the rainfall water borne diseases are likely to spread like malaria. The earth will become more warm and as a result heat waves are likely to increase that can cause a major blow to the people.

● Plants will find it harder to survive when temperature increases and will die. Plants are the major source of food for human beings and as a result food shortage may occur.

Ozone molecules form when a single O atm reacts with oxygen O2 molecule.

Chlorine containing compounds are major reason for the corrosion of ozone layer. Chlorofluorocarbons and certain other ozone depleting substances that contain chlorine and/or bromine are responsible for depletion of ozone layer. CFCs are made of chlorine. One single atom of chlorine destroys 1000 molecules of ozone.

Effects of ozone depletion are-

● More skin cancer in humans due to ultraviolet radiations which will easily reach the skin cells through stratosphere if ozone layer depletes.

● UV radiations would also damage parts of eyes thus causing cataracts, blindness and other diseases.

● Immunosuppression- UV radiations could damage the immune system.

Burning of fossil fuels release oxides of Sulphur, and nitrogen into the air. Nitogen gets oxidized and forms its oxides. These chemicals combine with water and fall as acid rain on earth. The pH of this rain water is less than 5. Acid rain reacts with metals & corrodes them, also it reacts with calcium containing substances, therby producing gypsum which then flakes off.

Rainwater harvesting refers to collection and storage of rainwater before it is lost as surface runoff.

Various methods of rain water harvesting are as follows

● Surface runoff harvesting- Rainwater that flows off from surface is collected and used to recharge aquifers.

● Roof top rainwater harvesting- Roof acts as a catchment where the rainwater is collected. This collected water is stored in a tank or diverted to artificial recharge system.

The weather conditions that exist in an area for long periods of time is known as climate of that area.

Weather refers to condition of the atmosphere at a place for a period of time. All the weather phenomenons occur in the troposphere layer of the atmosphere.

Chlorofluorocarbons contain chlorine and fluorine that are responsible for depletion of ozone layer. One single atom of chlorine destroys 1000 molecules of ozone. If ozone layer depletes, UV radiations from the sun would reach the earth surface and life on earth will suffer from diseases.

Weathering is breaking down of rocks to form soil by temperature, air and water.

Various types of weathering are-

● Physical/Mechanical- Breakdown of rocks into smaller pieces. The rocks get heated up during the day and it cools down during night. This expansion and contraction due to heating and cooling of rocks lead to splitting of rocks. Water might enter the rocks in the cracks made by expansion and contraction. When this water freezes, the rocks widen and thus rocks break.

● Chemical- it occurs when rocks are worn away by chemical changes like the chemicals released by lichens. These chemicals cause the rock surface to powder own which forms layers of soil

● Biological- Disintegration of rocks by activities of living organisms like plant grow in the cracks of rocks thus breaking the rocks

Soil erosion is defined as blowing away of land surface i.e. soil by wind or water.

Soil erosion leads Reduction in growth of new plants as the topsoil erodes away and the remaining soil is not that fertile to support growth. Also it leads to contamination of water sources and pollutes the public areas.

Means of preventing soil from being eroded is practicing terrace farming which slows the running water and thus checks soil erosion. Another means of preventing soil erosion is practicing afforestation i.e. planting of trees on large scale which whill help in binding of soil tightly with the roots.

Lichens that grow on rock surface release chemical substances that cause the rock to powder down and form thin layers of soil. Small plants like moss also grow on the surface of rocks and cause them to break down.

Water is replenished in the sea through water cycle in nature.

Water in the atmosphere is converted into water vapor by the heat from sunlight i.e. water evaporates and turns into water vapour. Also, water vapour is present in the atmosphere from plants by transpiration from leaves. This water vapour condenses in the atmosphere and forms cloud. When enough water vapour has condensed, it falls down on earth in the form of rainfall. This water either seeps underground or flows into sea, rivers or lakes, thus replenishing the water that had evaporated by heat from sun.

The conversion of atmospheric nitrogen into ammonia NH3 is known as nitrogen fixation. Bacteria that perform nitrogen fixation are either free living or they may form symbiotic associations with other organisms.

Eg- protozoans, termites. Through the process of nitrogen fixation, free nitrogen of air is converted into ammonia and nitrate, which is taken up by plants. In plants, nitrate is converted into amino acids, nucleotides, proteins, and other nitrogenous compounds.

Nitorgen is replenished in atmosphere by nitrogen cycle.

It is a process by which nitrogen is converted into various chemical forms and is made available to living organisms.

● Nitrogen fixation takes place by the action of microbes, inert nitrogen breaks down in the air and combines with oxygen to form nitrous oxide.

● Nitrifying bacterias in the soil take up this atmospheric nitrogen and make it available for plants. Plants get this nitrogen.

● Later when they decay, the nitrogen is returned back into the environment. In the soil there are some denitrifying bacterias too, they break down nitrate and release nitrogen into the atmosphere thus replenishing nitrogen in the atmosphere.

Carbon is replenished through carbon cycle in the atmosphere.

● Carbon cyle is the process in which carbon travels from the atmosphere into the organism and the Earth and then back into the atmosphere.

● Plants take carbon dioxide form the air and use it to make food.

● Animals then eat the food and carbon is stored in their bodies or released as CO2 through respiration. Thus carbon that was taken from the atmosphere as carbon dioxide by plants is returned back into the atmosphere by animals.

the possible dangers of global warming are-

● Due to global warming, the level of the sea will rise which will lead to flooding and this will in turn create havoc in human life.

● As the temperature becomes warmer, it can affect the health of humans and the diseases they are exposed to.

● With the increase in the rainfall water borne diseases are likely to spread like malaria. The earth will become warmer and as a result heat waves are likely to increase that can cause a major blow to the people.

● Plants will find it harder to survive when temperature increases and will die. Plants are the major source of food for human beings and as a result food shortage may occur.

Ozone layer is a layer that protects earth from the harmful ultraviolet radiations coming from the sun therby protecting us from serious ailments like cataracts, immunosuppression and thus acting as a shield. Therefore it is called as ozone umbrella/shield.

Widening of ozone hole will make the earth surface more prone to Ultraviolet radiations coming from the sun. Ultraviolet radiations are harmful radiations which cause diseases. If uv radiations will reach earth sirface, it will result in more skin cancers, cataracts and will also lower the immunity i.e. cause immunosuppression.

The process of evaporation of water and falling on the land as rain and later flowing back into the sea via rivers is known as the water-cycle.
WATER CYCLE-Water in the atmosphere is converted into water vapor by the heat from sunlight i.e. water evaporates and turns into water vapour. Also, water vapour is present in the atmosphere from plants by transpiration from leaves. This water vapour condenses in the atmosphere and forms cloud. When enough water vapour has condensed, it falls down on earth in the form of rainfall. This water flows into water bodies or seeps underground.

(i) NITROGEN CYCLE-

(ii) CARBON CYCLE-

The types of bacteria that are involved in nitrogen cycle are Nitrosomonas, Nitrobacter, Rhizobium, Azotobacter, Species of Clostridium and Pseudomonas.

Natural resources can be classified as renewable and non- renewable

Air is called the breath of life because it contains oxgen and carbon dioxide which is necessary to sustain life.

Functions of air in atmosphere is as follows-

● Carbon dioxide is used by plants to produce food and release oxygen.

● Oxygen is breathed in by human beings and animals to sustain life.

● Air is used in the process of combustion.

● The atmosphere traps the heat and keeps us warm thus ensuring that the temperature does not exceed more than normal during night and day.

Air pollution may be caused by burning of fossil fuels like coal and petroleum that release nitrogen and sulphur. These nitrogen and sulphur molecules form oxides of nitrogen and sulphur in air and later fall as acid rain too. Smog from combustion of fossil fuels also a cause of air pollution.

Effects of air pollution can be very lethal. When polluted air is breathed it results in allergies, cancer, bronchitis and other heart diseases.

● Bronchitis characterized by the inflammation and swelling of the air passages between nose to lungs and throat to lungs

● Immune system defects; it occurs due to constant breathing in polluted air

● Pneumonia- an infection of lungs caused by breathing a flying bacteria

● Asthma attacks because of inhaling various poisonous gases and constant suffocation owing to polluted air

Ozone layer is a layer of ozone molecules in the stratosphere. Ozone forms when single O atm reacts with oxygen molecule, i.e. O + O₂ → O₃ (ozone). Ozone layer protects the earth from harmful Ultraviolet raidations from reaching the earth’s surface.

Substances that contain chlorine and/or bromine are found to deplete ozone layer and are known as ozone depleting substances. One single atom of chlorine destroys 1000 molecules of ozone. CFC’s are the major ODS present in the atmosphere.

Ozone depletion would result in penetration of the harmful Uv radiations that will spread diseases like cataract and also lower the immunity.

Various sources of water pollution are-

● Waste from industries into water bodies pollutes the water bodies as majority of the waste is non-biodegradable.

● Sewage waste which is mostly from houses is also directed into water bodies.

● Runoff water from farms carries along with it chemicals of fertilizers and pesticides thus again polluting the water bodies.

The harmful effects of water pollution include diseases in aquatic biota as well as living organisms. Minamata disease was observed in people of Japan who consumed water polluted with mercury. Itai-Itai disease was also seen in people of japan after consuming water polluted with cadmium. Infectious agents like bacteria, viruses and protozoans cause diseases like Thyphoid, Cholera and Diarrheoa etc. Aquatic organisms die when they are exposed to polluted water because it alters their body-processes.

i) Eutrophication is a phenomenon that occurs in water bodies. Fertilizers run of from crop fields lead to accumulation of the chemicals in water bodies which results in algal blooms. These alagal blooms thus block the sunlight from penetrating into the aquatic bodies. The aquatic plants thus do not get sunlight to synthesize food and oxygen, thus causing Eutrophication.

ii) Chemicals, pesticides and heavy metals move up the food chain, get into aquatic bodies and are eaten by organisms like fishes which are in turn eaten by hawks/eagles. This process where the chemical enters the food chain and gets concentrated at each trophic level is known as Biological Magnification.

Organisms need water for the following reasons-

● Water has the ability to retain a good amount of energy with only little fluctuations in its own temperature It maintains our body temperature.

● Water also helps in washing away the toxins from our body through urine.

● Reactions taking place inside the cells occur between substances that are dissolved in water.

● Water also helps in transporting substances in dissolved form in the body.

Hence, organisms need water because it plays a major role in transporting substances and is a vital component in carrying out life processes.

The topmost layer of earth’s crust that supports life forms is known as soil. Soil decides the diversity of soil in a area. Soil is formed by Weathering of rocks by mechanical, biological and chemical processes.

● Physical/Mechanical- Breakdown of rocks into smaller pieces. The rocks get heated up during the day and it cools down during night. This expansion and contraction due to heating and cooling of rocks lead to splitting of rocks. Water might enter the rocks in the cracks made by expansion and contraction. When this water freezes, the rocks widen and thus rocks break.

● Chemical- it occurs when rocks are worn away by chemical changes like the chemicals released by lichens. These chemicals cause the rock surface to powder own which forms layers of soil

● Biological- Disintegration of rocks by activities of living organisms like plant grow in the cracks of rocks thus breaking the rocks

Soil pollution is defined as contamination of soil with toxic chemicals, pollutants, fertilizers and pesticides that make the soil unfit for plant growth and degrade its quality.

● Waste products from man made activities are full of chemicals that are not originally found in nature and lead to soil pollution. The by products from industries are contaminated and are not disposed off safely. This waste remains in the soil for a long time and make the soil unfit.

● Pesticides and fertilizers are full of chemicals that are not produced in nature and cannot be broken down. As a result, they seep into the ground and slowly reduce the fertility of the soil.

● Acid rain falls on soil and the aicds in the rain i.e. Sulphur and nitric oxides mix with the soil and dissolve the nutrients present in soil.

Soil pollution can lead to various harmful effects-

● Crops and plants grown on polluted soil absorb the chemicals from the polluted soil and then pass these on to us which can result in terminal diseases and also affect the genetic makeup of the body.

● The fertility of the slowly diminishes, making land unsuitable for agriculture.

● Soil pollution causes large tracts of land to become hazardous to health.

● Soil yield is also decreased due to decrease in soil fetility.

● Toxic chemicals emiited from polluted soil in landfills causes health problems.

Soil erosion is the wear of top fertile soil by wind or water is known as soil erosion.

Causes of soil erosion-

● Top soil is blown away by high speed wind.

● Deforested land losens the soil as the roots that hold the soil together no longer exist. This loosened soil gets eroded away by wind and water easily.

● Top soil is often carried away by flowing rainwater.

Effects of soil erosion are-

● Reduction in growth of new plants as the topsoil erodes away and the remaining soil is not that fertile to support growth.

● Soil erosion leads to contamination of water sources and pollutes the public areas.

Methods to prevent soil erosion are-

● Stopping deforestation and planting more and more trees so that roots bind to the soil and hold the soil together, thus preventing it from being eroded away.

●Making windbreakers from trees on the land to prevent erosion of soil by wind blowing across it.

NITROGEN CYCLE- It is a process by which nitrogen is converted into various chemical forms and is made available to living organisms.

There are various steps in a nitrogen cycle. Nitrogen fixation takes place by the action of microbes, inert nitrogen breaks down in the air and combines with oxygen to form nitrous oxide. Nitrifying bacterias in the soil take up this atmospheric nitrogen and make it available for plants. Plants get this nitrogen. Later when they decay, the nitrogen is returned back into the environment. In the soil there are some denitrifying bacterias too, they break down nitrate and release nitrogen into the atmosphere thus they end the nitrogen cycle.

Decomposers play a vital role as they breakdown the organic components of dead and decaying matter into simpler substances. The organic matter is recycled in the ecosystem thus acting as cleansing agent for the environment. Also, they return back the mineral elements into the soil to be re-used by plants for growth which helps in maintaining the fertility of soil.

Nitrifying bacteria break down ammonia in soil to nitrates which act as fertilizer to the soil. The ammonia in soil comes from decomposition of dead plants and animals.

●It recycles vital ecosystem components back to the environment for further use.

● Nutrient cycles link living and non living organisms together. This is essential because all organisms depend on one another and is necessary for the survival of living organisms. These organisms are linked by the flow of nutrients.

● Nutrient cycles facilitate the storage of elements. Elements that are carried through the nutrient cycles are stored in their natural reservoirs and are released to organisms in small amounts that are consumable.

Water in the atmosphere is converted into water vapor by the heat from sunlight i.e. water evaporates and turns into water vapour. Also, water vapour is present in the atmosphere from plants by transpiration from leaves. This water vapour condenses in the atmosphere and forms cloud. When enough water vapour has condensed, it falls down on earth in the form of rainfall. This water either seeps underground or flows into sea, rivers or lakes from where it had originally evaporated. This is water cycle.

Carbon dioxide

Atmosphere of Mars is composed of 95.32% CO₂, 2.7% Nitrogen, 1.6% Argon, 0.13% Oxygen and 0.8% carbon monoxide.

Nitrogen

Atmosphere of earth is 78% nitrogen, 21% oxygen, 0.9% argon and 0.3% carbon dioxide.

110 degree

It is 110degree at day and minus 170 at night. Moon doesn’t have an atmosphere & water vapour to diminish sun at day and retain heat at night. So either moon has 100% solar energy or completely lacks it.

Fluorine

Chlorofluorocarbons are organic compounds that have carbon, fluorine and chlorine.

humus

Humus is organic due to large content of organic carbon. It retains moisture in the soil and loosens the soil thus allowing water and air to penetrate deep underground thus increasing the soil organisms which provide nutrients to the plant.

Detritivores

Paedogenesis is decomposition by bacteria and fungi during which organic material is broken leading to humification and mineraliation. Earthworm is a detritivore that consumes organic matter and add excretory nitrogen to soil.

a) Carbon dioxide iii) GHG (greenhouse gas)

Carbon dioxide is a gas molecule with three atoms. They capture outgoing infrared energy from the earth, thereby warming the planet.

b) Nitrogen fixation i) Bacteria

Soil bacteria perform nitrogen fixation by converting atmospheric nitrogen N₂ into ammonia NH_3. This ammonia is used by plants to synthesize proteins.

c) CFCs (chlorofluorocarbons) ii) ODS (Ozone depletion substances)

Chlorofluorcarbons are compounds that contain chlorine. One chlorine atom destroys 100,000 ozone molecules when it combines with bromine in the atmosphere. Hence, chloring containing compounds are ozone depleting subtances.

d) Decomposers v) Mineralization

Decomposers (Soil microorganisms) convert organic substances into inorganic substances by mineralization.

e) Oxides of nitrogen and sulphur iv) Fossil fuels

Fossil fuels when burned, release oxides of nitrogen into the atmosphere. Many fossil fuels also contain sulphur impurities, when these are burned the sulphur is oxidised to form sulphur oxide.

a) Mercury Water pollution Minamata

Mercury was dumped into the minamata bay along with other waste products. Mercury constantly polluted the water of minamata bay. People who consumed this mercury contaminated water, suffered from disease, known as Minamata disease.

b) Paedogenesis Sun, water and wind Living organism

Sun water and wind are the physical forces that break bigger rocks into fine smaller mineral particles and lead to weathering of soil. Living microorganisms like bacteria and fungi break down organic materials and lead to humification and mineralization in the soil. This decomposition process is paedogenesis.

c) Abiotic Air and water Soil

Abiotic factors are non living components of the environment that have a strong influence on living components of the environment. Air, water and soil, these all are abiotic components of environment.

d) Carbon dioxide Photosynthesis Shell (animals)

Photosynthesis is a process wherein plants prepare their own food by using carbon dioxide, water, sunlight and chlorophyll. They release oxygen and food as by-products. Carbon from carbon dioxide dissolves in seawater and combines with calcium to form shells of calcium carbonate CaCO_3.

e) Food Resource Energy

Food is obtained from plants that synthesize it by the process of photosynthesis. All living organisms need food to sustain life because it provides energy. So, Food is a resource that provides energy to living organisms.

Pollutant Pollution

(a) Eutrophication causing chemicals → Water W

Eutrophication is a phenomenon that occurs in water bodies and results in algal blooms.

(b) SOM →Soil S

Soil organic matter is the organic matter component of soil consisting of plant and animal residues

(c) Fly ash →Air A

Fly ash is produced by the burning of powdered coal or other materials and carried into the air.

(d) ODS →Air A

Ozone depleting substances ODS are substances that contain chlorine and/or bromine atom which destroy ozone molecules.

1) Sewage treatment- Water B

Sewage is the usually the waste in form of faeces brought by municipal pipes into the water bodies. That water is further treated by various processes and sent to households.

2) Terracing- Soil A

Terracing is practised to prevent erosion of soil by wind and water.

3) Pollution under control certificate- Air C

These are certificates that are issed if a vehicle is found adding to pollution levels.

4) Vegetation Cover- Soil A

Vegetation Cover refers to assembly of plants on soil.

Environment is defined as surroundings where animals, plants and human beings function.

All the living organisms on the planet constitute the biosphere. The physical divisons of biosphere are the abiotic factors like air, soil, water, heat and light energy from the sun.

The resources available on earth like air, water, food, shelter and energy from sun are major basic requirements to sustain life on earth.

Natural resources are raw materials or substances that are found naturally in nature and have no interference of mankind. These resources are benefical to mankind.

They are of 2 types.

● Renewable resources are those that can be regenerated, replaced, recovered and are constantly available. Eg- water, wind and sun are renewable resources.

● Non-renewable resources are those that cannot be replenished once exhausted.

Eg- minerals and fossil fuels are non-renewable resources.

The atmosphere is a division of 3 spheres of earth, Lithosphere, hydrosphere and atmosphere. Atmosphere surrounds the earth and provides conditions that allow life to sustain on earth.

There are 4 major divisions of atmosphere- Stratosphere, Troposphere, Mesosphere and Thermosphere.

Unequal heating of landmass and water bodies by sun’s heat generate air movement and as a result wind blows. When the air around landmass gets heated, it becomes lighter and rises up creating a region of low pressure. Air from high pressure region escapes to the low pressure region thus generating wind currents.

Unequal heating of landmasses causes the warm/heated air to rise up. As the warm air rises up it expands and cools down. Warm air can hold water vapour well but cool air is incapable of holding water vapour. So the water vapour condenses on the dust particles already present in air and a tiny droplet is formed around the dust particles thus forming clouds.

Clouds are formed in the earth’s Troposphere where weather phenomenon occurs.

● An increase in content of harmful substances like oxides of nitrogen and suphur from fossil fuels, hydrocarbons, etc in air is called air pollution. Basically, icrease of any unwanted substance in the air is air pollution.

● Air pollution may be caused by burning of fossil fuels like coal and petroleum that release nitrogen and sulphur. These nitrogen and sulphur molecules form oxides of nitrogen and sulphur in air and later fall as acid rain too. Smog from combustion of fossil fuels also a cause of air pollution.

● Effects of air pollution can be very lethal. When polluted air is breathed it results in allergies, cancer, bronchitis and other heart diseases.

We know water is a universal solvent. Reactions taking place inside the cells occur between substances that are dissolved in water. Water also helps in transporting substances in dissolved form in the body. Hence, water plays a major role in transporting substances and is a vital component in carrying out life processes.

Various methods of rain water harvesting are as follows

● Surface runoff harvesting- Rainwater that flows off from surface is collected and used to recharge aquifers.

● Roof top rainwater harvesting- Roof acts as a catchment where the rainwater is collected. This collected water is stored in a tank or diverted to artificial recharge system.

Methods

1) Terrace, courtyard, paved or unpaved ground acts as catchment that receive rainfall directly. This rainwater is carried down through UV resistant water pipes or drains to a storage system. The water that is received in the first shower is flushed off to avoid contamination from the roof/ atmosphere. Then, filters are used for treatment of water to remove turbidity, color and microorganisms. The filters are very importan in keeping the rainwater in the storage tank.

2) Another method involves collecting the water from roof of a building and diverting it to a storage tank. Water from the storage tank can be used for secondary purposes such as washing and gardening. It is the most effective way of rainwater harvesting.

3) Ground water aquifers can be recharged by various kinds od structures to ensure that the water percolates in the ground. Recharge pits, trenches, sak ways, percolation tanks, recharging of bore and dug wells are some of the common recharging methods.

Contamination of water bodies with undesirable substances like fertilizers, pesticides or poisonous substances, thus degrading the water quality and making it unfit for drinking and other purposes is defined as water pollution.

Water pollution occurs from organic pollutants like detergents that are a part of domestic waste, insecticides from farm runoff. Inorganic water pollutants include heavy metals, fertilizers, chemical wastes from industries. Industrial waste into water bodies pollutes the water bodies as majority of the waste is non-biodegradable. Industries also use water for cooling in various operations and later return this hot water to water-bodies therby causing thermal pollution. Sewage waste which is mostly from houses is also dumped into rivers or lakes. Runoff water from farms carries along with it chemicals of fertilizers and pesticides thus again polluting the water bodies.

The topmost layer of earth’s crust that supports life forms is known as soil. Soil decides the diversity of soil in a area.

Soil is composed of 45% minerals, 25% water, 25% air and 5% organic matter. Soil contains small particles or rocks of different sizes, bits of decayed living organisms and various forms of microscopic life.

Various functions of soil are-

● It is a habitat to microorgansims like earthworms.

● Soil provides water and minerals to plants to help them grow.

● Apart from these, soil is used in construction purposes.

● Soil is necessary to grow plants and crops.

Soil formation in nature takes place by weathering of rocks by mechanical, chemical and biological methods.

● Physical/Mechanical- Breakdown of rocks into smaller pieces. The rocks get heated up during the day and it cools down during night. This expansion and contraction due to heating and cooling of rocks lead to splitting of rocks. Water might enter the rocks in the cracks made by expansion and contraction. When this water freezes, the rocks widen and thus rocks break.

● Chemical- it occurs when rocks are worn away by chemical changes like the chemicals released by lichens. These chemicals cause the rock surface to powder own which forms layers of soil

● Biological- Disintegration of rocks by activities of living organisms like plant grow in the cracks of rocks thus breaking the rocks

Soil erosion is the wear of top fertile soil by wind or water is known as soil erosion.

Causes of soil erosion-

● Top soil is blown away by high speed wind.

● Deforested land losens the soil as the roots that hold the soil together no longer exist. This loosened soil gets eroded away by wind and water easily.

● Top soil is often carried away by flowing rainwater.

Some methods to prevent soil erosion are-

● Stopping deforestation and planting more and more trees so that roots bind to the soil and hold the soil together, thus preventing it from being eroded away.

● Making windbreakers from trees on the land to prevent erosion of soil by wind blowing across it.

The process of evaporation of water and falling on the land as rain and later flowing back into the sea via rivers is known as the water-cycle.
WATER CYCLE-Water in the atmosphere is converted into water vapor by the heat from sunlight i.e. water evaporates and turns into water vapour. Also, water vapour is present in the atmosphere from plants by transpiration from leaves. This water vapour condenses in the atmosphere and forms cloud. When enough water vapour has condensed, it falls down on earth in the form of rainfall. This water flows into water bodies or seeps underground.

The conversion of atmospheric nitrogen into ammonia NH3 is known as nitrogen fixation. Bacteria that perform nitrogen fixation are either free living or they may form symbiotic associations with other organisms.

NITROGEN CYCLE- It is a process by which nitrogen is converted into various chemical forms and is made available to living organisms.

There are various steps in a nitrogen cycle. Nitrogen fixation takes place by the action of microbes, inert nitrogen breaks down in the air and combines with oxygen to form nitrous oxide. Nitrifying bacterias in the soil take up this atmospheric nitrogen and make it available for plants. Plants get this nitrogen. Later when they decay, the nitrogen is returned back into the environment. In the soil there are some denitrifying bacterias too, they break down nitrate and release nitrogen into the atmosphere thus they end the nitrogen cycle.

A biogeochemical cycle is a pathway by which essential chemical substances move through the biotic and abiotic components of Earth. Nitrogen, oxygen, phosphorous, Sulphur, water cycles are some important biogeochemical cycles.

CARBON CYCLE- The carbon cyle is the process in which carbon travels from the atmosphere into the organism and the Earth and then back into the atmosphere. Plants take carbon dioxide form the air and use it to make food. Animals then eat the food and carbon is stored in their bodies or released as CO2 through respiration.

Ozone shield or ozone layer is a layer that protects earth from the harmful ultraviolet radiations coming from the sun therby protecting us from serious ailments and thus acting as a shield. Ozone molecules form when a single O atm reacts with oxygen O2 molecule.

Chlorine containing compounds are major reason for the corrosion of ozone layer. Chlorofluorocarbons and certain other ozone depleting substances that contain chlorine and/or bromine are responsible for depletion of ozone layer. CFCs are made of chlorine. One single atom of chlorine destroys 1000 molecules of ozone.

The harmful effects of ozone depletion are-

a) More skin cancer in humans due to ultraviolet radiations which will easily reach the skin cells through stratosphere if ozone layer depletes.

b) UV radiations would also damage parts of eyes thus causing cataracts, blindness and other diseases.

c) Immunosuppression. UV radiations could damage the immune system.

Lithosphere is the upper part of the earth consisting f crust and solid part of mantle. It contains rocks, minerals and soil.

Air contains 78% nitrogen, 21% oxygen, 0.004% of carbon dioxide and small percentage of other gases. Amount of water vapour in the air varies with temperature. At 30 degree Celsius, air can contain 4% of water vapour, whereas at -40 degree Celsius, air cannot hold more than 0.2% water vapour.

Solar energy is a renewable form of energy that cannot be exhausted ever. Radiations from sun are solar radiation so they are too inexhaustible and sustainable form of energy. Fossil fuels, minerals and soil are non-renewable sources. Once lost, they cannot be replenished.

Clouds form when water condenses in the sky. They are formed in troposphere because nearly all of the water vapour and dust particles in atmosphere are in the troposphere.

Ozone layer or ozonosphere occurs in the stratosphere. It is generally lowest at the equator and highest in polar regions. It is present to a height of 23-25kms over the equator.

Arid zone is characterized by areas of low rainfall and desert. Rajasthan and Gujarat fall in this zone.

Suspended Particulate Matter (SPM)are finely divided matter particles that cause aur pollution. They may be dispersed into air by combustion or industrial processes. Dust, soot and smoke, flyash are all Suspended Particulate Matter.

Peroxyacytyl nitrate is a part of smog that causes air pollution. It is a secondary pollutant because they are formed in the atmosphere after the emission of primary pollutants. PAN is formed when oxidized volatile organi compounds combine with nitrogen oxide.

Photochemical smog is formed in atmosphere when ozidized volatile organic compounds react with nitrogen oxide.

Water pollution occurs from organic pollutants like detergents, , insecticides. Inorganic water pollutants include heavy metals, fertilizers, chemical wastes from industries. Bacteria, viruses and fungi that contaminate water are biological causes.

Fertilizers run of from crop fields lead to accumulation of the chemicals in water bodies which results in algal blooms. These alagal blooms thus block the sunlight from penetrating into the aquatic bodies. The aquatic plants thus do not get sunlight to synthesize food and oxygen, thus causing Eutrophication.

Cadmium poisoning in drinking water of Japan from a river basin resulted in itai-itai disease in people of Japan. The symptoms included kidney disorders, anemia, pain and bone fractures.

Percolation tanks and wells are made to percolate the surface water so that it reacharges ground water level which supples drinking water.

Aeolian soil are wind deposited sand and silt sized particles. They have no coarse fragments.

Loamy soil contains a small amount of orgaic material hence it is best suited for plant growth.

Sun’s energy heats up rocks to a high temperature which causes them to expand. When temperature falls, these rock contract. This continuous expansion and contraction causes the rock layer to wear off. And hence results in weathering of rocks.

Lichens and mosses release chemicals on rocks that cause them to powder down and form layers of soil. Roots of plants in the cracks of rock cause the rock to expand and break.

Wind breaks are rows of trees and shrubs on land to prevent erosion of soil by high speed wind.

Eutrophication is a phenomenon that occurs in water bodies. Excess of nutrients result in algal blooms which stops the penetration of light into the water body and the aquatic plants are thus unable to perfrom photosynthesis.

Mercury contaminated water in Japan lead to the outspread of Minamata disease when people consumed this water polluted with high levels of mercury.

Green plants are the producers as they produce their own food by photosynthesis.

Biotic components refer to all the living components. Prodcers, consumers and decomposer, all are living components in an ecosystem.

Carbon dioxide traps infrared rays and prevent them from escaping the earth’s surface therby increasing the temperature of earth and resulting in global warming.

Greenhouse gases trap infrared rays and stop them from escaping the earth’s surface thus causing global warming.

Very low winter temperatures in the Antarctic stratosphere leads to appearance of ozone hole over Antarctica due to formation of polar stratospheric clouds.

Soil erosion is defined as blowing away of land surface i.e. soil by wind or water.

● Use of refrigerators by humans is one such activity. Refrigerators use chlorofluorocarbons (CFCs). These CFCs have chlorine molecule that have the capability to destroy ozone molecules.

● Emission of halogen source gas like bromine from human activities cause depletion of ozone in stratosphere.

● Air conditioners too use chlorofluorocarbons. CFCs are ozone depleting substances. When they are emitted from air conditioners they adeplete ozone layer.

Carbon dioxide and methane are two greenhouse gases that are causing global warming by trapping the infrared rays and thus increasing the temperature of earth.

Conversion of organic nitrogen to ammonia is called as ammonification.

Troposphere/lower atmosphere is the region of atmosphere where most of the atmospheric gases are present. It is this region where most of the weather phenomenons take place.

When increased organic waste enters the water bodies it serves as a food to microorganisms, therby increasing the number of these microorganisms in the water bodies which need more and more dissolved oxygen to utilize for their metabolism. This results in an increase in the biological oxygen demand in water body.

Biological magnification is the phenomenon where certain pollutants get accumulated in tissues in increasing concentration along the food chain. It is a process where chemicals or pesticides enter the plants through soil and are passed on through the food chain. Highest amount of chemicals get accumulated in the organism at top of a food chain.

● Soil is thr major resource require for plant to grow and produce food.

● Without soil no plants will exist and animals will die due to starvation.

● Soil holds the plants and prevents them from being eroded by environmental calamities.

● Soil is a habitat to many insects and microorganisms.

When water laden air cools down it causes water to return back to its liquid state and fall on earth in the form of rainfall. So, the chief source of precipitation is water laden air.

Rainwater is collected and stored into reservoirs before the rain water is lost through runoff process. This process is known as rainwater harvesting.

(a) Cholera, typhoid and diarrhea are diseases caused by drinking water polluted with infectious agents like bactetria, viruses and protozoans.

(b) Cancer, arsenicosis and fluorosis are diseases caused by drinking water polluted with toxic chemicals like MTBE, arsenic and fluoride.

1) Asbestosis occurs due to inhalation of asbestos dust that is used in making ceilings. Asbestos is also a cancer causing agent.

2) Silicosis occurs due to inhalation of free silica SiO₂ while working in ceramic industries.

3) Byssinosis caused by inhalation of cotton fibres, is a respiratory disease wherein pulmonary ways narrow resulting in bronchitis.

Compounds having chlorine and/or bromine are found to destroy ozone layer. One chlorine molecule destroys 1000 molecules of ozone.

If nitrogen fixation does not take place it will disturb the nitrogen cycle.

Plants will not grow if all the nitrogen from the soil is exhausted as they will not get nitrogen from the soil to grow thus creating a barren landscap.Entire food chain will be disturbed as herbivores will not have plants to eat so they will die and in turn carnivores will die because they wont have any herbivores to feed on. If all the carnivores will die in an ecosystem, humans will also not get food, neither products from plants nor food from animal flesh.

Life is not possible on Mars and Venus because these planets have 95-97% of carbon dioxide and no oxygen to sustain life.

Chemicals from industries, sewage waste i.e. mostly domestic waste and farm runoff (fertilizers/pesticides) are all released ultimately into some water body. The chemicals in these waste are usually harmful and they pollute the water bodies.

Lead compounds are added to petrol so that petrol burns smoothly in vehicles. The harmful effect of these lead compounds in petrol is that toxic lead compounds are released through the silencer/ exhaust pipes of vehicles. Inhalation of these compounds causes diseases like brain damage, anaemia etc.

Itai-itai

Itai-itai is one of the biggest pollution disease that occurred in people of Japan from drinking water polluted with cadmium.

True

When warm air (heating by solar radiations) from land rises up, the cold air escapes downwards. This movement of warm and cold air generates wind.

Fertilizers like phosphates, phosphorous and nitrogen result in algal growth in water bodies.
Eutrophication is a phenomenon wherein excess of nutrients, chemicals in water body result in algal growth which stops the sunlight from reaching to the aquatic plants due to which plants do not produce oxygen and the aquatic animals die due to lack of it. Thus, eutrophication reduces the oxygen content (biological oxygen demand increases) due to which life forms are affected and they die. Water quality is drastically reduced as the toxicity is increased.

1) GHG (c) Global Warming

A greenhouse gas is a gas that traps infrared rays and prevents heat from escaping the earth, thus causing global warming.

2) CFCs (b) Methane

A chlorofluorocarbon is a organic compound that is a volatile derivative of methane, ethane and propane.

3) PAN (d) Smog

Peroxyacyl nitrate is a type of air pollution that is part of photochemical smog. Basically PAN’s are respiratory and eye irritants.

4) Lichen (a) Paedogenesis

Lichens grow on rock surface and bring about biological weathering of rocks. While they grow they release some substances that cause rock suface to powder form a thin layer of soil. Paedogenesis is the final step in soil formation where bacteria and fungi decompose organic matter leading to humification.

The atmosphere on Venus is primarily composed of 97% carbon dioxide which is denser and hotter than that at earth. Mars too, is composed of 95% carbon dioxide.

All the elements of life support system are inter-related, inter-dependent, inter-connected. Food chain and food web are clear examples of this.

Bacteria and fungi are microorganisms that decompose the dead and decaying matter.

Water flowing through through dams spin the turbine plates to generate electricity. There is no air or water pollution caused by hydroelectric power plant.

Biosphere constitutes all the living beings and their relationships along with their interaction with lithosphere, hydrosphere and atmosphere.

Air is inexhaustible resource. It is present in an abundant amount and will not ever run out or deplete.

Moon doesn’t have an atmosphere & water vapour to diminish sun at day or retain heat at night so moon experiences different temperature at day and night.

Only 2.5 percent of total water is found as fresh water which occurs in lakes and rivers.

Paper industry uses fuels and buring of fuels like coal releases mercury that is a toxic chemical.

Fertilizers contain chemicals. High amount of fertilizers leads to increased amounts of chemicals which kill the microroganisms that recycle nutrients which also degrades the soil structure. Fertilizers in soil when transported or carried off by water into water bodies, result in algal blooms in aquatic bodies thus causing eutrophication.

Winds transport the rocks. During the transport abrasion occurs i.e. the rocks are scraped off as a result of friction between the rocks and sediment particles.

Forest destruction results in all of the above mentioned effects.

● Animals lose their habitat when forests are cut down

● The soil losens when trees are cut down as roots of the trees no longer exist to hold the soil which hence results in floods and soile erosion by wind and water.

Green plants are producers in an ecosystem i.e. they produce food. The food obtained from plants is utilized by all the other components of an ecosystem. Hence, Green plants are ultimate source of energy.

Suphur dioxide is a gas that dissolves in water and produces acidic ions that are highly reactive. When lichen absorb this gas, it disrupts photosynthesis, inhibits reproduction and other activities.

Eutrophication leads to algal blooms in water bodies thus blocking the penetration of sunlight in the water bodies. Hence the plants do not get sufficient sunlight to carry out photosynthesis hence oxygen is not produced.

Nitrosomonas and Nitrobacter are bacteria that carry out nitrification.

Nitrosomonas oxidize ammonia into nitrite. Nitrobacter break down nitrite into nitrate.

Rhizobium is a gram –ve bacteria that fixes nitrogen. Nif gene occurs in Rhizobium.

Waste from industries into water bodies pollutes the water bodies as majority of the waste is non-biodegradable. Sewage waste which is mostly from houses is also directed into water bodies. Runoff water from farms carries along with it chemicals of fertilizers and pesticides thus again polluting the water bodies.

Greenhouse effect is caused by infrared rays. Gases like carbon dioxide absorb infrared rays, therby increasing the temperature of earth and hence causing greenhouse effect.

This is because its molecules are not in direct contact with one another. Heat conduction occurs best through substances whose molecules are in contact with one another. So air is a bad conductor of heat.

Greenhouse is related to global warming. Greenhouse gases absorb infrared radiations and stop it from escaping the earth’s surface which results in increase in temperature of earth, thus causing global warming.

Burning of fossil fuels like coal, natural gas and oil for fulfilling various needs is a major source of air pollution. The gases that are released on the burning of these compounds results in air pollution.

Lichens are sensitive to Sulphur dioxide because they have efficient absorption systems due to which they rapidly accumulate Sulphur from high levels of Sulphur dioxide in air.

Soil is a thin layer of sediments and fine particles covering the earth’s surface. It is mainly formed from weathering of rocks by various processes.

Land absorbs more heat because they are darker, hence heat up faster than water bodies by absorbing solar radiations. Water bodies on the other hand reflect most of the solar radiation that fall on it thus not getting heated faster.

Winds erode away lose soil, heavy rains also wash away soil that is loosely bound. If the fields are left fallow for long , since there will be no plants to hold the soil the soil easily gets eroded away by wind and water.

Terrace farming and intensive cropping, both are helpful in preventing soil erosion. Terrace reduces the speed of water moving across the soil surface which reduces soil erosion. Also, Terrace farming allows more intensive cropping which thus binds the soil and prevents soil erosion.

Carbon dioxide traps the infrared rays and prevent heat from escaping the earth’s atmosphere. This causes the qwtemperature of earth to rise which is known as global waring.

Denitrification is the removal of nitrogen or nitrogen compounds. The conversion of NO3 into N2 is denitrification.

Nitrosomonas are rod shaped bacteria that oxidize ammonia into nitrite . Nitrosomonas are useful in bioremediation.

Ozone layer blocks the UV radiations coming from sun and thus preventing organisms on earth from various diseases like cataract and preventing the immune system from weakening.

Methane, carbon dioxide and chlorofluorocarbons; all of them are greenhouse gases that trap the infrared rays and thus trap the heat, not allowing it to escape the earth’s surface, hence contributing to greenhouse effect.

Rajendra Singh is popularly known as water man of India. He is a water conservationist from Alwar, Rajasthan.

Chlorofluorocarbons are inorganic compounds that contain only carbon. They are widely used in refrigerators, aerosol propellants and formation of foam.

Ozone hole was discovered in 1985 over Antarctic by Joe Farman, Brian Gardiner and Jonathan Shanklin.