Sunday 25 August 2019

FST -1

11th Part

Q.  Mention the role of biotechnology in the field of agriculture.   

A.  Due to biotechnology certain favorable changes have been introduced in agriculture by scientists. Some of the examples of biotechnology are the high Yields seeds, resistance to diseases, improved nutritional quality, and adaptation to adverse environmental conditions. An important aspect in the production of improved plants is the breeding process. This enables one to combine, one or more, favorable quality of the parents to be passed on to their progeny. For this purpose, scientists use several methods for raising the plants. The most common methods are:-
(i) the traditional method, in which seeds and root stocks have been used as basic materials for raising plants,
(ii) the other method is the use of plant cells as any plant cell can give rise to a complete plant. These methods are useful not only for the improvement of present-day crops, but also for the creation of novel plants and new crops, which are of short duration, high-yielding-type, and resistant to diseases and other adverse environmental conditions.


Q.  Mention the names of two diseases caused due to protein-calorie malnutrition. State their symptoms.                         

A.  Two severe diseases which are caused due to the deficiency of proteins and protein-calorie are Kwashiorkor and Marasmus, respectively. Millions of children die annually and millions more go through a miserable life because of these diseases. They retard the child's physical growth and weaken its natural immunity to various infections. In extreme cases, children are mentally retarded and they never reach maturity and thus become a burden to the family and the nation.
Symptoms of Kwashiorkor - The symptoms of kwashiorkor include: change in the skin and hair colour (to a rust colour) and texture, fatigue, diarrhoea, loss of muscle mass. failure to grow or gain weight, edema (swelling) of the ankles, feet, and belly. It also leads to the damaged immune system, which can lead to more frequent and severe infections. Hence the child is exposed to diseases. Due to low energy food and protein intake, the child gradually loses the appetite and often develops weaning diarrhoea.


Symptoms of Marasmus - Thin face, Ribs, and shoulders clearly visible through the skin. Very loose skin that sometimes hangs in folds in the upper arms, thighs, and buttocks. Persistent dizziness, Sunken eyes, Diarrhoea, Active, alert, or irritable behaviour, and Frequent dehydration. This is manifested by severe retardation in growth, loss of muscles and subcutaneous fat.



Q.  Why is soil considered a basic resource for agriculture? How can saline and alkaline soils be reclaimed?                     

A. Nature takes more than 50 years to build a centimeter of top soil. But every year, wind, water & human neglect, cause worldwide erosion of over 6,000 million tonnes of soil, along with 2.6 million tonnes each of nutrients like nitrogen and potassium, and 3.3 million tonnes of phosphorus. Though history has taught us that civilizations have vanished because of improper use of soil, still we are diverting millions of tonnes of excellent soil for brick-making and road laying. This wasteful practice should be drastically curtailed by making use of alternative and more durable materials for making bricks and roads. Today, our agricultural land is less than 0.33 hectares to a person, which is below the prescribed limit. It is time we created a country-wide awareness of the value of soil and the importance of scientific land use. We must understand that, if we neglect our soils, our future will be in peril.
             Saline and alkaline soils are the result of centuries of neglect and mismanagement of our soils. About 7 million hectares of land is thus affected. These unproductive soils cover about 2.5 million hectares in arid Rajasthan and Gujarat, 1.4 million hectares in the black-soil region, and 2.1 million hectares in the coastal regions. Alkaline soils contain high amounts of carbonates and bicarbonates of sodium. Saline soils contain chlorides and sulphates of sodium, calcium, and magnesium. In both the above types of soils, salts are present in quantities large enough to interfere with crop growth.
             It is now possible to reclaim alkaline soils with the cultivation of fodder grasses like Brachiaria mutica (Para ghas), Panicum antidotale (Neelon ghas) and Cynodon dactylon (Doob), and tree species like Prosopis chilensis (Vilayati khejri), Acacia nilotica (Kikar) and hybrid Eucalyprus. The trees establish quickly when planted in small holes filled with manure to which a little gypsum is added. In the very first year after reclamation with grasses, this soil can be used for planting other crops. Here, special varieties of rice can be grown as Kharif, and wheat as rabi crop. 
             The crucial factor in the management of saline soils is drainage. Saline soils have a high water-table. Drainage channels one meter deep and 30 meters apart effectively bring down the water table and help in reducing soil salinity. In the soils reclaimed in the above manner, sorghum, maize, and wheat which can tolerate salinity of soil can profitably be raised.


Q.  What is Biotechnology? Describe the underlying techniques of genetic engineering and enzyme immobilization.           

A.  Biotechnology is a branch of science which deals with the use of biological systems, organisms to produce products on a large industrial scale. Due to biotechnology certain favorable changes have been introduced in agriculture by scientists. Some of the examples of biotechnology are the high Yields seeds, resistance to diseases, improved nutritional quality, and adaptation to adverse environmental conditions. An important aspect in the production of improved plants is the breeding process. This enables one to combine, one or more, favorable quality of the parents to be passed on to their progeny. For this purpose, scientists use several methods for raising the plants. The most common methods are:-
(i) the traditional method, in which seeds and root stocks have been used as basic materials for raising plants, 
(ii) the other method is the use of plant cells as any favorable plant cell can give rise to a complete plant. These methods are useful not only for the improvement of present-day crops, but also for the creation of novel plants and new crops, which are of short duration, high-yielding-type, and resistant to diseases and other adverse environmental conditions.
Genetic Engineering - It involves the alteration of the genetic material of a particular plant, by the substitution or addition of new genetic material from some other plants. Presently, the scientists, are trying to transfer the genetic material, that enables legumes to fix nitrogen in the soil, to various economically important plants. If this is achieved, it would be a milestone in agriculture.
Tissue Culture - It makes use of the important quality of plant cells as any favorable plant cell can give rise to a complete plant. Based on this fact, any cell or a group of cells, or part of a plant such as a piece of stem, leaf, etc. can be grown on a nutrient medium under suitably controlled conditions in the laboratory. This method is commonly known as tissue culture. It enables us to get true-breeding types without going through the stages of flowering, production of seeds and their germination. This technique has great potential in our crop improvement programmes, and it has already been used in the improvement of varieties of wheat, rice, corn, and several other plants. This method is useful not only for the improvement of present-day crops, but also for the creation of novel plants and new crops, which are of short duration, high-yielding-type, and resistant to diseases and other adverse environmental conditions. 
              By applying the principles of biotechnology we can raise orchards where the fruit trees will be of desired, manageable height and form. The fruits will be of uniform size, shape, color and weight. They will have the same flavor and nutritional value and will ripen at the same time. This will make harvesting, storage, packing, transport, canning, and processing easy.  


Q.  Discuss the importance of nutrition for the health of a person. State the different nutrient groups with their respective functions.    

A.  To remain healthy and free of disease, our body requires certain kinds of food. The health of an individual is largely determined by the quality of food taken. Moreover, food makes a difference in our appearance, activity, behaviour, and in the quality of life. Foods vary in their composition and no one type of food contains all the required nutrients. A meal lacking in a particular requirement of our body for a prolonged period can result in disease, and even in death. Therefore, a knowledge of the food requirements of our body and various sources of obtaining them is essential. Studies carried out in many countries show that a good diet has promoted proper growth in children and has improved the general health of the people. Conversely, lack of diet, or diet without essential nutrients can lead to a steady decline in the physical and mental growth of these children and they suffer from various deficiency diseases.  Scientists have determined the chemical substances present in different foods and their role in the body. They call these substances "nutrients" and have classified them in different groups. These are Carbohydrates, protein, minerals, fats, water, vitamins. Their functions are -
1.  Carbohydrates and Fats are the main energy source for the body. Carbohydrates are easily available and are the cheapest source of energy. Fats also serve as an "emergency energy store" in the body, to be used, for example, when enough food is not available due to fasting or starvation. Therefore. carbohydrates and fats are called Energy Foods.
2.  Proteins are the raw material used for building muscles, skin, blood, and bones. They repair the tissues which are constantly worn out. Therefore, we need to have proteins every day. Proteins can also serve as an energy source if the energy need of the body is not met by carbohydrates and fats. They also help us to fight infection.
Proteins are called Body Building Foods.
3.  Minerals and Vitamins are not a source of energy but they are necessary in many of the steps involved in the release of energy in the cells. Thus, they help the body to make good use of food. They protect us from illness. Minerals, such as calcium, are the basic components of bones and teeth. Iron is a component of the red pigment of blood called haemoglobin. Minerals are important in the transmission of nerve impulses and for muscle contraction and relaxation. Vitamins and minerals are called Protective Foods.
4.  Water is a component of all body fluids such as blood, digestive juices, etc. Water accounts for about 50 to 70% of the body's weight. It is essential for various metabolic activities. In fact, our body cannot utilize any substance, unless it is first turned into a form soluble in water. Digestion converts food into a soluble form so that it is readily absorbed and is carried by the blood to the sites where it is needed. The waste products like urea are carried by the blood to the kidneys from where they are excreted. Water also plays a role in regulating body temperature, through perspiration. The daily water requirement of the body depends on the climate, activity and the kind of food one takes.


Q.  What is meant by a balanced diet? suggest the composition of a balanced diet needed by an adult working man.       

Q.  What is a balanced diet? Name four items in a meal which would make it a balanced meal.                                
 A Balanced diet is a combination of various foods that fulfill all the basic requirements of the body in essential nutrients. The intake of a balanced diet can fulfill the energy needs of a person and can provide proteins, vitamins, minerals, carbohydrates and fats in proper quantity and proportion. It is required to keep him healthy, active and free from any disease. 
                    Balanced Diet for Various Age Groups


Mixed cereals, Pulses, green leafy vegetables, and milk or milk products are the four important items that should be included in the meal to make it a balanced diet.


Q.  (i) "Agriculture is the bedrock of the Indian economy." Justify the statement.

(ii) Write brief comments on the basic resources for agriculture in India.   
A.  Agriculture is the bedrock of the Indian economy as of the approximately 245 million working people in India, (1981 figures) 149 million people are engrossed in the agriculture sector. About 93 million were cultivators and 56 million were agricultural laborers. Together they constituted more than 60% of the total work-force of India. To these 149 million people, agriculture is not only the main source of income but a way of life. Almost 70%of the total population resides in villages which are completely dependent on agriculture-related activities. We have a total geographic area of about 329 million hectares. The net area under cultivation is 142 million hectares, of which about 31 million hectares are cultivated more than once a year, hence the total cropped area amounts to 173 million hectares. Our farmers and agricultural laborers, who constitute 60.5% of the work-force, contribute 34.7% of our total net national product. Hence, agriculture employs a large chunk of our manpower and provides the means to earn their Livelihood. 
          There are three basic resources for agriculture, they are sunlight, soil, and water. 
Sunlight - It is the basic resource of agriculture which is used by plants for producing food during the photosynthesis process. During monsoon, the wettest season, the sky is overcast most of the time and thus the availability of sunlight is minimum. In summers, maximum sunlight is available, but unfortunately, it is the period when water availability is at its minimum. Winter, however, is the best period of the year, as there is enough of sunlight and moisture.


Soil

Soil is another important resource. Nature takes more than 50 years to build a centimeter of topsoil. Soil, which forms the uppermost layer of the land, is the most precious of all resources because it supports the whole life system on Earth. It provides food and fodder in the form of vegetation and stores water essential for life. It contains sand, silt, and clays, mixed with air and moisture. It possesses rich organic and mineral nutrients that are required for agriculture. The type of soil varies from place to place. Those soils which are rich in organic matter are fertile. Fertility is also dependent on the capacity of the soil to retain water and oxygen. There are different types of soils found in our country. Alluvial soils in the North Gangetic plains are the finest, black soils are next in productivity which are followed by red-and-yellow soils. The other kinds of soil available in our country are red soils, deltaic alluvial and Brown, laterite, desert, hill and mountain soils. Deep red soil is good for the cultivation of potatoes, bananas, pineapples, and rubber, etc. Black soil supports crops of sugarcane, groundnut, soybean, cotton, and rice, etc.


Water

Water is the third important resource in agriculture. A major problem in our country's agriculture is its dependence on rain to fulfill the requirements of water. Out of our net cultivated area of 142 million hectares, only 40 million hectares of area is covered by irrigation network. The rest is dependent on rain. In our country, which is situated in the monsoon belt of south-east Asia, the rainfall is neither uniform nor is evenly distributed throughout the year. As a result of it there are many regions in our country which get scanty rainfall resulting in agriculture failure.

Saturday 24 August 2019

FST -1

10th Part

Q.  Taking a pond as an ecosystem, write five of its biotic components and classify them as producers, consumers, and decomposers.     
A. Within an ecosystem, the organisms can be classified under three broad categories, namely, producers, consumers, and decomposers. 
Producers -
Sun is the ultimate source of energy for nearly all life on the earth. Solar energy enters life mainly through green plants, and also through some kinds of bacteria and algae which are called producers. During photosynthesis, green plants use the energy of sunlight to convert two simple, low energy substances, carbon dioxide, and water, into more complex substances, such as carbohydrates which we may call food. Photosynthesis produces oxygen as a by-product. To carry on photosynthesis and make food, green plants need not only sunlight, water, and carbon dioxide, but also small amounts of some minerals such as calcium, potassium & magnesium dissolved in the water around &he floating plants or in the soil water around plant roots.
Photosynthesis:
Carbon dioxide + water + solar energy + minerals + food + oxygen
Decomposers -
So far we have seen that green plants are called producers because they produce their own food. Plants live and die, they may be eaten up by animals who also eventually die. There are organisms - the decomposers which act on dead plants and animals and for their existence. The dead bodies of plants & animals are the principal source of food for these decomposers. The decomposers, such as bacteria, fungi, and worms, convert the dead bodies of the plants and animals back to their elementary forms.
Consumers -
Besides the producers and decomposers, there is another category of organisms - the consumers. These organisms cannot make their own food, and they depend directly or indirectly on producers, for energy and nutrients.

Q.  How do forests regulate precipitation?
A.  Forests not only add to the beauty of the landscape but make the climate salubrious and provide a suitable habitat for the wildlife. They are also described as environmental buffers. Forests consume large quantities of water through the roots of plants and lose it through respiration by the leaves. Extensive forests, to some extent also increase precipitation.

Q.  Social Forestry                          
A. Social forestry means planting trees on all unused and fallow land to meet the basic requirements of people. A farmer can partly meet his needs of wood from the fast-growing trees planted within the limits of his village, along the footpaths, roadsides, alongside railway tracks, side roads or canal,, and streams, boundaries of fields and empty spaces. The aim of social forestry is to meet the needs of fuel, fodder, fruits, timber, and other requirements. Social forestry leads to afforestation of barren and deforested lands with the purpose of helping environmental, social and rural development. Social forestry is basically for the people by the people and of the people approach. It leads to an increase in forest cover that is close to human settlement and has been degraded over the years due to human activities. The social forestry scheme was initiated in India to increase fuel availability in rural areas and to prevent soil erosion. 

Q.  Photochemical smog          
A.  Photochemical smog, a secondary Pollutant, results when the two pollutants, nitrogen oxide and hydrocarbons found in automobile exhausts, react with one another in the presence of sunlight to produce nitrogen dioxide (N02), ozone (03) and a compound called PAN (Peroxylacetyl nitrate). It forms air that appears as a yellowish-brown haze. Breathing ozone affects the respiratory and nervous system. It causes respiratory distress, affects eye membranes and stimulates tears. It also causes a headache. Ozone also damages rubber articles, textiles, and discolors paintings. It has been recently found that smog is harmful to timber. PAN is especially damaging to plants. Plants exposed to PAN exhibit leaf mottling.

Q.  Acid rain
A.  Sulphur dioxide and nitrogen oxides emanating from industrial smoke react with water in the atmosphere to give rise to sulphuric acid and nitric acids. These acids, formed in the air, come down to the Earth along with rain. The pH of acid rain depends on the concentration of sulphur dioxide and nitrogen dioxide in the atmosphere. The pH of acid rain varies from 5.6 to as low as 3.0, which makes it almost as acidic as vinegar. 
           It causes direct damage to the leaves of p!ants. Forests in many parts of the industrialized world are drying because of acid rain. It also causes the leaching of nutrients out of the soil, some of which are very essential for plant growth, e.g., calcium and magnesium. These nutrients are carried out of the soil into streams and ponds. Acid rain also affects lakes. Their waters become devoid of life, except for some algae and fungi that grow at the bottom. Acidity leads to an increase in dissolved metals, particularly aluminium. This element affects the gills of the fish. and they die of suffocation. Birds living near lakes that have high aluminium content are poisoned by aluminium because they feed on the aquatic insects. Acid rain also corrodes materials such as marble stonework and metals.

Q.  Oceans are known as the largest and thickest ecosystems. Justify this statement.                               
A. Oceans are known as the largest and thickest ecosystem. Tiny plants and animals exist in it, in immense numbers. A cubic meter of seawater may contain as many as 200,000 organisms. Living forms occur, more or less, throughout the depth of the oceans, but they are denser around the continents and islands. Sunlight is the principal source of energy in all ecosystems including Ocean. Energy is provided by sunlight either directly as in the case of plants, or indirectly to other forms of life via the plants. In oceanic waters, the intensity of light decreases rapidly with depth. Animal life is also distributed zone-wise in oceans. In the upper layers, small animals co-exist with phytoplankton and derive energy from them. A little below, the energy for animal life is obtained from wastes and dead bodies of organisms that sink, or from the living animals that swim down.
         The nutrients in the upper layers of water are constantly being taken up by the phytoplankton, who are the producers, and then these pass on to the herbivores, and the carnivores. When these latter organisms die, they are either eaten up by other animals or they get decayed by the decomposers. Some of the decomposed matter sinks to the ocean floor. It means the nutrients taken up by the producers from the upper layers of seawater are constantly being drained to the lower layers of seawater thus supporting the life.

Q.  Discuss the impact of increasing population on the environment.     
A.  The increasing population puts a strain on the resources of the world, including environmental resources. All the things we dig out of the earth such as coal, iron, petroleum, copper, and so on, are available in limited supply and all of them are going to be exhausted within a limited number of years and if the population keeps growing, world consumption of these materials will keep increasing, advancing the date of resource exhaustion.
            A larger and larger population also requires more production of food. Agriculture requires land and in many countries, the land is not available to grow the crops needed for the doubling or tripling population. There is a tremendous strain on resources of drinking water, and on facilities to remove filth and muck. The larger population could mean a shortage of housing, congestion on roads, slums going from bad to worse, and pollution. 
More population means an increase in waste in the environment. As the man-made waste is not transformed, it leads to the degradation of the environment causing pollution. Further, waste leads to air, soil and water pollution.

Increasing population forces Man to establish new housing colonies. National highways, industries, hydropower projects, etc. are built by cutting down forests. These destructive activities to meet the needs of the increasing population led to ecological imbalance.

Rapid growth of population has led to urbanization which has adversely affected the environment. Due to population pressure, natural resources in the cities are depleted at a fast rate.
intensive farming and excessive use of fertilizers and pesticides have led to over-exploitation of land and water resources. These have led to land degradation in the form of soil erosion, waterlogging and salination.
The increase in consumption of fossil fuels due to transportation also led to environmental degradation. The automobiles release huge quantities of poisonous gases such as carbon monoxide, nitrogen oxides, and hydrocarbons. The development of ports and harbors have led to oil spills from ships adversely affecting fisheries, coral reefs, mangroves, and landscapes.

Q.  What are persistent pollutants ? Give an example.        
A. The pollutants that remain in an environment in an unchanged form for a very long time period are known as persistent pollutants, e.g. pesticides, nuclear wastes, and plastics, etc. Many POPs(persistent organic pollutants) are currently or were in the past used as pesticides, solvents, pharmaceuticals, and industrial chemicals. Although some POPs arise naturally, for example during volcano eruptions they are released in the environment. The POPs are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of their persistence, POPs bioaccumulate with potential adverse impacts on human health and the environment.

Q.  Non-persistent pollutants.
A.  those that break down, into simple products, and are known as non-persistent pollutants, e.g., garbage. If this breakdown process is facilitated by living organisms, then such pollutants are referred to as biodegradable pollutants, e.g., wastes from animal sheds

Q.  Describe the ways to manage water resources. 
A. Management of water resources means 
(i) the water of the right quality is made available for all kind of Uses and 
(ii) there is no misuse or wastage of this precious resource.
Water management includes recharging the reserves of groundwater and diverting supply from an area of surplus to the region of scarcity. Recharging of groundwater is the most important aspect of water management. 
           In the mountains and hills, the watersheds are covered with vegetation. The litter-covered soil of the watershed allows the infiltration of rainwater, which finds its way to the aquifers.
    In urban and rural areas, stormwater used water or domestic drains can be fed into pits, trenches, or any depression, where water can filter down to underground reserve. The excess flow of normal, as well as floodwater, can be diverted to areas where there is a scarcity of water. By proper treatment of the domestic and municipal wastewater, one can obtain a supply fit for many industrial & agricultural purposes. The treatment of wastewater involves the removal of pollutants, germs, and toxic elements.
Desalination of seawater
By use of solar energy, seawater can be distilled, thus freshwater of good quality can be obtained. This method of desalination of seawater is being used in our country at places like Bhavanagar in Gujarat and Chum in Rajasthan.
Reducing over consumption
Using more water than necessary is an unpardonable waste of the precious and scarce resource. In our country, a lot of water is wasted due to leaking taps and bad plumming. There is also a need for a check on excessive irrigation.

Q.  What do you understand by recycling? How the recycling of wastes improves resource utilization?                 
A. Some of the materials once used do not go waste, these materials can be re-used again. The process through which the waste resources or used materials are again made usable is known as recycling.
     Scraps and used metals
Scrap metal is produced in large quantities in mills and factories. Old used metal of discarded vehicles, machine, aircrafts, ships, buildings, etc. can be melted and recycled for useful purposes. For ex. used aluminium utensils, can be collected, melted and shaped into new utensils. We can meet the ever-growing demand of such scarce metals as copper, zinc, lead, platinum, etc. by recycling the used old discarded materials.
Waste water
Domestic and municipal waste water is rich in organic nutrients. If this kind of water is treated and made free from disease-carrying germs, pollutants, and poisonous elements, it can be used for the irrigation of farms, gardens, and other vegetations.
          For the removal of germs and toxic elements, the waste water or sewage is treated in a tank or in ponds for several days. In doing so, firstly, the heavy particles settle down to the bottom by themselves, while the finer particles are made to settle down by adding alum and caustic soda. The clear liquid is then allowed to pass through filters or sand or earth and finally, the air is blown through it. This treatment not only removes carbon dioxide and hydrogen sulphide which is generally dissolved in waste water, but also adds oxygen to the filtered water, thus helping in purification. Treatment of water with appropriate doses of chlorine, known as chlorination, kills all the harmful germs and makes water usable.
Solid waste
Solid waste in some cases can be a resource. In our country, the main street of Patna city is being illuminated by biogas produced from the waste of the city dwellers. In Delhi, the sewage treatment plant produces cooking gas. Fermentation of wastes such as cattle dung, human excreta, garbage and aquatic weeds like algal, and water hyacinth, produces biogas which can be used for a variety of purposes. Slag, a waste product left when the metal has been extracted from its ore, can be powdered and added to cement for construction. Flyash is another material used as a valuable cementing material.
        It is clear from the above that the solid wastes can serve as a very useful resource for providing the raw material for our industries, for generating energy and for the production of manure.

Q.  What are the important environmental considerations that should be taken into account while implementing technology policy?     
A.  Some of the important environmental consideration are - 
The industries should have been established at safer places, away from centers of population. In addition to this, the factories must be well equipped with safety devices which would automatically minimize the chances of an accident.
# These factories shouldn’t discharge wastes directly into water bodies without treatment, as these chemical discharges contain heavy metals like mercury, lead, etc which not only destroy the marine life but also underground water thus only after treatment the industries should be allowed to discharge wastes.
# the industries should be asked to use low sulphur coal for burning or use other fuels for burning as high sulphur content destroys the environment.
# scrubbers should be used so that chimneys don’t throw toxic gases in the environment as scrubbers reduce the ash and sulphur content.

Q.  Why and how has Global warming become a serious issue?   A. The burning of fossil fuel by industry and transportation vehicles keeps adding carbon dioxide to the air and due to deforestation, CO2 can’t be removed from the atmosphere. If the amount of carbon dioxide in the air keeps on increasing, it will lead to an increase in temperature on the earth. This is because CO2 traps the heat radiation from the sun and this process is called the greenhouse effect. This will lead to an increase in the temperature of the globe and thus leads to global warming.
    Since 1958. the concentration of carbon dioxide in the atmosphere has risen by almost 6 percent and is expected to increase in the future. If the present trend continues, it is feared that a doubling of atmospheric carbon dioxide could occur sometime towards the middle of the next century, and this would cause an average annual temperature rise of 3 to 8OC. This rise in temperature could have a disastrous impact on all life. It will affect agriculture, resulting in problems in the availability of food and other agriculture-based activities. Melting of polar ice would result in the rise of sea level. This could submerge many coastal areas. It is feared that cities like London, Glasgow, Florida, Tokyo, Osaka, Montreal, Stockholm, Copenhagen, and Calcutta would lose much of their territory to the rising waters.

Q.  List any five advantages of using nuclear energy to fulfil our energy needs. 
A. # energy produced by nuclear power plant doesn’t use fossil fuels, hence it is a renewable source of energy
#  it is clean energy, that means no smoke comes out due to nuclear fission and this doesn’t pollute the environment.
# less land is required to establish a nuclear power plant.
#  Unlike coal and natural gas that are pollutants, nuclear energy does not release carbon dioxide and is cleaner. Moreover, it has lower greenhouse emissions.
#, in the long run, it is a cheap source of energy.

Q.  With the help of a suitable example, explain how a persistent pollutant gets accumulated in the organism of various trophic levels.    
Q.  What’s soil pollution
A.    Answer includes soil pollution along with above
    Soil pollution means depriving the soil of all nutrient contents making it barren or unfit for cultivation. Due to the discharge of untreated wastes, pollutants, poisonous substances, soil erosion etc soil gets polluted. Soil, which forms the uppermost layer of the land, is the most precious of all resources because it supports the whole life system on Earth. It provides food and fodder in the form of vegetation and stores water essential for life. Soil pollution is rapidly increasing in the rural, urban and industrial areas due to unscientific and irrational disposal of solid wastes generated by human beings from their domestic and industrial activities. In many rural parts of our country, daily thousands of people pollute the soil through their wastes, as toilet facilities are not available. In industrial areas, heavy metals, plastics and other persistent organic compounds including insecticides, are the major causes of soil pollution. Hazardous wastes in soil, often accumulate in the bodies of organisms including man, because they are not excreted. Once they enter the food chain, they become more concentrated at each level. 
           One of the example is DDT, a pesticide which becomes more concentrated as it passes along from producer to consumers. The story of DDT is one everybody should know. It was once a widely used pesticide. It is a substance that does not easily break down. It can persist in the environment for as long as fifteen years. It enters birds through the organisms they feed on which in turn get it from the organisms lower in the food chain. When a high concentration builds up in birds their reproductive systems are affected. As a result, they lay fragile eggs that easily break in the nests. Similarly, other pesticides are also major soil pollutants, because of their retention in soil. The pesticides not only kill the targeted pests but also kill many harmless and even beneficial insects. They cause more harm than benefit. Therefore, DDT and many such agrochemicals have been banned in many parts of the world.

Q.  How to minimize soil pollution?                    
A. First of all, in India, the use of open fields and banks of ponds and tanks as open toilets should be stopped, by providing latrines. Care should be taken while dumping wastes in the soil. Substances such as heavy metals, plastics, and other substances that remain unchanged for a very long time should not be added to the soil. Instead, ways should be found for their re-utilization by various recycling processes. Utmost care should be taken so that the minimum necessary pesticides or other agrochemicals are used. In fact. biological control of pests and fixation of nitrogen should be urgently developed by research, so that dependence on the widespread use of toxic chemicals is reduced.

Q.  List five essential components of land management.  
Or  Define land management                        
A.  There are five essential components of land management:
i)  Drawing up of a land capability map indicating soil productivity and the ability to support various human activities in rural and urban areas. This kind of map is prepared with the help of aerial photos and satellite imageries. The map can also give information regarding the properties of rock and soil and the underground potentials of water reserves.
ii)  A detailed study of various aspects of land, such as type of soil, physical features of the earth's crust, water resource input, its distribution, utilization, surface flow, surface storage, for example in ponds and groundwater. A program of land use can be worked out on the basis of such information.
iii)  Changes resulting from land use have to be monitored. This can be done by remote sensing.
iv)  Investigation and estimation of the anticipated intensity of natural hazards likely to
threaten a particular area or region.
v) A comprehensive study of the programme and plan of land management with a view to preserving the land from erosion or soil sickness.                 
          Land should be used according to its suitability and capability. Since food for an increasing population requires more land for cultivation, the encroachment of fertile agricultural lands for non-agricultural purposes like construction of roads and buildings should be reduced to the minimum. Extreme care should be taken in selecting sites for the development of industries, construction of dams and water reservoirs, etc., so that the environment and socio-economic conditions of the people living in that area are not disturbed. In locating sites for the development of urban centers, the need for housing, water supply, disposal of waste and garbage, etc. should be taken into consideration.
             Hill areas, as far as possible, should be put under forest cover because forests serve as a resource for fuel, fodder, and timber, and provide space for animal farming. Besides, forests help in increasing the ground water, since they impede the free surface runoff, thus allowing water to be absorbed by the ground. In this process, soil erosion is minimized and flooding can be avoided. Forests help to maintain a balance in the ecosystem, that is, among animals, plants, air, and water, etc.

Q.  Describe the remote sensing method used for the exploration of land and water resources. Give the importance of resource mapping.  
A.  Remote sensing is a method of collecting information about ground objects like soil, water, vegetation, and minerals, from a remote place, such as an aircraft or a satellite. This technique not only enables us to locate various resources but also helps us to know about their quantity and quality. The simplest device could be a camera carried by an aeroplane to photograph large areas of land systematically. Cameras can also be mounted on satellites and they could take pictures showing details of clouds, water, forests or buildings on the earth. Both these are "optical" methods of remote sensing because visible light is used by the cameras. But one can also send out radio waves from the satellites and observe how they are reflected or absorbed on the surface of the earth. Usually, radio waves of wavelengths as small as a few centimeters called 'microwaves', are used for such studies, because these waves penetrate through clouds and their reflections also go through the clouds to reach the satellite. Similarly, infrared signals can be sent from the satellite and reflections studied to reveal the nature of the reflecting surface
Remote sensing of water resources
Radio waves of the shortest wavelength are called 'gamma rays' which are given off by atoms of several elements. As a result, the ground soil sends out gamma rays which can be picked up by detectors in the aeroplanes or satellites. This emission is affected by the presence of moisture or water in the soil and hence, it can be easily detected whether or not the soil holds water. Moreover, in the pictures taken from space, the wet soil will have an altogether different appearance compared to dry or waterless soil. Due to the presence of moisture, the water-rich soil will show day time (diurnal) variation in temperature on its surface compared to dry soil, and also will also have a cover of vegetation. Analysis of the type, density, and pattern of the vegetation growing on the wet soil helps us in locating the areas of potential ground water. Similarly. the belts of hot springs can be identified with the help of thermal or infra-red detectors.
Search for mineral deposits
Aerial photos and satellite pictures show very clearly if there is a break in the continuity of layers of rock or other unusual features on the surface of the earth. The distinctive linear features are found to be very common where mineral deposits and ground water are accumulated. Radio waves & magnetic measurements also provide information about minerals and oil under the surface.
Survey of the vegetation cover
Forests of deciduous trees shed leaves during the autumn season which can be easily identified with the help of pictures taken from the spacecraft. During the autumn season when the deciduous trees shed leaves and there is no snowfall as yet to conceal the vegetation pictures becomes helpful. Vegetation cover can be studied by measuring and analyzing infra-red reflection, or with the help of photographs. The density of vegetation, shape, and size of the plants and even the size, orientation and health of the leaves can be studied from afar.

Q.  In what way human activities have caused intrusion into the carbon cycle, Nitrogen cycle and water cycle?
A.  Intrusion into the Nitrogen Cycle
Human intervention can disturb the nitrogen cycle. When we grow and harvest crops, there is a loss of nitrogen from the soil, as it is utilized in the building up of plant body. Similarly, harvesting of timber results in a heavy outflow of nitrogen from our forest ecosystem. On the other hand, the heavy addition of commercial fertilizers can cause an excessive build-up of nitrogen in the soil and groundwater. Automobile and industrial exhausts add nitrogen, especially nitrogen dioxide, at an alarming rate to the atmosphere causing acid rain. Nitrogen dioxide reacts with moisture in the atmosphere to form weak nitric acid, which is carried to the soil during rainfall, and ultimately to the water table. This results in nutrient enrichment of rivers, lakes, etc; the presence of excessive nitrogen oxides in the atmosphere; and the excessive availability of nitric acid to the soil.

Intrusion into the Carbon Cycle
In the present century, the carbon cycle has been impaired by non-judicious utilization of fossil fuels, indiscriminate cutting of forests and changes in land use from agriculture to the cement and concrete roads and buildings, which reduces the area under plantation. The burning of fossil fuel by industry and transportation vehicles keeps adding carbon dioxide to the air and due to deforestation, CO2 can’t be removed from the atmosphere. If the amount of carbon dioxide in the air keeps on increasing, it will lead to an increase in temperature on the earth. This is because CO2 traps the heat radiation from the sun and this process is called the greenhouse effect. This will lead to an increase in the temperature of the globe and thus leads to global warming.
    Since 1958. the concentration of carbon dioxide in the atmosphere has risen by almost 6 percent and is expected to increase in the future. If the present trend continues, it is feared that a doubling of atmospheric carbon dioxide could occur sometime towards the middle of the next century, and this would cause an average annual temperature rise of 3 to 8OC. This rise in temperature could have a disastrous impact on all life. It will affect agriculture, resulting in problems in the availability of food and other agriculture-based activities. Melting of polar ice would result in the rise of sea level. This could submerge many coastal areas. It is feared that cities like London, Glasgow, Florida, Tokyo, Osaka, Montreal, Stockholm, Copenhagen, and Calcutta would lose much of their territory to the rising waters.

Intrusion into the Water Cycle
Water management is one of the leading concerns of man today. Due to human actions, the water table has been disturbed. The amount of water that is fit for human consumption has decreased over the years and its quality has deteriorated. To a large extent, this is because of increased population, higher demands of water for personal use, agriculture and industry. Deforestation due to the indiscriminate cutting of trees and the ultimate depletion of the vegetation cover is another major reason. Deforestation, not only reduces the humidity in the atmosphere but also leads to a chain of other undesirable events, for instance, the vegetation that helps to hold the soil together, when reduced considerably, is not able to hold the topsoil. This eventually results in washing away of fertile, topsoil during rainfall or by blowing winds, thus exposing harder infertile rocks. Not much water seeps down the hard soil, and the underground water reservoirs are not properly replenished. The loosely bound soil is carried along by running water on its surface and is ultimately deposited in river beds and dams, thus choking them.
          The other human activities that disrupt the water cycle are: excessive use of agrochemicals which when percolates pollute underground water. Domestic and industrial wastes are often released into the water streams without treatment, adversely affecting life in the water.

Q.  In the present condition, why is it important to manage our resources? Suggest ways to manage our forest and water resources.  
A. Our resources are available in limited quantity and if they are not used judiciously they will get exhausted soon. It is, therefore, necessary for us to make proper planning, to use of our limited resources.
 Management of Forest Resources
It has become necessary to find alternative fuels as well as raw materials to manufacture paper, printing material, sports goods, packing cases, furniture and beams used in Building construction, etc. Another way is to cultivate quick-growing trees in large numbers in selected areas of degraded or wastelands. This will provide us fodder, fuelwood, timber, fruits, and seeds. If deforestation has to be stopped some necessary steps have to be taken:
i) adoption of a scientific method of harvesting forest stocks,
ii) developing a mechanism of monitoring forest growth rate and depletion,
iii) establishing an effective mechanism of fighting forest fires,
iv) strictly enforcing laws to deal with unauthorized cutting down of trees.
Tree plantation
Plantation of fast-growing trees such as poplar, casuarina, etc. should be undertaken on a mass scale. The productivity of tree plantation is found to be greater than that of natural forests. In a well-irrigated tree farm, the productivity may be as high as 45 tonnes per hectare per year.
Social forestry
A farmer can partly meet his needs of wood from the fast-growing trees planted within the limits of his village, along the footpaths, roadsides, alongside railway tracks, side roads or canal, and streams, boundaries of fields and empty spaces. The aim of social forestry is to meet the needs of fuel, fodder, fruits, timber, and other requirements.

Q.  How air pollution is the major problem. How to control air pollution    
A.  Wastes in the form of smoke from industry, power plants, automobiles and homes; and also due to the burning of fossil fuels, spread pollution into our atmosphere. Aircraft also release large amounts of burnt or unburned fuel into the air. The burning of coal, wood, diesel oil, kerosene, petrol, etc. produces the following five
categories of pollutants:
i)   Carbon monoxide
ii) Hydrocarbons
iii) Particulates
iv) Sulphur.dioxide
v) Nitrogen oxides
These five categories of primary pollutants react with one another, producing secondary pollutants that are even more dangerous to animal and plant life.
Carbon monoxide is produced when organic materials such as gasoline, coal, charcoal, and trash are incompletely burnt. Virtually all stoves, furnaces, fires in open places and forests, factories, power plants give off carbon monoxide. The other significant source is from the incomplete burning of tobacco when smoked. This gas combines with hemoglobin, and reduces the oxygen-carrying capacity of the blood, causing blurred vision, headache & in extreme cases unconsciousness & even death.
Harmful impacts are -
Photochemical Smog
Acid rain
Global warming
Depletion of the ozone layer

Controlling Air Pollution 
i) Photochemical smog-eliminating this would require large scale changes in lifestyle and culture. Life has become fast, and quicker modes of transport are preferred. Every year hundreds of thousands of vehicles are added to the existing large number of automobiles. So the net result is an increased production of oxides of nitrogen, and the photochemical smog. The alternative is to develop transport of a very different kind, perhaps electrically operated cars, and two-wheelers rather than those burning petrol, or to make the automobile industry develop devices that could be fitted to the vehicles to minimize the discharge of pollutants.
ii)  Particulates generated largely by industries can be controlled by scrubbers, precipitators, and filters.
iii)  To control sulphur dioxide, which is produced largely by coal furnaces and coal-fired steam generators. several possibilities are available. One is to change from high sulphur to low sulphur fuel, such as natural gas. oil or nuclear fuel.
iv) The amount of smoke emanating from the kitchens can be minimized by the use of smokeless chulhas solar cookers and biogas. These have a dual advantage. One. they are within the easy reach of people and secondly, there is minimum pollution.

FST -1

9th Part


Given above is a figure, based on which the following questions are given. Answer them. 
(i) What ecological phenomenon has been depicted in the figure? Define it.
A.  The figure depicts the food chain. Within an ecosystem, there are many different food chains. Some organisms are involved in several of the food chains at the same time. So a number of food chains become interwoven into a food web. interlocking food chains provide stability to the ecosystem.

(ii) Select and name some organisms and use them to prepare a food chain with four trophic levels.
A.   Plants ----> Goat ------> Wolf -------> Lion
B.   Plants ------> Rat -------> snake -------> Hawk

(iii) State the terms for the trophic levels, naming the components of the constructed food chain. 
A.  Solar energy is converted by plants into food materials which are consumed by the goat, the goat is consumed in the next step by the wolf and in the end wolf by a lion which is the last stage.

(iv)  What happens to the energy flow through the constructed food chain? Who gets the least energy and why?
A.  The energy from the producer to the last level decreases considerably. The loss of energy in the form of heat given out by different organisms. Energy flowing through an ecosystem is thus first captured by the producers. From the producers, the energy passes to various consumers, via food. At the end of the chain, we find that very little energy is left for the last trophic level because some energy is always lost in going from one level to the next. This loss of energy limits the number of trophic levels in the ecosystem, and so they are seldom more than five. This also clearly shows that why the steps in a food chain are limited to four or five. Lion gets the least energy. 

(v) Name the principal source of energy for any ecosystem. Is it a renewable or a non-renewable source, and why? 
A.  The principal source of energy for any ecosystem is sunlight which is renewable energy. Solar energy is converted by plants into food materials and is stored within the body of the plant. All food materials that we or other animals consume are manufactured directly or indirectly by plants. It is renewable as it is not coming from fossil fuels.


Q.  Resource Mapping                          

A.  Using various techniques like remote sensing, satellite imaging, etc. resource Mapping is done to locate different resources like water, minerals, forests. vegetation as well as the types of land. Mapping of resources makes it possible to visualize how land use could be managed to the best advantage. The rural land use map tells us about the health of forests and the state of deforestation, about pastures, and agricultural crops. It also tells us how much land and of what kind is unutilized. The urban land use maps show housing, commercial buildings, sports facilities, essential services such as roads, water supply and disposal of waste, etc. Likewise, the preparation of regional land use maps will focus upon the broader aspects of development such as land used for agriculture, industrialisation and urbanization, for obtaining natural resources (forestry, mining etc.), water resource development (dams, reservoirs and canals), transportation network (rails, road etc.) and also the zones prone to natural hazards like floods, cyclones, earthquakes, landslides and avalanches etc.


Q.  Distinguish between renewable and non-renewable resources giving any two examples of each type.            

A.  Renewable - Some of the resources of the earth are replaced from time to time by natural multiplication as for example, is vegetation. In other words, these resources are inexhaustible and are therefore called renewable resources. Forests, pastures, wild life. and aquatic life is renewable resources. Water is also a renewable resource because it recycles.


Non-renewable - There are some resources, such as minerals, coal, petroleum, gas, etc which once consumed are lost forever. They cannot be regenerated nor expanded. Mineral deposits were formed slowly in millions of years. Once a deposit is used, it cannot be regenerated. For example, petrol gets burnt up and cannot be recovered. These are known as non-renewable resources. Similarly, the formation of soil is a very slow and long term process and it takes thousands of years. It is, therefore, not renewable in the life span of even several generations of people. Hence it is also a non-renewable resource.



Q.  (a) Write a brief account on the causes and effects of deforestation in India. Support your answer with appropriate real-life examples. Name the states in India where maximum deforestation has occurred.    

A. Causes for deforestation
Shifting cultivation, i.e., the process of slashing and clearing of the forest, burning much of the fallen vegetation and cultivating a mixture of crops for two or three years, until the soil loses its productivity is one of the prime reason for deforestation.
The conversion of forests to pastures for cattle grazing. 
Overgrazing - Grazing intensity is high in most of the forest areas of India. This has depleted vast forest areas. In addition to.depletion of vegetation cover, trampling by cattle, hardens the soil, preventing forest regeneration. When there are no plants, the soil becomes loose, and is lost by winds or is washed off by heavy rains.
Commercial exploitation of forests due to the increasing demand for timber is one of the main causes of forest destruction. Wood (for building for making boxes to transport goods, for making paper, and just for burning) is in great demand, and this represents a major threat to our lush green forests.
#  Developmental activities such as irrigation projects, the building of roads, etc. have led to the destruction of forests. This amounts to acquiring good things, like roads, by losing something which is even better.


Effects - Destruction of forests causes soil erosion, silting of lakes & rivers, resulting in devastating floods and loss of thousands of species of plants and animals forever. Trees can grow on hillsides, even when the soil layer is quite thin. When the trees are cut down to clear them for cultivation and the soil is ploughed, there is less protection from the wind and rain. Heavy rainfall washes the soil off the hillsides into the rivers. The hillsides, thus, are left bare and useless, and on the other hand, the rivers become choked up with mud and silt resulting in floods. The disastrous floods in our country have been attributed largely to deforestation.

               The degradation of forests leads to the destruction of habitat for many species of plants and animals. Presently, over one hundred species of wild animals need immediate protection as their population has dwindled to dangerously low levels. Similarly, many plants, too, have suffered from the onslaught of human activities. In a recent list prepared by the Botanical Survey of India, 135 species of Indian plants have been listed, which need immediate protection for their survival. Similarly, over 200 species of animals all over the world have become extinct.
            According to the satellite data, India lost 1.3 million hectares of forest every year between 1972 and 1982. Arunachal Radesh. Manipur and Andaman & Nicobar Islands are the only areas that fulfill-the stipulation of forest cover in hill regions laid down by the National Forest Policy in 1952. The maximum deforestation has occurred in Madhya Radesh, which lost nearly 2 million hectares, Maharashtra lost one million hectares, Orissa, Andhra Pradesh and Jammu & Kashmir lost nearly a million hectares of forest land each during the above said period.


Q.  List the four types of resource maps.   

A.  Four types of resource maps are - 
Soil Maps showing the types of soil their composition and biological productivity.
Mineral Maps showing locations of various kinds of mineral deposits in relation to settings of the earth's crust.
Hydrological Maps show the presence of underground water aquifers, i.e., rock formation containing water in recoverable quantity, in terms of the depth of water table.
Snow Cover Maps demarcate the extent of snowpacks on high mountains.


Observe carefully above picture and answer the following questions based on it :
(a)What does the picture depict? Define it.
A. The picture depicts a pond, which is an ecosystem. It is made up of basically two types of components: living and non-living. The living components include various types of plants, frogs, birds, fish, turtle, insects and numerous kinds of microscopic life forms called microbes. The water, the dissolved gases such as oxygen, and carbon dioxide, the minerals, soil, and stones constitute the non-living components. The various components of the pond interact with each other. The pond is a small world in itself. Here living organisms are born, they live, breath, feed, excrete, move, grow, mate, reproduce, become food for each other and die within the pond itself.


(b)  Name three abiotic and three biotic components are seen in the picture.

A. The living things that affect an organism are called biotic factors like fish, tortoise, frog. Those things that are not alive are called abiotic factors like temperature, oxygen and carbon dioxide dissolved in the water, minerals dissolved.

(c)  Name three animals seen here and use the names to construct a food chain.
A.  Plants ----> insects ------> frogs ------> Fish ------> Man

(d)  Name the principal source of energy which keeps the system alive.
A.  Solar energy.

(e)  State the ecological role of plants seen here.
A. Solar energy enters the ecosystem mainly through green plants, and also through some kinds of bacteria and algae which are called producers. During the photosynthesis process, green plants use the energy of sunlight along with carbon dioxide and water to produce carbohydrates which we may call food. Photosynthesis produces oxygen as a by-product. To carry on photosynthesis and make food, green plants need not only sunlight, water, and carbon dioxide, but also small amounts of some minerals such as calcium, potassium, and magnesium which is available in dissolved form in the water.
Photosynthesis:
Carbon dioxide + water + solar energy + minerals + food + oxygen


(f)  What happens to the dead bodies and wastes of the organisms seen here? 

A.  Green plants are called producers because they produce their own food. Plants live and die, they may be eaten up by animals who also eventually die. There are organisms - the decomposers which act on dead plants and animals and for their existence. The dead bodies of plants & animals are principal source of food for these decomposers. The decomposers, such as bacteria, fungi and worms, convert the dead bodies of the plants and animals back to their elementary forms.

FST -1

8th Part


Q.  Make a clear and well-labeled diagram to explain the energy flow through an ecosystem.                            

Q.  In a food chain explain why the number of trophic levels is seldom more than four and five. 
A.     The principal source of energy for any ecosystem is sunlight. Solar energy is converted by plants into food materials and is stored within the body of the plant. All food materials that we or other animals consume are manufactured directly or indirectly by plants. Thus, the energy that we obtain from plants either by burning wood or by eating them, represents the solar energy trapped by the plants. We are dependent on the stored resources of solar energy. When we eat meat, we obtain energy that had been stored by plants several years before and then taken up by an animal like a goat through grazing. When we cut firewood for fuel, we obtain energy accumulated & stored by trees for perhaps a century or more. When we bum coal or petroleum, we obtain solar energy stored by plant life, millions of years ago. Now let us trace the energy flow through an ecosystem.
The energy from the producer to the last level decreases considerably. The energy passed on to the next trophic level is represented by letter E of three different sizes, each by its size indicates the comparative amount of energy. The arrows in the upper half of the diagram indicate the loss of energy in the form of heat given out by different organisms. The arrows in the lower half show the energy loss via the wastes secreted and energy trapped in dead bodies of the organisms. Decomposers use these wastes and dead bodies as sources of food and derive energy from them. They also give out some unused heat energy.
          Energy flowing through an ecosystem is thus first captured by the producers. From the producers, the energy passes to various consumers, via food. At the end of the chain, we find that very little energy is left for the last trophic level because some energy is always lost in going from one level to the next. This loss of energy limits the number of trophic levels in the ecosystem, and so they are seldom more than five. This also clearly shows why the steps in a food chain are limited to four or five.


Q.  Define the ozone layer. How did the ozone layer gets depleted?  

A.        The presence of a thin layer of ozone is important for life on the earth. There is an ozone layer about 25 kilometers above the earth's surface. Ozone is a form of oxygen. Each molecule of ozone contains three atoms of oxygen (0,) while there are only two atoms in the ordinary oxygen (0,) molecule. The ozone layer creates a protective shield around the Earth as it absorbs a great deal of ultraviolet radiation coming from the sun. It thus saves us from skin bums, skin cancer, and other harmful effects. An increased level of ultraviolet radiation would cause more skin cancer, affect crops, interfere with the oxygen cycle and even distort weather patterns.
                   There are many reasons for the depletion of ozone. The foremost is the widespread usage of chlorofluorocarbons. These are gases that readily liquify when compressed. This makes them useful in refrigerants, ac, propellants in aerosol cans, and in plastic foams. Chlorofluorocarbons are very stable and accumulate in the atmosphere, where they react with ozone. Nitrogen oxides also play a significant role in ozone destruction. Jet planes flying in the upper atmosphere release fumes containing Nitrogen oxide which destroys the Ozone.


Q.  Write the physical features of oceans and coasts and the ecological crises in the oceans and the coastal areas.      

A.                  Physical Features of the Oceans
               Oceans are the oldest and the largest ecosystems of the earth. They cover more than 70 percent of the earth's surface. The depth of oceans varies, from shallow near the coasts to deep in the middle. There are trenches, valleys, hills under the ocean waters. 
               Ocean waters are never still. Wind exerts a frictional force on the surface of the water and generates waves that keep the surface water in motion. Tides are another type of movement of the oceanic water, noticeable in coastal regions. The water level of the sea rises and falls twice a day. The gravitational pull of the sun and the moon is the principal cause of the formation of tides. Coastal waters rise to a high point called the high tide when the sun and the moon are on the same side of the earth, and the tide is low when the sun and the moon happen to be on the opposite sides. Ocean currents are yet another form of water movement. Currents are generated in several ways: by changes in the density of seawater, due to temperature differences, by the effect of earth's rotation and also prevailing winds. These currents transport seawater over long distances, more or less like rivers on the surface of the earth. 
            Ocean water is salty. It has about 35 parts of salt (by weight) per 1000 parts of water. Ordinary salt or sodium chloride is the major salt component of the oceanic water. Salts of magnesium, calcium, and potassium are also present. This substantial amount of salt in seawater is the result of the accumulation of small bits of salt that are carried by rivers from the lands they drain.
                Oceanic waters have a minimum temperature well below zero Celsius, near the poles, and a maximum of about 28 Celsius in the tropics. The atmosphere exerts a pressure of about 1 kilogram per square cm (= 1 Atmosphere Pressure) at the surface of the sea or land. This pressure increases due to the weight of water by 1 Atmosphere, for every 10 meters of the depth of water.
                  Ecological Crises in Oceans and Coasts
Coastal and marine areas all over the world including those in India are under stress because two-thirds of the world's population lives near the coasts, and 60% of the marine food is harvested from the zone near the coasts. Most of the sewage, garbage, and industrial wastes find their way into the sea. So the industry produces massive amounts of "waste" which is allowed to reach the sea. As a result, huge quantities of dead fish were found floating in the Arabian Sea on the west coast due to poisonous outflows from a fertilizer factory.
          The rivers, which join the seas, bring sand from the hills and plains, and thus a lot of silt gathers near the coasts. Rivers also bring to the seawater, runoff from the fields, which, today. means a certain amount of fertilizers and pesticides. A new factor has recently come to light and that is chemicals from nuclear power plants and the nuclear industry. This waste has radioactive chemicals that can demolish and destroy living organisms in ocean waters. A number of times it has been reported that ships, particularly tankers, transporting oil leaves a trail of oil along their routes. A thin layer of oil thus covers wide areas of the surface seawater, depriving living organisms of oxygen.


Q.  Describe the various ways of management of soil.        

A.     Soil is a precious resource that takes millions of years to form, and hence proper management of soil is very necessary. The management of the soil is two-fold, i.e. (a) to minimize or check soil erosion and (b) restore the productivity of the soil.
Control of soil erosion
The most significant measures of erosion control include - 
(i) growth of grasses, shrubs, and trees on soils and 
(ii) construction of a drainage system that can prevent free, uncontrolled flow of water. 
               Uncontrolled water flow causes the formation of narrow channels or gullies and it further leads to the development of deep narrow valleys leading to ravine land for ex. the famous Chambal ravines. This can be controlled by constructing a series of check dams that prevent the flow of running water and widening of gullies. Construction of a broad wall of stone along the coasts of Maharashtra, Kerala, Andhra Pradesh, and Orissa has proved to be very effective in controlling erosion by sea waves and currents.  
                Movement of sand by drifting winds in the deserts and sandy coasts can be prevented by putting barriers of trees and shrubs across the path of the wind. In the mountain and hilly areas, planting of self-propagating trees and shrubs, not only strengthens the slope of the hills but also provides fuelwood and fodder to the general population. Alternate cultivation of beds of crops with strips of erosion-resistant vegetation like grasses, shrubs. trees, maize, sugarcane, cotton, and tobacco, etc. bring about stability of the terraced fields on mountainous and hilly areas. The most effective step in controlling erosion and mass movement, such as landslides in the hills, is the construction of a network of the drainage ditches which are filled with fragments of stones or bricks so that water flows out through them. The hill slopes are stabilized by constructing walls around them which allows the free passage of water. On the vulnerable slopes, a cover of vegetation is provided and here, seeds are covered with coir netting pegged firmly to the ground. Netting checks erosion holds the soil material together and adds nutrients. The quick growth of grass stabilizes the soil.


Q.  How does photochemical smog form?           

A.  Photochemical smog, a secondary Pollutant, results when the two pollutants, nitrogen oxide and hydrocarbons found in automobile exhausts, react with one another in the presence of sunlight to produce nitrogen dioxide (N02), ozone (03) and a compound called PAN (Peroxylacetyl nitrate), which then appear as a yellowish-brown haze. Breathing ozone affects the respiratory and nervous system. It causes respiratory distress, affects eye membranes and stimulates tears. It also causes a headache. Ozone also damages rubber articles, textiles and discolors paintings. It has been recently found that smog is harmful to timber. PAN is
especially damaging to plants. Plants exposed to PAN exhibit leaf mottling.

Q.  (i) Explain six ways by which water bodies of a country get polluted.
(ii) How does aquatic fauna get killed due to 
(a)heavy metal pollution and (b) eutrophication?             
A. 1.  Power plants, fertilizer factories, steel mills, paper mills, refineries, sugar factories, and automobile factories are examples of industries that mostly dump their wastes in rivers or into the sea thus polluting water resources.
2. Community wastes (sewage and garbage) from urban and rural settlements account for four times as much dirty water as industrial wastes. Most of these wastes are discharged untreated into the water sources.
3.  Water which is used to irrigate agricultural fields where fertilizers, pesticides, insecticides, and other agrochemicals are used, contributes much to the pollution of water sources. This water, on absorption also pollutes the underground sources.
4. Nuclear and thermal power stations use large quantities of water for cooling purposes. They discharge the resultant hot water often containing chemicals, into water streams. This results in an increase in temperature of the water of the stream, which is injurious for fish, and other aquatic organisms.
5. Pollution of river water by ferries which leave a certain amount of oil on river surfaces and similar pollution by ships on the high seas interferes with the supply of oxygen needed for plants, and animals such as fish, etc. in water. Offshore exploration for petroleum and accidental oil spills cause similar problems for under-water life.
6. Acid water from mines, and also from rain pollutes water in rivers and in the sea.
7. Suspended particles in the air, such as the pesticides sprayed through an aircraft are brought down into the water bodies by rain and thus cause pollution of water.
        Heavy metals such as lead and mercury coming out of industrial wastes pollute the under ground water. Excessive use of fertilisers, insecticides, pesticides in the fields, which gradually seep down to the ground water also pollute it. Such heavy metals like Mercury is not easily excreted. Once it enters the food chain its concentration goes on increasing at each level. For example, from plants+ large fish -+human beings. Large no. Of fishes die due to it and also becomes unsafe for consumption.