Science : Chapter 22 : Environmental Management
I. Fill in the blanks
1. Deforestation leads to __________in rainfall.
Ans ; Decrease
2. Removal of soil particles from the land is called __________.
Ans ; Soil erosion
3. Chipko movement is initiated against __________.
Ans ; Cutting trees / Deforestation
4. __________is a biosphere reserve in Tamilnadu.
5. Tidal energy is ___________ type of energy.
Ans.: Non-conventional / Renewable
6. Coal, petroleum and natural gas are called __________fuels.
Ans ; Fossil
7. __________ is the most commonly used fuel for the production of electricity.
Ans ; Coal
II. State whether True or False. Correct the statements which are false
1. Biogas is a fossil fuel. ( False )
- Biogas is a Bio-fuel.
2. Planting trees increases the groundwater level. ( True )
3. Habitat destruction cause loss of wild life. Ans.: True.
4. Nuclear energy is a renewable energy. ( False )
- Nuclear energy is a non-renewable energy.
5. Overgrazing prevents soil erosion. ( False )
- Overgrazing increases soil erosion.
6. Poaching of wild animals is a legal act. ( False )
- Poaching of wild animals is a illegal act.
7. National park is a protected park. ( True )
8. Wild life protection act was established in 1972. ( True )
III. Match the following
- Soil erosion – energy saving
- Bio gas – acid rain
- Natural gas – removal of vegetation
- Green house gas – renewable energy
- CFL bulbs – CO2
- Wind – non-renewable energy
- Solid waste – lead and heavy metals
Ans ; 1 – C, 2 – D, 3 – F, 4 – E, 5 – A, 6 – B, 7 – G
IV. Choose the correct answer
1. Which of the following is / are a fossil fuel?
|i. Tar||ii. Coal||iii. Petroleum|
- i only
- i and ii
- ii and iii
- i, ii and iii
Ans ; i, ii and iii
2. What are the steps will you adopt for better waste management?
- reduce the amount of waste formed
- reuse the waste
- recycle the waste
- all of the above
Ans ; All of the above
3. The gas released from vehicles exhaust are
|i. Carbon monoxide||ii. Sulphur dioxide||iii. Oxides of nitrogen|
- i and ii
- i and iii
- ii and iii
- i, ii and iii
Ans ; i, ii and iii
4. Soil erosion can be prevented by
- over grazing
- removal of vegetation
Ans ; Afforestation
5. A renewable source of energy is
- nuclear fuel
Ans ; d) trees
6. Soil erosion is more where there is
- no rain fall
- low rainfall
- rain fall is high
- none of these
Ans ; rain fall is high
7. An inexhaustible resources is
- wind power
- soil fertility
- wild life
- all of the above
Ans ; wind power
8. Common energy source in village is
- wood and animal dung
Ans ; wood and animal dung
9. Green house effect refers to
- cooling of earth
- trapping of UV rays
- cultivation of plants
- warming of earth
Ans ; warming of earth
10. A cheap, conventional, commercial and inexhaustible source of energy is
- solar energy
- wind energy
- thermal energy
Ans ; hydropower
11. Global warming will cause
- raise in level of oceans
- melting of glaciers
- sinking of islands
- all of these
Ans ; all of these
12. Which of the following statement is wrong with respect to wind energy
- wind energy is a renewable energy
- the blades of wind mill are operated with the help of electric motor
- production of wind energy is pollution free
- usage of wind energy can reduce the consumption of fossil fuels.
Ans ; the blades of wind mill are operated with the help of electric motor
V. Answer in a sentence
1. What will happen if trees are cut down?
Effect of cutting trees
- Ecological problems like floods and drought
- Soil erosion
- Loss of wild life
- Extinction of species
- Imbalance of biogeochemical cycles
- Alteration of climatic conditions and
2. What would happen if the habitat of wild animals is disturbed?
The habitat provides food, shelter and protection to the animals. If the habitat is disturbed then the animals become unprotected and may decline in numbers and become endangered.
3. What are the agents of soil erosion?
Agents of soil erosion are
- High velocity of wind,
- Air currents,
- Flowing water,
- Human activities (deforestation, farming and mining) and
- Overgrazing by cattle.
4. Why fossil fuels are to be conserved?
Conservation of fuels is essential due to following reasons:
- They are limited. Once they are exhausted there will be none.
- There are no ideal alternative for fossil fuels.
- We have to use in a control way to control global warming.
5. Solar energy is a renewable energy. How?
Solar energy is the energy obtained from the sun. It is a renewable free source of energy that is sustainable and totally inexhaustible, unlike fossil fuels which are finite.
6. How are e-wastes generated?
E-wastes are generally called as electronic wastes. They are generated from the spoiled, outdated, nonrepairable electrical and electronic devices.
VI. Short answer questions.
1. What is the importance of rainwater harvesting?
Rainwater harvesting helps to
- Overcome the rapid depletion of ground water levels.
- To Meet the increase demand of water.
- Reduces flood and soil erosion
- Water stored in ground is not contaminated by human and animal wastes and hence can be used for drinking purpose.
2. What are the advantages of using biogas?
Advantages of biogas
- It burns without smoke and therefore causes less pollution.
- An excellent way to get rid of organic wastes like bio-waste and sewage material.
- Left over slurry is a good manure rich in nitrogen and phosphorus
- It is safe and convenient to use
- It can reduce the amount of greenhouse gases emitted.
3. What are the environmental effect caused by sewage?
Careless disposal of sewage water leads to creation of a chain of problems like spreading of diseases, eutrophication, increase in Biological Oxygen Demand (BOD), etc.
- Detergents released in water contain phosphates and they allow the growth of algae and water hyacinths.
- Pathogens present in sewage water are responsible for spreading different kinds diseases. Stagnant water fosters the growth of mosquitoes, which in turn causes diseases like malaria.
- Toxins released in rivers through sewage water are consumed by fish and other aquatic organisms; thus, the possibility of toxins entering the food chain increases manifold.
- The sewage water dumped in oceans can affect the coral reefs to a great extent. The toxins present in polluted water inhibit the growth of corals.
- Water bodies in their natural form contain small amounts of chemical compounds like bicarbonates, nitrates, chlorides, sulphates, etc. So water becomes unsuitable for drinking and irrigation.
4. What are the consequences of deforestation?
Consequences of Deforestation – Deforestation gives rise to ecological problems like floods, drought, soil erosion, loss of wild life, extinction of species, imbalance of biogeochemical cycles, alteration of climatic conditions and desertification.
VII. Long answer questions
1. How does rainwater harvesting structures recharge ground water?
Rainwater harvesting is a technique of collecting and storing rainwater for future use. It is a traditional method of storing rain water in underground tanks, ponds, lakes, check dams and used in future. The main purpose of rainwater harvesting is to make the rainwater percolate under the ground so as to recharge ‘groundwater level’.
Methods of rainwater harvesting :
A) Roof top rainwater harvesting:
Roof-tops are excellent rain catchers. The rain water that falls on the roof of the houses, apartments, commercial buildings etc. is collected and stored in the surface tank and can be used for domestic purpose.
B) Recharge pit :
In this method, the rainwater is first collected from the roof tops or open spaces and is directed into the percolation pits through pipes for filtration. After filtration the rainwater enters the recharge pits or ground wells.
2. How will you prevent soil erosion?
- Retain vegetation cover, so that soil is not exposed.
- Cattle grazing should be controlled.
- Crop rotation and soil management improve soil organic matter.
- Runoff water should be stored in the catchment.
- Reforestation, terracing and contour ploughing.
- Wind speed can be controlled by planting trees in form of a shelter belt.
3. What are the sources of solid wastes? How are solid wastes managed?
Sources of solid waste :
- Municipal wastes
- Hospital wastes
- Industrial wastes
Solid-waste management It involves the collection, treatment and proper disposing of solid material that is discarded from the household and industrial activities.
It is the separation of different type of waste materials like biodegradable and non biodegradable wastes.
b) Sanitary landfill :
Solid wastes are dumped into low lying areas. The layers are compacted by trucks to allow settlement. The waste materials get stabilised in about 2-12 months. The organic matter undergoes decomposition.
c) Incineration :
It is the burning of non-biodegradable solid wastes (medical wastes) in properly constructed furnace at high temperature.
iv) Composting :
Biodegradable matter of solid wastes is digested by microbial action or earthworms and converted into humus.
v) Recycling of wastes :
- Papers from old books, magazines and newspapers are recycled to produce papers in paper mills.
- Agricultural wastes like coconut shells, jute cotton stalk, bagasse of sugarcane can be used to make paper and hard board. Paddy husk can be used as livestock fodder.
- Cow dung and other organic wastes can be used in gobar gas plant to provide biogas and manure
4. Enumerate the importance of forest.
Importance of forest.
- Forests are an important component of our environment.
- Forests consist of economically and medicinally valuable microorganisms, flowering plants, shrubs, climbers and dense trees.
- Forests provide a vast habitat for wild animals.
- Forests also contribute to the economic development of our country.
- Forests are important source for a wide range of renewable natural resource.
- They provide wood, food, fodder, fibre and medicine.
- Forests act as carbon sink, regulate climatic conditions, increase rainfall, reduce global warming, prevent natural hazards like flood and landslides, protect wildlife and also act as catchments for water conservation.
- They also play a vital role in maintaining the ecological balance.
5. What are the consequences of soil erosion?
Removal of upper layer of soil by wind and water is called soil erosion. Soil erosion causes a significant loss of humus, nutrients and decrease the fertility of soil.
i) Fertility loss and land degradation:
The direct and primary effect of soil erosion is soil loss and nutrient leaching resulting in reduction of land roductivity.
ii) Air Pollution :
Wind erosion picks up dust particles of the soil and throws them into the air, causing air pollution.
iii) Destruction of Infrastructure :
Soil erosion can affect infrastructural projects such as dams and drainages. The accumulation of soil sediments in dams and drainages can reduce their operational lifetime and efficiency.
iv) Desertification :
Soil erosion is a major driver of desertification. It gradually transforms a habitable land into deserts.
v) Water Pollution :
Soils eroded from agricultural lands carry pesticides, heavy metals, and fertilizers which are washed into streams and major water ways. This leads to water pollution and damage to marine and freshwater habitats.
vi) Clogging of Waterways :
Accumulated sediments can also cause clogging of water ways and raises the water level leading to flooding.
6. Why is the management of forest and wildlife resource considered as a challenging task?
- People living in and around forests are dependent on forest ie plants and animals products for various aspects of their life such as livelihood.
- The forest department of the government who judicially allowed for owning the land and controlling the resources from forests.
- The industrialists who use forest products such as timber, leaves, latex and raw materials for their industries.
- Global warming and climate change results in water scarcity and changes in rainfall pattern in forest area.
- Lack of proper law enforcement and lack of sufficient number of guards lead to indiscriminate illegal poaching affects wildlife populations and the environment.
VIII. Assertion and Reasoning
Direction : In each of the following question a statement of assertion(A) is given and a corresponding statement of reason (R). Of the four statements given below mark the correct answer.
- Both assertion and reason are true and reason is correct explanation of assertion.
- Both assertion and reason are true but reason is not the correct explanation of assertion.
- Assertion is true but reason is false.
- Both assertion and reason are false.
1. Assertion: Rainwater harvesting is to collect and store rain water.
Reason: Rainwater can be directed to recharge the underground water source.
- Ans : a) Both assertion and reason are true and reason is correct explanation of assertion
2. Assertion: Energy efficient bulbs like CFL must be used to save electric energy.
Reason: CFL bulbs are costlier than ordinary bulbs, hence using ordinary bulbs can save our money.
- Ans : c) Assertion is true but reason is false
IX. Higher Order Thinking Skills (HOTS)
1. Although coal and petroleum are produced by degradation of biomass, yet we need to conserve them. Why?
The formation of coal and petroleum is a very slow process and takes very long period of time for renewal. The coal and petroleum reserves can get exhausted if we continue using them at a rapid rate. So it is necessary to conserve or save coal and petroleum resources for the future use, which can be done by reducing their consumption.
2. What are the objectives for replacing non-conventional energy resources from conventional energy resources?
The objective in using non-conventional (Renewable) resources is to reduce the pessimistic environmental effects associated with conventional (Non-renewable) resources such as coal, petroleum and natural gas. Reusable or non-conventional energy is greener and keeps our planet clean. We need to make sure our future generation need not have to walk around with an oxygen mask on their face.
3. Why is the Government imposing ban on the use of polythene bags and plastics? Suggest alternatives. How is this ban likely to improve the environment?
Government is imposing ban on polythene bags and plastics, because they are non-biodegradable substances and harmful to the environment .
Alternatives to Polythene bags and plastics :
Instead of polythene bag, “Paper Bags” and “cloth bags ” and instead of non-biodegradable plastics, bio-plastics can be used as they are biodegradable and will get decomposed and they will not pollute the environment.
This ban will improve the environment in the following ways :-
- It will help to prevent land and water pollution .
- It will lead to less productions of polythenes , which help in reduction of harmful gases from factories.
X. Value based questions
1. Why is it not possible to use solar cells to meet our energy needs? State three reason to support to your answer.
Solar cells are not used in our daily routine because :
- Solar cells work on the basis of solar energy which is not provided at night. Moreover in the winter season sunlight is minimal.
- They take lot of time in completing any work depending on the intensity of light. For Eg : solar cookers take much time in cooking food in low intensity of light.
- The installing cost of solar cell panel is high as the silicon wafer is very expensive also same for the silver which is used in connecting solar cells.
- Only DC electricity is produced by SPV (Solar Photovoltaic system).To operate any AC device, this dc has to be converted in as by using inverters.
- The efficiency of energy conversion is low as compared to other means of generating electricity.
2. How would you dispose the following wastes?
a. Domestic wastes like vegetable peels
b. Industrial wastes like metallic cans
Can the disposal protect the environment? How?
a) Disposal of vegetable peels and metallic cans
- Peels and scrapings from fruit and vegetables can be composted along with other degradable matter.
- Industrial waste like metallic cans can be recycled as they are non – biodegradable.
b) Disposal can protect environment :
- Biodegradable matter of solid wastes such as Peels and scrapings from fruit are digested by microbial action or earthworms and converted into humus.
- Recycling of industrial waste like metallic cans helps to reduce air pollution, water pollution, greenhouse gas emissions and often a conservation of global resources.
3. List any three activities based on 3R approach to conserve natural resources.
First ‘R’ – Reuse :
Bring cloth bags to the store with you instead of asking shopkeeper for new paper or polythene bags. You can use cloth bags again and again. You can save some trees and can prevent pollution caused by polythene bags.
Second ‘R’ – Reduce :
When we reduce the use of electric power, we reduce the amount of toxic fumes released by power plants, conserve the earth’s natural resources and protect ecosystems from destruction.
Third ‘R’ – Recycle :
Many of the things we use every day, like paper bags, soda cans, and milk cartons, are made out of materials that can be recycled. Recycled items are put through a process that makes it possible to create new products out of the materials from the old ones.