Get summay, questions, answers, solutions, notes, extras, PDF, competency-based questions of chapter- 6/unit I, Social Issues and Environment: AHSEC Class 11 Environmental Education, which is part of the present syllabus. These solutions, however, should only be treated as references and can be modified/changed.
Summary
Growing populations and industries have placed great strain on our planet’s natural resources, like land and water. This has led to a decline in environmental quality. To address this, the idea of sustainable development was introduced. Sustainable development means meeting our current needs without preventing future generations from meeting their own. It is about finding a balance between economic growth and protecting the environment. This concept gained attention after a report called “Our Common Future” was published in 1987 and was further discussed at the 1992 Earth Summit.
Development requires a lot of energy. Energy is the power to do work. There are two main types of energy sources. Renewable sources are those that do not run out, such as solar, wind, and hydropower. Non-renewable sources are limited and will eventually be used up, like coal, petroleum, and natural gas. Using too much energy, especially from non-renewable sources, can harm the environment. Energy conservation is the effort to reduce energy use. This can be done by using energy more efficiently and switching to renewable sources. Conserving energy helps protect the planet and can reduce global warming.
Water is another precious resource. Rainwater harvesting is a method of collecting and storing rainwater from rooftops and open spaces. This stored water can be used later, which reduces the demand on groundwater. It is a simple technique that helps manage water supplies, especially in areas with irregular rainfall. A clean environment is also necessary for good health. The World Health Organization states that health is a state of complete physical, mental, and social well-being. Polluted water can cause many diseases. Air pollution from industries and vehicles also poses serious health risks.
Our planet is kept warm by a natural process called the greenhouse effect. Gases in the atmosphere, like carbon dioxide, trap some of the sun’s heat, acting like a blanket to keep Earth at a comfortable temperature for life. However, human activities have released too many of these gases, making the blanket thicker. This traps too much heat and causes the Earth’s temperature to rise, a phenomenon known as global warming. This warming leads to climate change, which involves long-term shifts in weather patterns. Another environmental issue is the depletion of the ozone layer, a protective shield in the atmosphere that blocks harmful ultraviolet rays from the sun. Certain man-made chemicals called CFCs have damaged this layer. International agreements like the Montreal Protocol were created to stop the use of these harmful substances. Finally, pollution from burning fossil fuels can lead to acid rain, which occurs when pollutants mix with water in the atmosphere and fall to the ground, harming forests and lakes.
Textual/Exercise
1. What do you mean by sustainable development ?
Answer: According to Brundtland, sustainable development is development that meets the need of the present without compromising the ability of the future generations to meet their own needs.
2. What are renewable and non-renewable energy resources ? Give examples.
Answer: Renewable energy resources are generated continuously in nature and are in-exhaustible. For example – solar energy, wind energy, hydropower energy, geothermal energy, ocean thermal energy, tidal energy, wood, biomass energy, bio-fuels, hydrogen etc. They can be used again and again and are the non-conventional or alternative sources of energy.
Non-renewable energy resources are sources that have accumulated in nature, have been in use for a long time, and are exhaustible. Once these sources are finished, they cannot be replenished quickly. For example, fossil fuels (coal, petroleum, natural gas), and nuclear fuels like uranium and thorium. These are used conventionally to meet the energy demands of human society.
3. What is energy conservation ? Mention some measures for energy conservations.
Answer: Energy conservation refers to efforts made to reduce energy consumption. It can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources.
The following measures for energy conservation can be adopted as initial steps:
a) Shifting from the use of fossil fuels and non renewable energy resources such as petroleum, coal, natural gas, uranium etc to renewable energy resources such as solar energy, wind energy, biogas etc.
b) More technological innovation contributing efficient energy saving.
c) Unnecessary use of electricity should be prohibited. Switch off the street lights early in the morning.
d) Domestic consumers can curtail energy consumption on many household goods.
e) Industries should develop a mechanism for judicious use of raw materials for their energy needs.
4. What is rainwater harvesting ? What are the objectives of rainwater harvesting ?
Answer: Rainwater harvesting is a technique of collection of rainwater from paved or G.I. corrugated roofs and paved courtyards of houses. It is also involved in increasing the recharge of groundwater by capturing and storing rainwater. This is done by constructing special water harvesting structures like dug wells, percolation pits, lagoons, check dams etc.
Rainwater harvesting has the following objectives:
- To reduce run off loss
- To meet increasing demands of water
- To reduce pressure on ground water resource
- To raise ground water table by the process of recharging
5. What are the advantages of rainwater harvesting ?
Answer: The advantages of rainwater harvesting are:
- It provides a source of water at the point where it is needed.
- It involves little cost and every household can easily accommodate the simple mechanism required for recycling rainwater.
- Rainwater is free from the contamination of fluoride, arsenic, iron etc.
- Recycling of rainwater for domestic and other uses can significantly reduce the pressure on ground water as ground water depletion has become a serious problem in many cities of the world.
- It provides an essential reserve in times of emergency or breakdown of public water supply systems.
- The technologies are simple and common people can easily be trained to build one storage tank of rainwater with a minimum cost.
6. How health may be affected by the environment ?
Answer: Human health is affected by the environment. Many factors like nutritional, chemical, physical, biological, psychological, and poor living conditions are correlated. More than 80% of diseases in India are water-related, including typhoid, cholera, hepatitis, polio, gastro-enteritis, amoebiasis, and giardiasis. The most common health risk from drinking water is microbial contamination. Many toxic chemicals, pesticides, and heavy metals like mercury, cadmium, and lead are released into water bodies and soil, which can enter the human body through the food chain, causing adverse impacts on health. Industries and transportation systems release gases like sulphur dioxide, carbon monoxide, and nitrous oxide, which can cause different health effects. Solid waste can degrade the air, water, and soil, posing risks to health. Improper housing with poor hygienic conditions can also cause serious health effects.
7. ‘Population explosion is the root cause of environmental degradation’- Explain the statement.
Answer: The bourgeoning population, rapid urbanization, and accelerated rates of industrialization in recent times have brought about tremendous pressure on land, water, and other natural resources. This leads to the deterioration of environmental quality, loss of life forms, and depletion of vast natural resources. The deterioration of environmental quality is inextricably linked with economic growth and development.
8. What are the major greenhouse gases ? What is greenhouse effect ?
Answer: The major greenhouse gases (GHGs) are carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), water vapour, and ozone.
The greenhouse effect is a process where energy from the sun is absorbed by the earth’s surface, which then releases it as infrared radiation. All of this rising heat is not lost to space but is partly absorbed by greenhouse gases present in the atmosphere. These gases re-emit some of the heat back to the earth’s surface. This effect is called the greenhouse effect because it is similar to the warming effect observed in a horticultural greenhouse made of glass.
9. What do you mean by global warming ? Mention a few consequences of global warming.
Answer: The rise in temperature due to the blanketing effect of an increased level of greenhouse gases is termed global warming.
A consequence of global warming is that the earth’s average temperature has increased by 0.3 – 0.6°C since the beginning of the last century. This leads to climate change, which includes unexpected changes such as rising temperatures, changes in rainfall patterns, increased droughts, and extreme colds.
10. What is acid rain ?
Answer: Oxides of sulphur and nitrogen originating from industrial operations and fossil fuel burning are the major sources of acid-forming gases in the atmosphere. When sulphur dioxide and nitrogen oxides are transported by prevailing winds, they come in contact with water vapour and form sulphuric acid and nitric acid respectively, droplets of sulphuric acid, and small particulates of sulphates and nitrates. These chemical substances come down to the earth’s surface in two forms – wet (as acid rain, snow, fog, and cloud vapour etc.) and dry (as acidic particles). The resulting mixture is called acidic deposition or commonly called acid rain.
Extra/additional questions and answers
1. What is Agenda 21?
Answer: Agenda 21 is a detailed action plan for achieving sustainable development in the 21st century. It was one of the documents that came from the ‘Earth Summit’.
47. Distinguish between Global warming and Climate change.
Answer: Global warming: This is the rise in temperature due to the blanketing effect of an increased level of greenhouse gases in the atmosphere.
Climate change: This is a broader term that refers to statistically significant variations in the mean state of climate or in its variability over an extended period. It is used to express unexpected changes in climate, which include not only rising temperature but also changes in rainfall patterns, increased droughts, and extreme colds.
Extra/additional Fill in the Blanks
1. The concept of sustainable development gained much importance since the publication of the Brundtland Report, Our Common Future, in ______
Answer: 1987
29. Oxides of sulphur and ______ are the major sources of acid-forming gases in the atmosphere.
Answer: nitrogen
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