Get notes, summary, questions and answers, MCQs, extras, and PDFs of Chapter 5 “Human Activities and Degrading Environment” which is part of NBSE Class 11 Environment Education. However, the notes should only be treated as references and changes should be made according to the needs of the students.
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Summary
The chapter discusses the impact of human activities on the environment, focusing on how these activities have led to the degradation of natural resources. It begins by explaining how early humans lived in harmony with nature, but as populations grew and technology advanced, humans started to significantly alter the environment. The Industrial Revolution marked a major turning point, leading to widespread exploitation of fossil fuels and natural resources.
The chapter highlights the depletion of essential natural resources like soil, water, and air. Soil erosion, caused by deforestation and poor agricultural practices, has led to the degradation of a significant portion of the world’s cropland. The increasing demand for water, driven by agriculture and industry, is depleting underground water sources, leading to problems such as saltwater intrusion in coastal areas and subsidence in inland regions. Air quality has seen some improvements in industrialized nations, but issues like acid rain persist due to emissions of sulfur dioxide and nitrogen oxides.
The chapter also addresses the effects of urbanization, which has led to various environmental challenges. These include vehicular emissions that contribute to air pollution, land use changes that encroach on natural environments, and the stress on civic amenities like water supply, electricity, and waste disposal. Urban areas face additional problems such as inadequate housing, particularly in slums, and health issues related to pollution and poor sanitation.
In rural areas, the use of synthetic pesticides and inorganic fertilizers has led to soil and water pollution, as well as health risks for both humans and animals. Desertification, caused by overgrazing and overcultivation, is another significant problem in rural regions.
Textbook solutions
Multiple-Choice Questions
1. In which continent is soil erosion least?
A. Australia
B. Europe
C. Antarctica
D. North America
Answer: C. Antarctica
2. Which of the following is not responsible for ozone layer depletion?
A. Ultraviolet rays
B. Aerosol spray
C. Refrigeration
D. Cleaning solvents
Answer: A. Ultraviolet rays
3. Which of the following is not an effect of acid rain?
A. Corrosion of metal
B. Volcanic eruptions
C. Weathering of monuments
D. Acidification of lakes and soils
Answer: B. Volcanic eruptions
4. Why do people migrate from one place to another?
A. To get a better job
B. To improve their access to social amenities
C. For better education
D. All of these
Answer: D. All of these
5. Methaemoglobinemia occurs due to the presence of which of the following in drinking water?
A. Chlorates
B. Sulphates
C. Nitrates
D. Oxalates
Answer: C. Nitrates
Short Answer Questions
1. How have human activities caused soil erosion?
Answer: Human activities have caused soil erosion by degrading one-fifth to one-third of the cropland of the world, posing a significant threat to food supply. In the developing countries, the increasing need for food and firewood has resulted in deforestation and cultivation of steep slopes, causing severe erosion. Adding to the problem is the loss of prime cropland to industry, dams, urban sprawl, and highways. The amount of topsoil lost each year is at least 7.6 million tonnes, which is enough, in principle, to grow 9 million tonnes of wheat. Soil erosion and the loss of cropland and forests also reduce the moisture-holding capacity of soils and add sediments to streams, lakes, and reservoirs.
2. What has caused contamination of water?
Answer: Contamination of water has been caused by a steady decline in the availability and quality of water. Human beings already use 55% of available freshwater runoff. This level of consumption will be an increasing problem as the population rises. About 75% of the world’s rural population and 20% of its urban population have no ready access to uncontaminated water. In many regions, water supplies are contaminated with toxic chemicals and nitrates.
3. What constitutes farm waste?
Answer: Farm waste constitutes animal wastes, which are regarded as an important source of soil fertility but also give rise to serious problems of odour and water pollution. Animal wastes enter water supplies when the runoff carries the wastes into water courses. Such wastes containing pathogenic organisms are ultimately transmitted to humans. Moreover, animal wastes cannot simply be treated as municipal sewage.
4. Define (i) overgrazing (ii) overcultivation (iii) desertification.
Answer:
(i) Overgrazing: Overgrazing refers to the excessive grazing of pasture in a given area by a great number of livestock.
(ii) Overcultivation: Overcultivation means continuous cultivation without allowing the land to remain free from cultivation for a certain period of time.
(iii) Desertification: Desertification is a process where the productive potential of a land decreases rapidly.
5. What is the difference between urban environment and natural environment?
Answer: The difference between urban environment and natural environment lies in the physical environment in urban areas, with its complex mix of built (Artificial) and natural elements. The urban environment might be considered the opposite of the natural environment since it concentrates so many people, buildings, and economic activities and their supporting infrastructure such as roads, water pipes, drains, and electricity and telephone systems. Larger cities, central business districts, downtown areas, and industrial estates may have little visible that can be associated with the natural environment. Human activities have radically shaped their environment, and they seem far removed from natural processes and resources. The other parts of the cities, however, seem less removed – for instance parks, greenbelts, rivers, coastlines, or residential areas with large gardens and plenty of open spaces. However, all urban centres remain dependent on natural resources and on natural processes for disposing of their wastes.
6. What are the effects of acid rain?
Answer:
(i) Acid rain corrodes metals.
(ii) Acid rain weathers stone buildings and monuments.
(iii) Acid rain injures and kills vegetation.
(iv) Acid rain acidifies lakes, streams, and soils.
7. Differentiate between migrant and floating population.
Answer:
Migrant population: Migration is the permanent or semi-permanent change in the residence of an individual person or group of people.
Floating population: Floating population refers to people who migrate to urban areas with the intention of eventually returning to their former home.
8. How do pesticides enter a food chain?
Answer: Pesticides enter a food chain by being taken in by plant eaters or absorbed directly through the skin by aquatic organisms such as fish and various invertebrates. The pesticide is further concentrated as it passes from herbivores (plant-eaters) to carnivores (meat-eaters). It becomes highly concentrated in the tissues of animals at the end of the food chain, such as peregrine falcon, bald eagle, and osprey. Chlorinated hydrocarbons interfere in the calcium metabolism of birds, causing thinning of eggshells and subsequent reproductive failure. As a result, some large predatory and fish-eating birds are almost on the verge of extinction.
Long Answer Questions
1. Discuss the stress on waste disposal methods due to increased human activities.
Answer: The stress on waste disposal methods due to increased human activities arises because human activities have increased and, in the course of meeting their own needs, they have been producing more and more waste. As a result, the usual methods of waste disposal like landfill, incineration, composting, resource recovery, and recycling are proving not very viable in light of the increased stress on waste disposal. Slums represent one of the worst types of environmental degradation, which have become concomitant to urbanisation and industrialisation. About 17% of India’s urban population lives in slums. National Building Organisation estimates reveal that in small and medium towns, slumdwellers comprise about 10%, while the figure is 20% for cities with populations between a lakh and a million, and about 31% for the largest cities. Delhi records the highest of 47.50% of slumdwellers. Amongst the states, Bihar has 37.50% of its urban population as slumdwellers, followed by Maharashtra with 32.63% and West Bengal with 31.53%. Kerala with 8.81% and Karnataka with 14.43% are the two states with the lowest percentage of urban population in slums. The slumdwellers live in environments with inadequate living space, water supply, and sewage facilities, causing steady deterioration of surrounding regions as well as human health.
2. How do chemical pollutants and physical hazards affect the health services?
Answer: Chemical pollutants and physical hazards affect health services by presenting environmental problems best identified in terms of the nature of the hazard. For instance, biological pathogens, chemical pollutants, and physical hazards challenge the health departments of various countries, especially with growing populations and new health problems arising from hitherto unknown pollutants. The most serious urban environmental problems worldwide in regard to health are biological pathogens (disease-causing agents) in urban water, food, air, and soil. Tens of millions of urban dwellers suffer each year from malaria or other diseases spread by insects, including hundreds of children under five who die due to these diseases. People of all ages suffer from intestinal parasitic infestations caused by pathogens in the soil, water, or food and from respiratory and other diseases caused or exacerbated by pathogens in the air, both indoors and outdoors. There is a large and growing list of chemical pollutants that are known to cause or contribute to ill health or premature death. Air pollution is sufficiently serious in many cities to have demonstrable health impacts. There is also a growing list of chemicals in the urban environment about which there is concern, even if the precise health impact is not known. Physical hazards are a major source of injury and premature death in most urban areas. Domestic accidents are often the most serious, especially if a high proportion of the population live in overcrowded dwellings made of flammable materials, as is common in many urban shanty towns. Road accidents are often among the most serious causes of injury and premature death.
3. How is stress on transport and air pollution connected?
Answer: Stress on transport and air pollution are connected because as most cities grow and more people settle in the suburbs, the use of both private and public transport has increased. More people needing transport to travel to and from their workplaces has led to the building of flyovers, highways, and train tunnels that have claimed land. Many times, these constructions have also encroached on the so-called ‘green belt’ areas in cities and towns. More vehicles have obviously led to more exhaust fume emissions that have polluted the air and caused health problems for many people. Providing transport facilities to a growing populace also results in stress on authorities to provide cheaper and more frequent transport services.
4. How has demand for housing increased in urban areas?
Answer: The demand for housing in urban areas has increased significantly over centuries. This demand was often met by unplanned additions and subdivisions of existing structures. Where climate permitted, squatting (occupying without title or payment of rent) became commonplace, but provided only temporary shelter. By the 19th century, with the Industrial Revolution, people were moving to cities in unprecedented numbers. Workers made their homes in sheds, railway yards, and factory cellars, typically without sanitation facilities or water supply. In the post-industrial society of the 20th century, housing in developing nations and poor parts of developed countries continues to be of insufficient quality and does not meet the demand of some parts of the population. Vacant, abandoned inner-city housing exists alongside structures that are usable but overcrowded, and buildings that are structurally reclaimable but functionally obsolete.
5. Why does urban population show fluctuation?
Answer: Urban population shows fluctuation due to migration and floating populations. Migration is the permanent or semi-permanent change in the residence of an individual person or group of people. It represents a spatial redistribution of people and can have important consequences for the use and development of land and other resources, living conditions, availability of jobs, and possibly political, social, and economic stability. In places like Nagaland, where people depend on agriculture for their livelihood and face unemployment due to a lack of industries, people migrate to different cities for better employment opportunities. People also send their children to big cities for higher education and training, becoming more aware of the benefits of a better life. In metropolitan cities of India and the world, migrants come in an effort to improve their lives, such as by securing better or more secure jobs or by improving their access to social amenities like schools or hospitals. They gradually settle down permanently in the cities. The floating population in urban areas includes people who migrate with the intention of eventually returning to their former home. Time scales can vary from years to even shorter periods. Such migrants include examples of labourers from Uttar Pradesh and Bihar who reach Punjab to earn a living during the farming season and later return to their home towns or villages.
6. How does use of inorganic fertilisers cause environmental problems in rural areas?
Answer: The use of inorganic fertilisers causes environmental problems in rural areas by transforming rural environments, especially in the 21st century, as governments have encouraged the adoption of modern varieties of crops and livestock together with the associated packages of external inputs (such as fertilisers, pesticides, antibiotics, credit, machinery) necessary to make these productive. Inorganic fertilisers, including nitrogen, phosphate, and potash, are now used on a large scale. When phosphates and nitrates are used carelessly, they may reach estuaries and lakes through runoffs, leading to algal blooms that choke whole stretches of water. This leads to the rotting of plants, depletion of oxygen, and death of fish. Even herbicides and insecticides used on farmland have been known to contaminate both surface and groundwater. Some of these pollutants are carried to distant places by wind, rain, and rivers, and have been found even in high mountains and seaside swamps. Fertilisers can be transmitted to groundwater by leaching and to surface waters by natural drainage and storm runoff. Nitrates are of prime concern since their presence in drinking water may cause methaemoglobinemia in infants, commonly known as ‘blue babies’. The same process occurs in the stomachs of ruminants, affecting livestock through nitrate poisoning. Plant nutrients also lead to eutrophication. The enrichment of water with nutrients is referred to as ‘eutrophication’. Plant nutrients, nitrogen, and phosphorus stimulate the growth of algae and other aquatic plants. Excessive growth of these plants and their subsequent decay produces bad odours and depletes the oxygen content of water.
7. What are the effects of use of synthetic pesticides?
Answer: The effects of the use of synthetic pesticides include disastrous environmental side-effects. Extensive use of synthetic pesticides derived from chlorinated hydrocarbons in pest control has led to persistent and resistant environmental degradation. These organochlorine pesticides are highly persistent and tend to resist biological degradation. Relatively insoluble in water, they cling to plant tissues and accumulate in the soil, at the bottom of streams and ponds, and in the atmosphere. Once volatilised, the pesticides are distributed worldwide, contaminating wilderness areas far removed from agricultural regions, even reaching the Antarctic and Arctic Zones. Although these synthetic chemicals are not found in nature, they nevertheless enter the food chain. The pesticides are either taken in by plant eaters or absorbed directly through the skin by aquatic organisms such as fish and various invertebrates. The pesticide becomes further concentrated as it passes from herbivores (plant-eaters) to carnivores (meat-eaters). It becomes highly concentrated in the tissues of animals at the end of the food chain, such as peregrine falcons, bald eagles, and ospreys. Chlorinated hydrocarbons interfere with the calcium metabolism of birds, causing thinning of eggshells and subsequent reproductive failure. As a result, some large predatory and fish-eating birds are almost on the verge of extinction. Because of the dangers of pesticides to wildlife and human beings, and because insects have acquired resistance to them, the use of halogenated hydrocarbons such as DDT is declining in the Western world, although large quantities are still used in developing countries.
8. What do you know about the degrading effect of pollution on the ozone layer?
Answer: The degrading effect of pollution on the ozone layer was discovered during the 1980s when scientists found that human activity was having a detrimental effect on the global ozone layer, a region of the atmosphere that shields the Earth from the sun’s harmful ultraviolet rays. Without this gaseous layer, no life is possible on Earth. Studies showed that the ozone layer is being damaged by the increasing use of industrial chemicals called chlorofluorocarbons (CFCs) that are extensively used in refrigeration, air-conditioning, cleaning solvents, packing materials, and aerosol sprays. Initially, it was believed that the ozone layer was being reduced gradually all over the globe. However, in 1985, further research revealed a growing ozone hole concentrated above Antarctica. Because of the growing threat of these dangerous environmental problems, many nations began working towards eliminating the manufacture and use of CFCs by the 2000s. However, CFCs remain in the atmosphere for more than 100 years, so ozone destruction will continue to pose a threat for decades to come.
Think and Answer
Has urbanisation proved to be a boon or a bane? Discuss in light of the effects on the environment.
Answer: Urbanisation has had both positive and negative effects on the environment, making it a subject of debate whether it is a boon or a bane. On one hand, urbanisation has led to economic growth, improved infrastructure, and better access to services such as healthcare and education. It has facilitated technological advancements and created numerous opportunities for employment and innovation. Urban areas often provide better living standards and have the potential to efficiently manage resources due to concentrated populations.
On the other hand, urbanisation has also caused significant environmental degradation. The expansion of urban areas has led to deforestation, loss of biodiversity, and the destruction of natural habitats. The increase in industrial activities and vehicular emissions has contributed to air and water pollution, making cities the epicentres of environmental hazards. The stress on waste disposal systems, inadequate housing, and the overuse of natural resources like water and land have resulted in severe environmental issues. Urban sprawl has also led to the encroachment on agricultural land, reducing the space available for food production and leading to problems like food insecurity.
Moreover, the concentration of populations in urban areas has led to the formation of slums, where people live in overcrowded and unsanitary conditions, further exacerbating environmental problems. The demand for housing, transportation, and energy in urban areas has increased the pressure on natural resources, leading to unsustainable consumption patterns. The environmental impact of urbanisation is further amplified by the generation of large amounts of waste and the challenges associated with its disposal.
Extras MCQs
1. Where did Homo sapiens first appear?
A. Asia
B. Europe
C. Africa
D. South America
Answer: C. Africa
31. What type of waste is classified as solid waste?
A. Liquids
B. Gases
C. Semi-solid materials
D. Energy
Answer: C. Semi-solid materials
Extra Questions and Answers
1. Where did human beings apparently first appear?
Answer: Human beings apparently first appeared in Africa.
49. How has the Industrial Revolution affected the environment?
Answer: The Industrial Revolution, which began in the mid-18th century, had profound effects on the environment. It marked a period of rapid technological advancement, leading to the discovery, use, and exploitation of fossil fuels and the extensive extraction of mineral resources. These activities significantly altered the Earth’s landscape, atmosphere, and water systems. The widespread use of fossil fuels, such as coal and oil, contributed to the release of large amounts of greenhouse gases and pollutants into the atmosphere, leading to global warming and air quality deterioration. The extraction of minerals disrupted natural ecosystems and depleted resources that had accumulated over millions of years. The Industrial Revolution set the stage for the modern era’s environmental challenges, including climate change, pollution, and resource depletion, which continue to impact the planet today.
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger. He manages Online Free Notes and reads Victorian literature. His favourite book is Wuthering Heights by Emily Bronte and he hopes to travel the world. Get in touch with him by sending him a friend request.
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