Read and download NCERT Class 12 Biology Environmental Issues in NCERT book for Class 12 Biology. You can download latest NCERT eBooks chapter wise in PDF format free from Studiestoday.com. This Biology textbook for Class 12 is designed by NCERT and is very useful for students. Please also refer to the NCERT solutions for Class 12 Biology to understand the answers of the exercise questions given at the end of this chapter
NCERT Book for Class 12 Biology Chapter 16 Environmental Issues
Class 12 Biology students should refer to the following NCERT Book Chapter 16 Environmental Issues in Class 12. This NCERT Book for Class 12 Biology will be very useful for exams and help you to score good marks
Chapter 16 Environmental Issues NCERT Book Class 12
ENVIRONMENTAL ISSUES
Introduction
Human population size has grown enormously over the last hundred years. This means increase in demand for food, water, home, electricity, roads, automobiles and numerous other commodities. These demands are exerting tremendous pressure on our natural resources, and arealso contributing to pollution of air, water and soil. The need of the hour is to check the degradation and depletion of our precious natural resources and pollution without halting the process of development. Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil. Agents that bring about such an undesirable change are called as pollutants. In order to control environmental pollution, the Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air, water and soil).
16.1 AIR POLLUTION AND ITS CONTROL
We are dependent on air for our respiratory needs. Air pollutants cause injury to all living organisms. They reduce growth and yield of crops and cause premature death of plants. Air pollutants also deleteriously affect the respiratory system of humans and of animals. Harmful effects depend on the concentration of pollutants, duration of exposure and the organism. Smokestacks of thermal power plants, smelters and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.
These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere. There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator (Figure 16.1), which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant. It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons.
These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall. A scrubber (Figure 16.1) can remove gases like sulphurdioxide. In a scrubber, the exhaust is passed through a spray of water or lime. Recently we have realised the dangers of particulate matter that are very very small and are not removed by these precipitators. According toCentral Pollution Control Board (CPCB), particulate size 2.5 micrometers or less in diameter (PM 2.5) are responsible for causing the greatest harm to human health. These fine particulates can be inhaled deep into the lungs and can cause breathing and respiratory symptoms, irritation, inflammations and damage to the lungs and premature deaths.
EXERCISES
1. What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
2. List all the wastes that you generate, at home, school or during your trips to other places, could you very easily reduce? Which would be difficult or rather impossible to reduce?
3. Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
4. Match the items given in column A and B: Column A Column B
(a) Catalytic converter (i) Particulate matter
(b) Electrostatic precipitator (ii) Carbon monoxide and nitrogen oxides
(c) Earmuffs (iii) High noise level
(d) Landfills (iv) Solid wastes
5. Write critical notes on the following:
(a) Eutrophication
(b) Biological magnification
(c)Groundwater depletion and ways for its replenishment
6. Why ozone hole forms over Antarctica? How will enhanced ultraviolet radiation affect us?
7. Discuss the role of women and communities in protection and conservation of forests.
8. What measures, as an individual, you would take to reduce environmental pollution?
9. Discuss briefly the following:
(a) Radioactive wastes
(b) Defunct ships and e-wastes
(c) Municipal solid wastes
10. What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
11. Discuss briefly the following :
(a) Greenhouse gases
Please refer to attached file for NCERT Class 12 Biology Environmental Issues
NCERT Class 12 Biology Reproduction in Organisms |
NCERT Class 12 Biology Sexual Reproduction in Flowering Plants |
NCERT Class 12 Biology Human Reproduction |
NCERT Class 12 Biology Reproductive Health |
NCERT Class 12 Biology Principles of Inheritance |
NCERT Class 12 Biology Molecular Basis of Inheritance |
NCERT Class 12 Biology Evolution |
NCERT Class 12 Biology Human Health and Disease |
NCERT Class 12 Biology Strategies For Enhancement in Food Reproduction |
NCERT Class 12 Biology Microbes In Human Welfare |
NCERT Class 12 Biology Biotechnology Principles and Processes |
NCERT Class 12 Biology Biotechnology and Its Applications |
NCERT Class 12 Biology Organisms and Populations |
NCERT Class 12 Biology Ecosystem |
NCERT Class 12 Biology Biodiversity and Conservation |
NCERT Class 12 Biology Environmental Issues |
NCERT Book Class 12 Biology Chapter 16 Environmental Issues
The above NCERT Books for Class 12 Biology Chapter 16 Environmental Issues have been published by NCERT for latest academic session. The textbook by NCERT for Chapter 16 Environmental Issues Biology Class 12 is being used by various schools and almost all education boards in India. Teachers have always recommended students to refer to Chapter 16 Environmental Issues NCERT etextbooks as the exams for Class 12 Biology are always asked as per the syllabus defined in these ebooks. These Class 12 Chapter 16 Environmental Issues book for Biology also includes collection of question. Along with Biology Class 12 NCERT Book in Pdf for Chapter 16 Environmental Issues we have provided all NCERT Books in English Medium for Class 12 which will be really helpful for students who have opted for english language as a medium. Class 12 students will need their books in English so we have provided them here for all subjects in Class 12.
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