Botany · Class 12 Science
Ch 8Environmental Issues — Class 12 Botany, concept-first.
Clean air is essential for every living organism, and once it becomes contaminated with pollutants it can injure plants, slow crop growth and yield, and damage the respiratory systems of humans and animals.
Key concepts
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Sewage Treatment
Sewage treatment addresses domestic wastewater, which — although only about 0.1% impurities by mass — is unfit for human use and, if discharged untreated, depletes dissolved oxygen in receiving water bodies (causing fish…
Most relevant Q&A
Chapter contents
The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.
Air Pollution and Its Control
Clean air is essential for every living organism, and once it becomes contaminated with pollutants it can injure plants, slow crop growth and yield, and damage the respiratory systems of humans and an…
Controlling Vehicular Air Pollution: A Case Study of Delhi
Delhi has one of the largest vehicle populations of any Indian city — at one point it had more registered vehicles than the states of Gujarat and West Bengal combined — and by the 1990s it ranked amon…
Water Pollution and Its Control
Across the world, human beings have long treated rivers, lakes and other water bodies as convenient places to dispose of waste, on the mistaken assumption that flowing water simply "washes everything…
Domestic Sewage and Industrial Effluents
Wastewater from homes carries away everything we wash down our drains, yet it takes only about 0.1 per cent impurity by mass to make domestic sewage unfit for human use — a striking illustration of ho…
A Case Study of Integrated Waste Water Treatment
Wastewater treatment does not have to rely purely on engineered, artificial processes — it can also combine artificial treatment with natural, ecosystem-based processes, and the town of Arcata on the…
Solid Wastes
Solid wastes are, quite simply, everything that ends up in the trash. Municipal solid waste is the waste generated by homes, offices, shops, schools and hospitals that a municipality collects and disp…
Case Study of Remedy for Plastic Waste
A Bangalore-based manufacturer of plastic sacks found a practical answer to the growing problem of plastic waste piling up in the city.
Agro-chemicals and their Effects
The Green Revolution brought a large rise in the use of inorganic (chemical) fertilisers along with pesticides, herbicides and fungicides, all aimed at boosting crop yields.
Case Study of Organic Farming
Integrated organic farming is a cyclical, essentially zero-waste approach to agriculture, in which the waste generated by one process becomes the input — the nutrient supply — for another.
Radioactive Wastes
Nuclear power was originally welcomed as a clean, non-polluting way of generating electricity. Over time, however, two serious problems associated with it became clear: the risk of accidental leakage…
Greenhouse Effect and Global Warming
The term borrows its name from an actual greenhouse — a small glass structure used to grow plants, especially through winter.
Ozone Depletion in the Stratosphere
Ozone formed near the ground, in the troposphere, is a harmful pollutant that damages plants and animals — this is the "bad" ozone studied earlier in chemistry.
Degradation by Improper Resource Utilisation and Maintenance
Natural resources can be degraded not only by pollution but also simply by using and managing them poorly.
Deforestation
Deforestation is the conversion of forested land into land that no longer carries forest cover. Globally, an estimated 40 per cent of tropical forest has already been lost, compared with only about 1…
Case Study of People's Participation in Conservation of Forests
People's involvement in forest protection in India has deep historical roots. In 1731, the king of Jodhpur in Rajasthan sent his minister and workers to fell trees near a village inhabited by the Bish…
Exercises
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- Q1What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.Free
- Q2List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of…Free
- Q3Discuss the causes and effects of global warming. What measures need to be taken to control global warming?Free
- Q4Match the items given in column A and B: Column A Column B (a) Catalytic converter (i) Particulate matter (b) Electrostatic precipitator (ii…Preview
- Q5Write critical notes on the following: (a) Eutrophication (b) Biological magnification (c) Groundwater depletion and ways for its replenishm…Preview
- Q6Why does ozone hole form over Antarctica? How will enhanced ultraviolet radiation affect us?Preview
- Q7Discuss the role of women and communities in protection and conservation of forests.Preview
- Q8What measures, as an individual, would you take to reduce environmental pollution?Preview
- Q9Discuss briefly the following: (a) Radioactive wastes (b) Defunct ships and e-wastes (c) Municipal solid wastesPreview
- Q10What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?Preview
- Q11Discuss briefly the following: (a) Greenhouse gases (b) Catalytic converter (c) Ultraviolet BPreview