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Biology · Class 12 Science

Ch 14Environmental Issues — Class 12 Biology, concept-first.

Environmental issues today span an enormous range -- from the pollution of air and water to the loss of forests and species -- but the WBCHSE Class XII syllabus asks students to focus closely on two connected themes for this chapter: how modern societies manage the waste they generate, and how ordinary people, acting o…

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Key concepts

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Solid Waste Management

Solid waste management deals with everything discarded as trash — municipal solid waste from homes, offices, shops, schools and hospitals, typically comprising paper, food waste, plastics, glass, metals, rubber, leather…

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Chapter contents

The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.

14.1

Environmental Issues: Waste and Conservation -- An Overview

Environmental issues today span an enormous range -- from the pollution of air and water to the loss of forests and species -- but the WBCHSE Class XII syllabus asks students to focus closely on two c…

14.2

Solid Waste: Sources and the 3R Principle

Solid waste refers to any discarded solid or semi-solid material that results from human activities and that its original owner no longer wants or needs.

14.3

Solid Waste Management Methods: Segregation, Composting and Landfills

Once solid waste has been generated, how it is actually collected, sorted and disposed of determines whether it becomes a manageable resource or an accumulating environmental hazard.

14.4

E-waste: A Growing Modern Concern

Electronic waste, or e-waste, refers to discarded electrical and electronic equipment -- computers and laptops, mobile phones, televisions, refrigerators and other household appliances, printers, and…

14.5

Radioactive Waste: Sources and Half-life

Radioactive waste is material -- solid, liquid or gaseous -- that contains radioactive isotopes (unstable atomic nuclei that spontaneously emit ionising radiation as they decay toward a more stable fo…

14.6

Radioactive Waste Management and Disposal

Because radioactive waste cannot be chemically treated to remove its hazard, its management is fundamentally a problem of safe, reliable containment and isolation for however long it takes for natural…

14.7

People's Movements for Environmental Conservation: An Overview

Alongside the technical systems used to manage solid and radioactive waste, India has a long and distinctive history of a different kind of environmental protection: grassroots, people-led movements i…

14.8

The Amrita Devi Bishnoi Movement

The Amrita Devi Bishnoi movement is the earliest of the four grassroots conservation episodes named in the WBCHSE syllabus, and its events are traditionally dated to around 1730, at the village of Khe…

14.9

The Chipko Movement and the Dasholi Gram Swarajya Mandal (DGSM)

The Chipko Movement is probably the best known of India's grassroots forest conservation movements, and it emerged in the early 1970s in the Garhwal region of the Himalayas, in what was then part of U…

14.10

The Silent Valley Movement

Silent Valley is a tract of largely untouched tropical evergreen rainforest located in the Palakkad district of Kerala, within the Western Ghats -- one of the world's recognised biodiversity hotspots.…

Summary

This chapter examined two connected aspects of environmental issues specifically named in the WBCHSE Class XII syllabus: the management of waste generated by modern human activity, and the history of…

Sample & Board Papers

Sample papers and previous-year board questions for this subject.

+Show 6 questions6 questions
  1. Q1Which of the following is a secondary air pollutant? (a) Aerosol (b) PAN (c) CO2 (d) COPreview
  2. Q2What do you mean by Greenhouse effect? What are the different ways by which Global Warming takes place? (2+3)Preview
  3. Q3Which one of the following are greenhouse gases? (a) CO2, CFC, CH4, N2O (b) CO2, NO2, NH3, N2O (c) CH4, N2, NH3, CO2 (d) CFC, CO2, N2O, NH3Preview
  4. Q4Mention any two reasons for creation of Ozone hole. What is Electrostatic Precipitator?Preview
  5. Q5An example of secondary air pollutant is (a) Sulphur dust (b) Aromatic hydrocarbon (c) CO (d) Peroxyacetyl nitrate (PAN)Preview
  6. Q6i) What is radioactive waste? Mention two sources that generate radioactive waste. ii) ‘No two species can have exactly the same niche.’ — J…Preview

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32 Q
+Show 6 questions6 questions
  1. Q1What is solid waste? List the major sources of solid waste generated in a typical Indian urban household and city.Free
  2. Q2Explain what is meant by segregation of solid waste at source. Why is separating waste into biodegradable, non-biodegradable and recyclable…Free
  3. Q3Describe composting as a method of managing biodegradable solid waste. What products are formed, and how are they useful?Preview
  4. Q4What is vermicomposting? Explain briefly how earthworms are used in this process and mention one advantage it has over ordinary composting.Preview
  5. Q5Describe a sanitary landfill as a method of solid waste disposal. Mention two problems associated with poorly managed, open dumping sites.Preview
  6. Q6Discuss the public health and environmental hazards that arise when municipal solid waste is not properly collected, segregated and disposed…Preview
+Show 2 questions2 questions
  1. Q7Explain the 3R principle of waste management -- Reduce, Reuse and Recycle -- giving one everyday example of each.Free
  2. Q8Among Reduce, Reuse and Recycle, which is generally considered the most preferred approach and why?Preview
+Show 3 questions3 questions
  1. Q9What is e-waste? Name the main sources that contribute to the growing e-waste problem in India.Free
  2. Q10What health and environmental hazards can result from the unscientific, informal recycling of e-waste (for example, open burning of circuit…Preview
  3. Q11Suggest two measures that can help manage e-waste safely and reduce its environmental impact.Preview
+Show 6 questions6 questions
  1. Q12What is radioactive waste? Name the major sources that generate radioactive waste.Free
  2. Q13Explain the concept of half-life of a radioactive substance and state why this concept is important while planning the safe storage of radio…Free
  3. Q14Radioactive waste is often classified as low-level, intermediate-level and high-level waste. Briefly distinguish between these categories.Preview
  4. Q15What is meant by vitrification of high-level radioactive waste? Why is this technique used?Preview
  5. Q16What is deep geological disposal of radioactive waste? Why is this considered a safer long-term option than simple surface storage?Preview
  6. Q17Discuss the health hazards associated with exposure to radioactive waste and why its containment must be maintained for very long periods.Preview
+Show 4 questions4 questions
  1. Q18Give a brief historical account of the Amrita Devi Bishnoi movement -- when and where it is traditionally said to have taken place, and what…Free
  2. Q19Who was Amrita Devi, and what did she do to try to protect the Khejri trees of her village?Free
  3. Q20The Bishnoi community's way of life places great emphasis on protecting trees and wildlife. Briefly describe this aspect of Bishnoi traditio…Preview
  4. Q21In what way is the Amrita Devi Bishnoi movement considered an early forerunner of the tree-hugging tactic later associated with the Chipko m…Preview
+Show 4 questions4 questions
  1. Q22What does the word 'Chipko' mean, and what specific method of protest gave the Chipko Movement its name?Free
  2. Q23In which region of India did the Chipko Movement originate, and around which decade did it become prominent?Free
  3. Q24Describe the role played by local women, such as Gaura Devi and the women of Reni village, in the Chipko Movement.Preview
  4. Q25What was the broader outcome and significance of the Chipko Movement for forest conservation policy in India?Preview
+Show 3 questions3 questions
  1. Q26What is the Dasholi Gram Swarajya Mandal (DGSM), and in which area of Uttarakhand was it based?Free
  2. Q27Explain the role of the Dasholi Gram Swarajya Mandal, associated with Chandi Prasad Bhatt, in giving rise to the Chipko Movement.Preview
  3. Q28Why is a local cooperative organisation like DGSM considered important for grassroots environmental conservation, beyond just the specific C…Preview
+Show 4 questions4 questions
  1. Q29Where is Silent Valley located, and what made this forest ecologically significant?Free
  2. Q30What development project was proposed for Silent Valley, and why did it lead to widespread protest?Free
  3. Q31Which organisations and forms of protest were associated with the Silent Valley movement?Preview
  4. Q32What was the eventual outcome of the Silent Valley movement, and what is the area's conservation status today?Preview