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Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download: Tamil Nadu STD 12th Bio Botany Chapter 8 Environmental Issues Notes

Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download: Tamil Nadu STD 12th Bio Botany Chapter 8 Environmental Issues Notes
Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download: Tamil Nadu STD 12th Bio Botany Chapter 8 Environmental Issues Notes

Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download: Students of class can download the Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download from our website. We have uploaded the Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues notes according to the latest chapters present in the syllabus. Download Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Chapter Wise Notes PDF from the links provided in this article.

Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF Download

We bring to you specially curated Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF which have been prepared by our subject experts after carefully following the trend of the exam in the last few years. The notes will not only serve for revision purposes, but also will have several cuts and easy methods to go about a difficult problem.


Tamilnadu Board

Study Material



Samacheer Kalvi 12th Bio Botany


12th Bio Botany


Chapter 8 Environmental Issues




Samacheer Kalvi Books

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Samacheer Kalvi 12th Bio Botany Environmental Issues Text Book Back Questions and Answers

Question 1. Which of the following would most likely help to slow down the greenhouse effect?
(a) Converting tropical forests into grazing land for cattle. (b) Ensuring that all excess paper packaging is buried to ashes. (c) Redesigning landfill dumps to allow methane to be collected. (d) Promoting the use of private rather than public transport.
Answer: (d) Promoting the use of private rather than public transport.

Question 2. With respect to Eichhornia Statement A: It drains off oxygen from water and is seen growing in standing water. Statement B: It is an indigenous species of our country.
(a) Statement A is correct and Statement B is wrong. (b) Both Statements A and B are correct. (c) Statement A is correct and Statement B is wrong. (d) Both statements A and B are wrong.
(a) Statement A is correct and Statement B is wrong.

Question 3. Find the wrongly matched pair.
(a) Endemism – Species confined to a region and not found anywhere else. (b) Hotspots – Western ghats (c) Ex-situ Conservation – Zoological parks (d) Sacred groves – Saintri hills of Rajasthan (e) Alien sp Of India – Water hyacinth
Answer: (d) Sacred groves – Saintri hills of Rajasthan

Question 4. Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancer?
(a) Ammonia (b) Methane (c) Nitrous oxide (d) Ozone
Answer: (d) Ozone

Question 5. One green house gas contributes 14% of total global warming and another contributes 6%. These are respectively identified as ________
(a) N2O and CO2 (b) CFCs and N2O (c) CH4 and CO2 (d) CH4 and CFCS
Answer: (b) CFCs and N2O

Question 6. One of the chief reasons among the following for the depletion in the number of species making endangered is ______
(a) over hunting and poaching (b) green house effect (c) competition and predation (d) habitat destruction
Answer: (d) habitat destruction

Question 7. Deforestation means ______
(a) growing plants and trees in an area where there is no forest (b) growing plants and trees in an area where the forest is removed (c) growing plants and trees in a pond (d) removal of plants and trees
Answer: (d) removal of plants and trees

Question 8. Deforestation does not lead to _______
(a) Quick nutrient cycling (b) Soil erosion (c) alternation of local weather conditions (d) Destruction of natural habitat weather conditions
(a) Quick nutrient cycling

Question 9. The unit for measuring ozone thickness ______
(a) Joule (b) Kilos (c) Dobson (d) Watt
Answer: (c) Dobson

Question 10. People’s movement for the protection of environment in Sirsi of Karnataka is ________
(a) Chipko movement (b) Amirtha Devi Bishwas movement (c) Appiko movement (d) None of the above
Answer: (c) Appiko movement

Question 11. The plants which are grown in silivpasture system are ________
(a) Sesbania and Acacia (b) Solenum and Crotalaria (c) Clitoria and Begonia (d) Teak and sandal
(a) Sesbania and Acacia

Question 12. What is ozone hole?
Answer: The decline in the thickness of the ozone layer over restricted area is called Ozone hole.

Question 13. Give four examples of plants cultivated in commercial agroforestry.
Answer: Casuarina, Eucalyptus, Teak, Malai vembu.

Question 14. Expand CCS.
Answer: Carbon Capture and Storage.

Question 15. Hpw do forests help in maintaining the climate?
Answer: Forests play a major role in regulating the CO2 level in the atmosphere. As the result global warming in highly reduced.

Question 16. How do sacred groves help in the conservation of biodiversity?
Answer: These are the patches or grove of cultivated trees which are community protected and are based on strong religious belief systems which usually have a significant religious connotation for protecting community. Each grove is an abode of a deity mostly village God Or Goddesses like Aiyanar or Amman.

448 grooves were documented throughout Tamil Nadu, of which 6 groves (Banagudi shola, Thirukurungudi and Udaiyankudikadu, Sittannnavasal, Puthupet and Devadanam) were taken up for detailed floristic and faunistic studies. These groves provide a number of ecosystem services to the neighbourhood like protecting watershed, fodder, medicinal plants and micro climate control.

Question 17. Which one gas is most abundant out of the four commonest greenhouse gases? Discuss the effect of this gas on the growth of plants?
Answer: Carbondioxide is the most abundant greenhouse gas. Increase in CO2 level in the air decreases the uptake of nitrogen components leading to protein deficiency and chlorophyll formation.

Question 18. Suggest a solution to water crisis and explain its advantages.
Answer: Rainwater harvesting is the accumulation and storage of rain water for reuse in-site rather than allowing it to run off. Rainwater can be collected from rivers, roof tops and the water collected is directed to a deep pit. The water percolates and gets stored in the pit. RWH is a sustainable water management practice implemented not only in urban area but also in agricultural fields, which is an important economical cost effective method for the future. Environmental benefits of Rain Water Harvesting:

  1. Promotes adequacy of underground water and water conservation.
  2. Mitigates the effect of drought.
  3. Reduces soil erosion as surface run-off is reduced.
  4. Reduces flood hazards.
  5. Improves groundwater quality and water table / decreases salinity.
  6. No land is wasted for storage purpose and no population displacement is involved.
  7. Storing water underground is an eco-friendly measure and a part of sustainable water storage strategy for local communities.

Question 19. Explain afforestation with case studies.
Answer: Afforestation is planting of trees where there was no previous tree coverage and the conversion of non-forested lands into forests by planting suitable trees to retrieve the vegetation. Example: Slopes of dams afforesed to reduce water run-off, erosion and siltation. It can also provide a range of environmental sendees including carbon sequestration, water retention. The Man who Single Handedly Created a Dense Forest

Jadav “Molai” Payeng (bom 1963) is an environmental activist has single-handedly planted a forest in the middle of a barren wasteland. This Forest Man of India has transformed the world’s largest river island, Majuli, located on one of India’s major rivers, the Brahmaputra, into a dense forest, home to rhinos, deers, elephants, tigers and birds. And today his forest is larger than Central Park.

Former vice-chancellor of Jawahar Lai Nehru University, Sudhir Kumar Sopory named Jadav Payeng as Forest Man of India, in the month of October 2013. He was honoured at the Indian Institute of Forest Management during their annual event Coalescence. In 2015, he was honoured with Padma Shri, the fourth highest civilian award in India. He received honorary doctorate degree from Assam Agricultural University and Kaziranga University for his contributions.

Question 20. What are the effects of deforestation and benefits of agroforesty?
Answer: Effects of deforestation:

  1. Burning of forest wood release stored carbon, a negative impact just opposite of carbon sequestration.
  2. Trees and plants bind the soil particles. The removal of forest cover increases soil erosion and decreases soil fertility. Deforestation in dry areas leads to the formation of deserts.
  3. The amount of runoff water increases soil erosion and also creates flash flooding, thus reducing moisture and humidity.
  4. The alteration of local precipitation patterns leading to drought conditions in many regions. It triggers adverse climatic conditions and alters water cycle in ecosystem.
  5. It decreases the bio-diversity significantly as their habitats are disturbed and disruption of natural cycles.
  6. Loss of livelihood for forest dwellers and rural people.
  7. Increased global warming and account for one-third of total CO2 emission.
  8. Loss of life support resources, fuel, medicinal herbs and wild edible fruits.

Benefits of agroforestry:

  1. It is an answer to the problem of soil and water conservation and also to stabilise the soil (salinity and water table) reduce landslide and water run-off problem.
  2. Nutrient cycling between species improves and organic matter is maintained.
  3. Trees provide micro climate for crops and maintain CO2 balanced, atmospheric temperature and relative humidity.
  4. Suitable for dry land where rainfall is minimum and hence it is a good system for alternate land use pattern.
  5. Multipurpose tree varieties like Acacia are used for wood pulp, tanning, paper and firewood – industries.
  6. Agro-forestry is recommended for the following purposes. It can be used as Farm Forestry for the extension of forests, mixed forestry, shelter belts and linear strip plantation.

Samacheer Kalvi 12th Bio Botany Environmental Issues Additional Questions and Answers

1 – Mark Questions

Question 1. Which is not a green house gas?
(a) CO2 (b) N2O (c) O3 (d) CFC
Answer: (C) O3

Question 2. Identify the incorrect statement with regard to Global warming.
(a) Leads to species enrichment (b) Decreases irrigation (c) Increases vector population (d) Frequent heat waves
(a) Leads to species enrichment

Question 3. __________ is the unit of measurement of total ozone.
Answer: Dobson unit

Question 4. The total ozone layer over the earth surface is __________
(a) 30 DU (b) 300 DU (c) 3000 DU (d) 0.3 DU
Answer: (b) 300 DU

Question 5. Methane is __________ times as effective as CO2 at trapping heat.
(a) 5 (b) 10 (c) 20 (d) 100
Answer: (b) 20

Question 6. Which is not a beneficial aspect of Agroforestry?
(a) Nutrient cycling is improved (b) Balance in O2 – CO2 composition (c) Suitable for wet land where rainfall is maximum (d) Reduces water run-off problem
Answer: (c) Suitable for wet land where rainfall is maximum

Question 7. The production of woody plants combined with pasture is referred to system.
Answer: Silvopasture

Question 8. Assertion
(a): CO2 is a main cause for global warming Reason (R) : Greenhouse gases trap the radiant heat from sun
(a) A is correct R is incorrect. (b) A is incorrect R is correct. (c) R explains A. (d) Both A and R are incorrect.
Answer: (c) R explains A.

Question 9. Assertion
(a): Ozone acts as a natural sun block. Reason (R): UV rays reaching the earth are deviated from earth.
(a) A is correct R is incorrect. (b) A is incorrect R is correct. (c) R explains A. (d) Both A and R are incorrect.
Answer: (c) R explains A.

Question 10. Assertion
(a): Social forestry refers to management of forests and afforestation on barren lands. Reason (R): Afforestation involves the cutting of trees.
(a) A is correct R is incorrect. (b) A is incorrect R is correct. (c) R explains A. (d) Both A and R are incorrect.
(a) A is correct R is incorrect.

Question 11. Assertion
(a): Prosopis juliflora is native to Afganisthan. Reason (R): Alien species refers to non-native species.
(a) A is correct R is incorrect. (b) A is incorrect R is correct. (c) R explains A. (d) Both A and R are incorrect.
Answer: (b) A is incorrect R is correct.

Question 12. Assertion
(a): In zoological parks, the animals are maintained in their natural habitat. Reason (R): Ex-situ conservation refers to protecting species in their natural habitat.
(a) A is correct R is incorrect. (b) A is incorrect R is correct. (c) R explains A. (d) Both A and R are incorrect.
Answer: (d) Both A and R are incorrect.

Question 13. Which is not reduced by deforestation?
(a) Amount of habitat (b) Amount of animal population (c) Amount of biodiversity (d) Amount of agricultural land
Answer: (d) Amount of agricultural land

Question 14. Identify the potent cause for deforestation.
(a) Agriculture (b) Soil erosion (c) Afforestation (d) Forest fire
(a) Agriculture

Question 15. Total number of forestry extension centres in Tamil Nadu is __________
(a) 16 (b) 32 (c) 18 (d) 51
Answer: (b) 32

Question 16. Who is celebrated as Forest Man of India?
(a) Anand Mohan Chakrabarthy (b) Dr. M.S Swaminathan (c) Jadav Molai Payeng (d) Choudary Ram Dhan
Answer: (c) Jadav Molai Payeng

Question 17. Invasive species __________
(a) alter the soil system (b) are more adapted (c) are fast growing (d) all the above
Answer: (d) all the above

Question 18. Pick out the odd one out __________
(a) Biosphere reserve (b) National Park (c) Wild life sanctuaries (d) Botanical gardens
Answer: (d) Botanical gardens

Question 19. Which is not true with respect to prosopis juliflora?
(a) Invasive species native to Mexico (b) Arrest wind erosion (c) Absorb hazardous chemical from soil (d) Decreases O2 content of water bodies
Answer: (d) Decreases O2 content of water bodies

Question 20. How many numbers of scared grooves were documented in tamil nadu?
(a) 484 (b) 844 (c) 488 (d) 448
Answer: (c) 488

Question 21. Match the following:
Samacheer Kalvi 12th Bio Botany Solutions Chapter 8 Environmental Issues
(a) A – iii, B – iv, C – i, D – ii

Question 22. Process of heating biomass in low oxygen environment is called as ______
Answer: Pyrolysis

Question 23. Biochar is __________ (i) a kind of char coal used as a soil amendment (ii) a potent way of sequestring carbon (iii) made from biomass via pyrolysis (iv) a notable solid, rich in carbon.
(a) (i) and (iii) is correct (b) (ii) and (iv) is correct (c) (i) and (ii) is correct (d) all the above is correct.
Answer: (d) all the above is correct.

Question 24. Which is not a true statement regarding rain water harvesting?
(a) Mitigates groundwater quality (b) Reduces soil erosion (c) Decreases soil salinity (d) No wastage of land for storing
(a) Mitigaes groundwater quality

Question 25. EIA stands for __________
(a) Ecological Information Analysis (b) Environmental Information Assessment (c) Environmental Impact Analysis (d) Environmental Impact Assessment
Answer: (d) Environmental Impact Assessment

Question 26. __________ is the 100th Satellite launched to watch border surveillance.
Answer: (d) CARTOSAT-2

Question 27. The ozone layer of __________ is called bad ozone.
(a) Stratosphere (b) Mesosphere (c) Troposphere (d) Exosphere
Answer: (c) Troposhere

Question 28. When does World Ozone Day is observed?
(a) June 17th (b) December 1st (c) October 12th (d) September 16th
Answer: (d) September 16th

Question 29. Clean Development Mechanism (CDM) is defined in __________
(a) Copenhagen Acord (b) Montreal Protocol (c) Paris Agreement (d) Kyoto Protocol
Answer: (d) Kyoto Protocol

Question 30. __________ is a plant species which acts as an indicator of Nitrate pollution.
(a) Petunia (b) Lichens (c) Gladiolus (d) Pinus
(a) Petunia

Question 31. Identify the plant species that is not used as a live fence.
(a) Sesbania grandiflora (b) Acacia species (c) Petunia species (d) Erythrina species
Answer: (c) Petunia species

Question 32. Match the following:
Samacheer Kalvi 12th Bio Botany Solutions Chapter 8 Environmental Issues
(a) A – iv, B – iii, C – ii, D – i

2 – Mark Questions

Question 1. What are greenhouse gases? Give an example.
Answer: The gases that capture heat are called Green House Gases. E.g: Carbon dioxide (CO2)

Question 2. Name any four green house gases.
Answer: CO2, CH4, N2O and CFC

Question 3. Define global warming.
Answer: The increase in mean global temperature due to increased concentration of green house gases is called global warming.

Question 4. Methane is one of a potent green house gas. Point out few sources from where methane is generated.
Answer: Paddy field, fossil fuel production, bacteria in water bodies, cattle rearing, non-wetland soils and forest & wild fires.

Question 5. List out the anthropogenic sources of Nitrous oxide.
Answer: Man-made sources include nylon and nitric acid production, use of fertilizers in agriculture, manures cars with catalytic converter and burning of organic matter.

Question 6. What is Dobson unit?
Answer: Dobson Unit is the unit of measurement for total ozone. One DU is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimetre thick at a temperature of 0° C and a pressure of 1 atmosphere.

Question 7. What do you mean by good ozone and bad ozone?

  1. The ozone layer of troposphere is called bad ozone.
  2. The ozone layer of stratosphere is called good ozone.

Question 8. What is ozone layer? Why it is essential?
Answer: Ozone layer is a region of Earth’s stratosphere that absorbs most of the Sim’s ultra violet radiation. The ozone layer is also called as the ozone shield and it acts as a protective shield, cutting the ultra-violet radiation emitted by the sun.

Question 9. Define ozone hole. Name any one potent chemical that is responsible for the effect.
Answer: The decline in the thickness of the ozone layer over restricted area is called Ozone hole. Chlorofluorocarbons (CFC) damages the ozone layer to a great extent.

Question 10. Where did Montreal Protocol was held? State its objectives.
Answer: The International treaty called the Montreal Protocol (1987) was held in Canada on substances that deplete ozone layer and the main goal of it is gradually eliminating the production and consumption of ozone depleting substances and to limit their damage on the Earth’s ozone layer.

Question 11. What is meant by biological indicators? Give example.
Answer: The plant species or plant community acts as a measure of environmental conditions, it is referred as biological indicators or phytoindicators or plant indicators. E.g: Lichens as SO2 pollution indicator.

Question 12. Name the plant species which act as indicators for Nitrate pollution & Flouride pollution.

  1. Petunia species acts as indicators for Nitrate pollution.
  2. Gladiolus species acts as indicators for Flouride pollution.

Question 13. Define the term Agroforestry. Name any two major tree species cultivated in Agroforestry.
Answer: Agroforestry is an integration of trees, crops and livestock on the name plot of land. The commercial Agroforestry trees are casuarina and Eucalyptus.

Question 14. What is silvopasture system? How it helps economy?
Answer: The production of woody plants combined with pasture is referred to silvopasture system. The trees and shrubs may be used primarily to produce fodder for livestock or they may be grown for timber, fuel wood and fruit or to improve the soil.

Question 15. Mention the name of any four plant species that are widely used as live fences in agricultural practicer.

  1. Gliricidia sepium
  2. Sesbaniagrandiflora
  3. Erythrina species
  4. Acacia species

Question 16. Define social forestry.
Answer: Social forestry refers to the management of forests and afforestation on barren lands with the purpose of helping the environmental, social and rural development and benefits.

Question 17. Compare Deforestation and Afforestation

  1. Deforestation: The conversion of forested area into a non- forested area is known as deforestation.
  2. Afforestation: Afforestation is planting of trees where there was no previous tree coverage and the conversion of non-forested lands into forests by planting suitable trees to retrieve the vegetation.

Question 18. What is invasive species?
Answer: A non-native species to the ecosystem or country under consideration that spreads naturally, interferes with the biology and existence of native species, poses a serious threat to the ecosystem and causes economic loss

Question 19. Point out the adverse effect caused by invasive species.
Answer: Invasive species are fast growing and are more adapted. They alter the soil system by changing litter quality thereby affecting the soil community, soil fauna and the ecosystem processes. It has a negative impact on decomposition in the soils by causing stress to the neighbouring native species.

Question 20. Distinguish between In-situ conservation and Ex-situ conservation.
Answer: In-situ conservation:

  1. Conservation of species in their natural habitat.
  2. E.g: Biosphere reserves

Ex-situ conservation:

  1. Conservation of species outside their natural habitat.
  2. E.g: Zoological parks

Question 21. Mention any two historical community level conservation movements held for the protection of environment.
Answer: Chipko Movement and Appiko Movement

Question 22. Give the names of any four famous sacred grooves in Tamil Nadu.

  1. Banagudi Shola
  2. Thirukurungudi
  3. Udaiyankudikadu
  4. Sittannavasal

Question 23. What does the term ‘Endemic’ refers to?
Answer: Any species found restricted to a specified geographical area is referred to as ENDEMIC.

Question 24. Name any two endemic trees of Peninsular India.

  1. Agasthiyamalaia pauciflora
  2. Harawickia binata

Question 25. What is carbon sequestration?
Answer: Carbon sequestration is the process of capturing and storing CO2 which reduces the amount of CO2 in the atmosphere with a goal of reducing global climate change.

Question 26. Carbon sequestration occurs naturally by plants and oceans. Name any four microalgal species involved in the process.

  1. Chlorella
  2. Scenedesmus
  3. Chroococcus
  4. Chlamydomonas

Question 27. Explain the term Carbon sink.
Answer: Any system having the capacity to accumulate more atmospheric carbon during a given time interval than releasing CO2. Example: forest, soil, ocean are natural sinks. Landfills are artificial sinks.

Question 28. How EIA is beneficial to a society? The benefits of EIA to society

  1. A healthier environment
  2. Maintenance of biodiversity
  3. Decreased resource usage
  4. Reduction in gas emission and environment damage

Question 29. What is GIS?
Answer: Geographic Information System (GIS) is a computer system for capturing, storing, checking and displaying data related to positions on Earth’s surface. Also to manipulate, analyse, manage and present spacial or geographic data.

3 – Mark Questions

Question 30. List out the effects of global warming.

  1. Rise in global temperature which causes sea levels to rise as polar ice caps and glaciers begin to melt causing submergence of many coastal cities in many parts of the world.
  2. There will be a drastic change in weather patterns bringing more floods or droughts in some areas.
  3. Biological diversity may get modified, some species ranges get redefined. Tropics and sub-tropics may face the problem of decreased food production.

Question 31. Mention any three sources of carbon dioxide emission.

  1. Coal based power plants, by the burning of fossil fuels for electricity generation.
  2. Combustion of fuels in the engines of automobiles, commercial vehicles and air planes contribute the most of global warming.
  3. Agricultural practices like stubble burning result in emission of CO2.

Question 32. What are the adverse effects of global warming on plants?

  1. Low agricultural productivity in tropics
  2. Frequent heat waves (Weeds, pests, fungi need warmer temperature)
  3. Increase of vectors and epidemics
  4. Strong storms and intense flood damage
  5. Water crisis and decreased irrigation
  6. Change in flowering seasons and pollinators
  7. Change in Species distributional ranges
  8. Species extinction

Question 33. Suggest few ways to overcome global warming.

  1. Increasing the vegetation cover, grow more trees
  2. Reducing the use of fossil fuels and green house gases
  3. Developing alternate renewable sources of energy
  4. Minimising uses of nitrogeneous fertilizers, and aerosols.

Question 34. Ozone acts a a natural sun screen – Justify.
Answer: Ozone depletion in the stratosphere results in more UV radiations especially UV B radiations (shortwaves). UV B radiation destroys biomolecules (skin ageing) and damages living tissues. UV – C is the most damaging type of UV radiation, but it is completely filtered by the atmosphere (ozone layer). UV – a contribute 95% of UV radiation which causes tanning burning of skin and enhancing skin cancer. Hence the uniform ozone layer is critical for the wellbeing of life on earth.

Question 35. Give a detailed account on clean development mechanism.
Answer: Clean Development Mechanism (CDM) is defined in the Kyoto protocol (2007) which provides project based mechanisms with two objectives to prevent dangerous climate change and to reduce green house gas emissions. CDM projects helps the countries to reduce or limit emission and stimulate sustainable development.

An example for CDM project activity, is replacement of conventional electrification projectswith solar panels or other energy efficient boilers. Such projects can earn Certified Emission I Reduction (CER) with credits / scores, each equivalent to one tonne of CO2, which can be counted towards meeting Kyoto targets.

Question 36. What are the major activities carried out by forestry extension centres?

  1. Training on tree growing methods
  2. Publicity and propaganda regarding tree growing
  3. Formation of demonstration plots
  4. Raising and supply of seedlings on subsidy
  5. Awareness creation among school children and youth about the importance of forests through training and camps.

Question 37. Prosopis juliflora, though an alien invasive species to India, it is beneficial to certain extent. Give reason.
Answer: Prosopis juliflora is used to arrest wind erosion and stabilize sand dunes on coastal and desert areas. It can absorb hazardous chemicals from soil and it is the main source of charcoal.

Question 38. Write a short note on Chipko Movement. Chipko Movement:
Answer: The tribal women of Himalayas protested against the exploitation of forests in 1972. Later on it transformed into Chipko Movement by Sundarlal Bahuguna in Mandal village of Chamoli district in 1974. People protested by hugging trees together which were felled by a sports goods company. Main features of Chipko movement were,

  1. This movement remained non political
  2. It was a voluntary movement based on Gandhian thought.
  3. It was concerned with the ecological balance of nature
  4. Main aim of Chipko movement was to give a slogan of five Fs – Food, Fodder, Fuel, Fibre and Fertilizer, to make the communities self sufficient in all their basic needs.

Question 39. Give a brief account on In-situ conservation.
Answer: In-situble conservation means conservation and management of genetic resources in their natural habitats. Here the plant or animal species are protected within the existing habitat. Forest trees, medicinal and aromatic plants under threat are conserved by this method. This is carried out by the community or by the State conservation which include wildlife, National park and Biosphere reserve. The ecologically unique and biodiversity rich regions are legally protected as wildlife sanctuaries, National parks and Biosphere reserves. Megamalai, Sathyamangalam wildlife, Guindy and Periyar National park, and Western ghats, Nilgiris, Agasthyamalai and Gulf of Mannar are the biosphere reserves of Tamil Nadu.

Question 40. What do you mean by Biochar? How it helps the environment?
Answer: Biochar is a long term method to store carbon. To increase plants ability to store more carbon, plants are partly burnt such as crop waste, waste woods to become carbon rich slow decomposing substances of material called Biochar. It is a kind of charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon and can endure in soil for thousands of years. Like most charcoal, biochar is made from biomass via pyrolysis. (Heating biomas in low oxygen environment) which arrests wood from complete burning.

Biochar thus has the potential to help mitigate climate change via carbon sequestration. Independently, biochar when added to soil can increase soil fertility of acidic soils, increase agricultural productivity, and provide protection against some foliar and soil borne diseases. It is a good method of preventing waste woods and logs getting decayed instead we can convert them into biochar thus converting them to carbon storage material.

Question 41. Explain the role of lakes in an ecosystem.
Answer: Lakes as a storage of rain water provides drinking water, improves ground water level and preserve the fresh water bio-diversity and habitat of the area where in occurs.

In terms of services lakes offer sustainable solutions to key issues of water management and climatic influences and benefits like nutrient retention, influencing local rainfall, removal of pollutants, phosphorous and nitrogen and carbon sequestration.

5 – Mark Questions

Question 42. List out the major effects of Ozone depletion.
Answer: The main ozone depletion effects are:

  1. Increases the incidence of cataract, throat and lung irritation and aggravation of asthma or emphysema, skin cancer and diminishing the functioning of immune system in human beings.
  2. Juvenile mortality of animals.
  3. Increased incidence of mutations.
  4. In plants, photosynthetic chemicals will be affected and therefore photosynthesis will be inhibited. Decreased photosynthesis will result in increased atmospheric CO2 resulting in global warming and also shortage of food leading for food crisis.
  5. Increase in temperature changes the climate and rainfall pattern which may result in flood / drought, sea water rise, imbalance in ecosystems affecting flora and fauna.

Question 43. What are the objectives of Afforestation programme?
Answer: Afforestation Objectives:

  1. To increase forest cover, planting more trees, increases CO2 production and air quality.
  2. Rehabilitation of degraded forests to increase carbon fixation and reducing CO2 from atmosphere.
  3. Raising bamboo plantations.
  4. Mixed plantations of minor forest produce and medicinal plants.
  5. Regeneration of indigenous herbs / shrubs.
  6. Awareness creation, monitoring and evaluation.
  7. To increase the level and availability of water table or ground water and also to reduce nitrogen leaching in soil and nitrogen contamination of drinking water, thus making it pure not polluted with nitrogen.
  8. Nature aided artificial regeneration.

Question 44. How Eichhornia crassiper spoils the Indian ecosystem?
Answer: Eichhornia crassipes is an invasive weed native to South America. It was introduced as aquatic ornamental plant, which grows faster throughout the year. Its widespread growth is a major cause of biodiversity loss worldwide. It affects the growth of phytoplanktons and finally changing the aquatic ecosystem.

It also decreases the oxygen content of the waterbodies which leads to eutrophication. It poses a threat to human health because it creates a breeding habitat for disease causing mosquitoes (particularly Anopheles) and snails with its free floating dense roots and semi submerged leaves. It also blocks sunlight entering deep and the waer ways hampering agriculture, fisheries, recreation and hydropower.

Question 45. Write a comparative note on Carbon Foot Print (CFP).
Answer: Every human activity leaves a mark just like our footprint. This Carbon foot print is the total amount of green house gases produced by human activities such as agriculture, industries, deforestation, waste disposal, buring fossil fuels directly or indirectly. It can be measured for an individual, family, organisation like industries, state level or national level. It is usually estimated and expressed in equivalent tons of CO2 per year.

The burning of fossil fuels releases CO2 and other green house gases. In turn these emissions trap solar energy and thus increase the global temperature resulting in ice melting, submerging of low lying areas and inbalance in nature like cyclones, tsunamis and extreme weather conditions. To reduce the carbon foot print we can follow some practices like

  1. Eating indigenous fruits and products
  2. Reduce use of your electronic devices
  3. Reduce travelling
  4. Do not buy fast and preserved, processed, packed foods
  5. Plant a garden
  6. Less consumption of meat and sea food. Poultry requires little space, nutrients and less pollution comparing cattle farming
  7. reduce use of Laptops (when used for 8 hours, it releases nearly 2 kg. of CO2 annually)
  8. Line dry your clothes. (Example: If you buy imported fruit like kiwi, indirectly it increases CFP. How? The fruit has travelled a long distance in shipping or airliner thus emitting tons of CO2)

Question 46. Write in detail about Remote sensing and its uses.
Answer: Remote Sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area. It is an tool used in conservation practices by giving exact picture and data on identification of even a single tree to large area of vegetation and wild life for classification of land use patterns and studies, identification of biodiversity rich or less areas for futuristic works on conservation and maintenance of various species including commercial crop, medicinal plants and threatened plants. Specific uses

  1. Helps predicting favourable climate, for the study of spreading of disease and controlling it.
  2. Mapping of forest fire and species distribution.
  3. Tracking the patterns of urban area development and the changes in Farmland or forests over several years.
  4. Mapping ocean bottom and its resources.

Higher Order Thinking Skills (HOTs) Questions

Question 1. Name the movement launched by the people of Mandal village to protect the trees by hugging them.
Answer: Chipko movement.

Question 2. Recently in January 2019, our Tamil Nadu Government had imposed a ban on using 14 different products of plastic origin. Mention any six plastic products that you know.

  1. Water Packets
  2. Plastic straws
  3. Plastic carry bags
  4. Thermocol cups
  5. Plastic coated paper plates
  6. Plastic flags.

Question 3. Due to plastic ban scheme in our state, people are gradually switching over to other optionals for daily activities. As a biology student, suggest few eco-friendly alternatives for this issue.

  1. Cloth / Jute bags
  2. Plantain leave, palmyra plates as plates
  3. Metal cups
  4. Earthen pots or ceramic wares
  5. Paper made flags

Question 4. Deforestation is creating various adverse effect on environment. Enlist the consequences of deforestation.

  1. Increased global warming.
  2. Loss of livelihood for forest dwellers.
  3. Loss of bio-diversity
  4. Decrease in soil fertility.
  5. Decline in annual rainfall.

How to Prepare using Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF?

Students must prepare for the upcoming exams from Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes PDF by following certain essential steps which are provided below.

  • Use Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues notes by paying attention to facts and ideas.
  • Pay attention to the important topics
  • Refer TN Board books as well as the books recommended.
  • Correctly follow the notes to reduce the number of questions being answered in the exam incorrectly
  • Highlight and explain the concepts in details.

Samacheer Kalvi 12th Bio Botany All Chapter Notes PDF Download

Frequently Asked Questions on Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes

How to use Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues Notes for preparation??

Read TN Board thoroughly, make separate notes for points you forget, formulae, reactions, diagrams. Highlight important points in the book itself and make use of the space provided in the margin to jot down other important points on the same topic from different sources.

How to make notes for Samacheer Kalvi 12th Bio Botany Chapter 8 Environmental Issues exam?

Read from hand-made notes prepared after understanding concepts, refrain from replicating from the textbook. Use highlighters for important points. Revise from these notes regularly and formulate your own tricks, shortcuts and mnemonics, mappings etc.


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