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12 questions · timed · auto-graded

Question 13 Marks
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.
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Question 23 Marks
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.
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Question 33 Marks
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.
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Question 43 Marks
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.
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Question 53 Marks
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.
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Question 63 Marks
What are the major activities carried out by forestry extension centres?
Answer
  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.
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Question 73 Marks
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 $CO _2$, which can be counted towards meeting Kyoto targets.
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Question 83 Marks
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.
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Question 93 Marks
Suggest few ways to overcome global warming.
Answer
  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.
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Question 103 Marks
What are the adverse effects of global warming on plants?
Answer
  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
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Question 113 Marks
Mention any three sources of carbon dioxide emission.
Answer
  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 $CO _2$.
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Question 123 Marks
List out the effects of global warming.
Answer
  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.
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[ 3 Marks Questions ] - BIO BOTANY STD 12 Questions - Vidyadip