Environment -01


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#1 With reference to composting, consider the following statements: 1. It is a method of decomposition of solid wastes. 
 2. It requires high moisture content for the biological breakdown of the waste. 
 3. Carbon dioxide and heat are the by- products in the composting process. Which of the statements given above is/are correct??Ans-a

  • Composting is the natural process of ‘rotting’ or decomposition of organic matter by microorganisms under controlled conditions.
  • Raw organic materials such as crop residues, animal wastes, food garbage, some municipal wastes and suitable industrial wastes, enhance their suitability for application to the soil as a fertilizing resource, after having undergone composting.
  • Moisture content is an important factor in aerobic composting.
  • The moisture content if about 55 percent is beneficial for biological breakdown of the


  • It may be sometimes necessary to add water in to maintain moisture content.
  • The microorganisms such as fungi and bacteria help to stabilise the organic matter.
  • Compost produced acts as a good fertilizer for plants.
  • The composting process also produces carbon dioxide and heat which can be used for

    various purposes like cooking.

  • Composting may be divided into two categories by the nature of the decomposition process.
  • In anaerobic composting, decomposition occurs where oxygen is absent or in limited supply.
  • Under this method, anaerobic micro-organisms dominate and develop intermediate compounds including methane, organic acids, hydrogen sulphide and other substances.
  • In the absence of O, these compounds accumulate and are not metabolized further. Many of these compounds have strong odours and some present phytotoxicity.
  • As anaerobic composting is a low-temperature process, it leaves weed seeds and pathogens intact.
  • Moreover, the process usually takes longer than aerobic composting.
  • Aerobic composting takes place in the presence of ample O.
  • In this process, aerobic microorganisms break down organic matter and produce carbon dioxide (CO2), ammonia, water, heat and humus, the relatively stable organic end product.
  • Although aerobic composting may produce intermediate compounds such as organic acids, aerobic micro- organisms decompose them further.
  • The resultant compost, with its relatively unstable form of organic matter, has little risk of phytotoxicity.
  • The heat generated accelerates the breakdown of proteins, fats and complex carbohydrates such as cellulose and hemi-cellulose. Hence, the processing time is shorter.
  • Although more nutrients are lost from the materials by aerobic composting, it is considered more efficient and useful than anaerobic composting for agricultural production.
  • Most of this publication focuses on aerobic composting.
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#2 Which of the following statements is/are correct about a wildlife sanctuary? 1. A wildlife sanctuary is generally species oriented. 
 2. Human activity is completely prohibited in a wildlife sanctuary. 
 Select the correct answer using the code given below.
?Ans- a

-wild animal and plant species are protected.
-Human activities like tilling of land, collection of minor forest produce, harvesting of timber and private ownership rights are allowed in wild life sanctuary.

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#3 Which of the following statements regarding biogas is not correct??Ans- b

Biogas refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. It is a type of biofuel. It is produced by anaerobic fermentation of bio-degradable materials such as biomass, manure or sewage, municipal waste, green waste and energy crops.

Importance of biogas:

  • When cow dung is put in a biogas plant, two main products are obtained- (a) methane gas which can be used as a fuel for domestic purposes and (b) liquid humus that can be used as a natural fertilizer.
  • Biogas can be generated from locally available materials like animal dung, vegetable wastes, agricultural wastes, etc. In this way, waste is a managed and converted into useful products.
  • Biogas is a clean fuel as it burns without smoke or any odour and is ashless.
  • Biogas has a high calorific value. It has been estimated that a small family of four persons required 4.25% of biogas per day.
  • Biogas provides about 5 times more energy than the direct burning of the same quantity of dried dung cakes.
  • The fertilizer left after extracting biogas has 43% more strength than dung used directly as manure.
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#4 Consider the following statements regarding humus: 1. It is highly prone to microbial action. 
 2. It serves as a reservoir of nutrients in nature. 
 3. It undergoes decomposition at very fast rate. 
 Which of the statements given above is/are correct??Ans-a

  • Humification leads to accumulation of a dark coloured amorphous substance called humus.
  • It is the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.
  • Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
  • Humus significantly influences the density of soil and contributes to moisture and nutrient retention.
  • Being colloidal in nature it serves as a reservoir of nutrients.
  • It contains many useful nutrients for healthy soil, nitrogen being the most important of all.
  • Soil formation begins with the weathering of humus.
  • The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.
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#5 Consider the following statements: 1. Boundaries of national parks are marked by legislation. 
 2. Cultivation and grazing activities are not allowed inside a national park. 
 Which of the statements given above is/are correct?

  • Whenever it appears to the State Government that an area by reason of its ecological, faunal, floral, geomorphological, or zoological association or importance, needs to be constituted as a National Park.
  • Alteration of the boundaries of a National Park can be made only through a resolution passed by the Legislature of the State.
  • Unlike a Sanctuary, where certain rights can be allowed, in a National Park, no rights are allowed. No grazing of any livestock shall also be permitted inside a National Park while in a Sanctuary, the Chief Wildlife Warden may regulate, control or prohibit it.
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