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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.
#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.
#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.
#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.
#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? ?Ans-c
- 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.