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IAS Prelims Exam: Environment and Ecology NIOS Questions: Conservation of Soil and Land

Jul 14, 2016 14:56 IST

    In UPSC IAS Prelims Exam, the subject Environment and Ecology considered as the one of the most important sections among all the subjects of UPSC IAS Exam syllabus. The UPSC IAS aspirants required to prepare this subject very well because of growing importance of this subject at global level. So, here we have created Multiple Choice Questions of Environment and Ecology based on the NIOS Study Material for UPSC IAS Prelims Exam Preparation.


    1.    Consider the following statements regarding the land and soil resources:
    I.    Rapid increase in human population has placed a great strain on the land and soil resources resulting in land degradation and soil erosion.
    II.    Soil is the uppermost layer of the earth’s crust, which can be dug or ploughed, and in which plants grow.
    III.    Land is a solid, substratum which supports human and many other organisms.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:

    Rapid increase in human population has placed a great strain on the land and soil resources resulting in land degradation and soil erosion. Soil is the uppermost layer of the earth’s crust, which can be dug or ploughed, and in which plants grow. Land is a solid, substratum which supports human and many other organisms. On a worldwide basis more than 4.85 billion acres (1.96 billion hectares) or 17% of the earth under vegetation has been degraded by humans to various extents.

    2.    Consider the following statements regarding the soil and land conservation:
    I.    Soil erosion is the loosening and displacement of topsoil particles from the land.
    II.    Soil erosion is a natural process that occurs on all lands.
    III.    Land degradation is the deterioration in the quality of land.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:


    Soil erosion is the loosening and displacement of topsoil particles from the land. Soil erosion is a natural process that occurs on all lands. Soil erosion may occur at a slow or fast rate.

    Land degradation is the deterioration in the quality of land. Degradation of land results in loss of crop production capacity of the land.

    Environment and Ecology NIOS Questions: Conservation of other Natural resources

    3.    Consider the following statements regarding the pace of soil erosion:
    I.    Geological erosion (Geo: earth) is a slow process that continues relatively unnoticed and has been occurring for millions of years.
    II.    The first phase of this soil forming process is called weathering which is a physico- chemical process that leads to the breakdown of rocks by wind and water into small fragments and formation of soil particles.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    Only II
    c.    Both I and II
    d.    Neither I nor II

    Answer: c

    Explanation:

    Geological erosion (Geo: earth) is a slow process that continues relatively unnoticed and has been occurring for millions of years. The first phase of this soil forming process is called weathering which is a physico- chemical process that leads to the breakdown of rocks by wind and water into small fragments and formation of soil particles.

    4.    Consider the following statements regarding accelerated erosion of soil:
    I.    Accelerated soil erosion occurs when the protective vegetation cover is destroyed.
    II.    Accelerated soil erosion may occur due to natural causes like flooding or due to human activities.
    III.    The rate and extent of accelerated soil erosion is much higher as compared to natural geological soil erosion.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:

    Accelerated soil erosion occurs when the protective vegetation cover is destroyed. This may occur due to natural causes like flooding or due to human activities. One of the main human activities responsible for accelerated soil erosion is cultivation of land.

    Land under cultivation is more vulnerable to natural agencies like wind and water. Human activities accelerate removal of surface soil by wind and /or water at a faster rate. The rate and extent of accelerated soil erosion is much higher as compared to natural geological soil erosion.

    5.    Consider the following statements regarding the types of soil erosion:
    I.    Soil erosion by water occurs by means of raindrops, waves or ice.
    II.    Soil erosion by water is termed differently according to the intensity and nature of erosion.
    III.    Soil erosion by wind is more common in areas where the natural vegetation has been destroyed.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:

    Soil erosion is classified on the basis of the physical agent responsible for erosion. The various types of soil erosion are consequently referred to as: (a) Water erosion (b) Wind erosion.

    Running water is one of the main agents, which carries away soil particles. Soil erosion by water occurs by means of raindrops, waves or ice. Soil erosion by water is termed differently according to the intensity and nature of erosion.

    Soil erosion by wind is more common in areas where the natural vegetation has been destroyed. Such conditions occur mainly in arid and dry areas along the sandy shores of oceans, lakes and rivers.

    6.    Consider the following statements regarding the raindrop erosion of soil:
    I.    Raindrops falling on land surface cause detachment of the soil particles and the loose soil particles are washed away by flowing water.
    II.    An average size of raindrop is approximately 5 mm in diameter falling through the air hits the soil at a velocity of 32 km/hr. larger raindrops and gusts of wind hit the soil surface even at higher velocities.
    III.    Raindrops behave like tiny bombs when falling on exposed soil, displace soil particles and destroy soil structure.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:


    Raindrops falling on land surface cause detachment of the soil particles. The loose soil particles are washed away by flowing water. Raindrops thus initiate water erosion. An average size of raindrop is approximately 5 mm in diameter falling through the air hits the soil at a velocity of 32 km/hr. larger raindrops and gusts of wind hit the soil surface even at higher velocities.

    Raindrops behave like tiny bombs when falling on exposed soil, displace soil particles and destroy soil structure. Presence of vegetation on land prevents raindrops from falling directly on the soil thus erosion of soil in areas covered by vegetation is prevented. With continued rainfall the displaced soil particles fill in the spaces between soil particles and so prevent water from seeping into the soil.

    After a while this result in accumulation of water called ‘ponding’ on the land.  This water begins to flow. This flowing water is called runoff and is muddy due to the displaced soil particles in it. As the water moves in further erodes the soil surface.

    7.    Consider the following statements regarding the consequences of soil erosion:
    I.    The fine particles of the topsoil which contain the bulk of nutrients and organic matter needed by the plants are lost from soil erosion.
    II.    Erosion may result in removal of seeds or seedlings so that the soil becomes bare and the bare soil is more vulnerable to erosion both by wind and water.
    III.    Sheet, rill, gully and stream bank erosion also cause siltation of rivers, streams and fields and the deposition of silt results in damage of crops and pastures, and sedimentation of water bodies like streams, dams, reservoirs etc.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:


    Following are the consequences of soil erosion:
    1. The fine particles of the topsoil which contain the bulk of nutrients and organic matter needed by the plants are lost from soil erosion. Erosion removes the most fertile part of soil. The less fertile subsoil is left.
    2. Erosion may result in removal of seeds or seedlings so that the soil becomes bare. Bare soil is more vulnerable to erosion both by wind and water.
    3. Removal of seeds and seedlings reduces the ability of soil to store water.
    4. Sheet, rill, gully and stream bank erosion also cause siltation of rivers, streams and fields. Deposition of silt results in damage of crops and pastures, and sedimentation of water bodies like streams, dams, reservoirs etc.
    5. Sedimentation of water bodies deteriorate water quality and damage aquatic habitats and organisms.
    6. Gully erosion also results in loss of large volumes of soil.
    7. Wider deep gullies sometimes reach 30 m and thus severely limit land use.
    8. Stream bank erosion not only causes loss of land, but also changes the course of a river or stream.
    9. Stream banks erosion also damage public roads.
    10. Mass movement of land or landslides also inhibits farm production and land use.
    11. It also causes mortality in animals and humans.
    12. Coastal erosion causes the adjourning land to become covered by sand.

    8.    Consider the following statements regarding the prevention of soil erosion:
    I.    The vegetation cover is important because roots of plants hold soil particles together.
    II.    Crop rotation and keeping the land fallow (not planting anything in the soil for sometime) should be adopted.
    III.    Vegetation and soil management should be improved in order to increase soil organic matter.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:

    Soil erosion can be prevented through following measures:
    1. It is essential to retain vegetation cover that soil is not exposed to rain. The vegetation cover is important because roots of plants hold soil particles together. Plants intercept rainfall and protect soil from direct impact of raindrops.
    2. Cattle grazing should be controlled.
    3. Crop rotation and keeping the land fallow (not planting anything in the soil for sometime) should be adopted.
    4. Vegetation and soil management should be improved in order to increase soil organic matter.
    5. To prevent stream bank erosion runoff water should be stored in the catchment for as possible by maintaining vegetation cover and as by constructing dams for storing water.
    6. For prevention or reduction of coastal erosion, protective vegetation along the beaches should be re-established. The best method of controlling coastal dune erosion is not to disturb the dunes and the coastal system. Further, construction of buildings and other development should be located behind the dune system.


    9.    Consider the following statements regarding the consequences of soil erosion by wind:
    Wind erosion removes the finer soil material including organic matter, clay and slit, in a suspension (colloidal) form and leaving behind coarser, less fertile material.
    Productive capacity of the soil is lost as most of the plant nutrients which remain attached smaller colloidal soil fraction are lost.
    Wind erosion also damages roads and fertile agricultural fields by depositing large quantities of air blown soil particles.

    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:

    Soil erosion by wind is more common in areas where the natural vegetation has been destroyed. Such conditions occur mainly in arid and dry areas along the sandy shores of oceans, lakes and rivers.

    Wind erosion removes the finer soil material including organic matter, clay and slit, in a suspension (colloidal) form and leaving behind coarser, less fertile material. Productive capacity of the soil is lost as most of the plant nutrients which remain attached smaller colloidal soil fraction are lost. Wind erosion also damages roads and fertile agricultural fields by depositing large quantities of air blown soil particles.

    10.    Consider the following statements regarding the remedial strategies for prevention of soil erosion by wind:

    I. Access of wind to the soil should be controlled by leaving the stubble or mulch on the soil.
    II. Wind speed can be broken or controlled by planting trees in form of a shelter belt.
    III. The practice of leaving the land fallow (i.e. not planting anything in the field) and use of machinery should be modified.


    Which of the following statement(s) is/are correct?
    a.    Only I
    b.    I and II
    c.    II and III
    d.    All of the above

    Answer: d

    Explanation:


    Following are the remedial measures for prevention of soil erosion by wind:
    1. The vegetation cover over sandy soils should be kept above 30%.  Access of wind to the soil should be controlled by leaving the stubble or mulch on the soil. (Stubble is the remains of crop left after harvesting).
    2. Wind speed can be broken or controlled by planting trees in form of a shelter belt.
    3. The practice of leaving the land fallow (i.e. not planting anything in the field) and use of machinery should be modified. This can be done by using direct- drilling techniques (ploughing the field) and by using direct-drilling techniques.
    4. Over grazing by cattle should be avoided.

    The study of conservation of Natural resources is very important for UPSC IAS aspirants because of its scarcity in nature. Every citizen and the civil servants of the country must have knowledge regarding to manage the scarce resources.   The natural resources help to keep the biodiversity intact and the biodiversity helps to maintain balance in the ecosystem. In the last few years, the importance of the subject Environment and Ecology in UPSC IAS Exam has increased due to its growing concern at the global level. So, the UPSC IAS aspirants have to put equal effort on Environment and Ecology section like other sections of General Studies during their Preparation of UPSC IAS Exam.

    Click here for IAS Prelims: GS Environment and Ecology: Study Material

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