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IAS Exam: Prelims Environment and Ecology Questions: Origin of earth and environment

Jan 28, 2016 17:48 IST

    Environment and Ecology has become indispensable for IAS Prelims Exam. Candidates cannot dispense with this section. In future also Importance of Environment and Ecology cannot be underestimated. Following are some MCQs that would help candidates to understand the kinds of questions they are going to face from Environment and Ecology section in IAS Prelims Exam:

    Q1. Consider the following statements
    1. Only 20% if earth’s fresh water is available in liquid form.
    2. Primary source of water on land is ground water.

    Select the correct answer from the following codes
    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: a

    Explanation: primary source of earth’s fresh water is rainfall. In land percentage of water stored is highest in ground water.

    Q2. Which of the following statement is incorrect with regard to the Atmosphere?
    a. On the basis of composition of gases atmosphere is divided into Heterosphere and Homosphere.
    b. The heterosphere begins around 80 km altitude and extends outward some 10000 km.
    c. Above 480 km, the atmosphere is nearly a vacuum, called exosphere which contains individual atoms of the gases like hydrogen and helium.
    d. The uppermost layer of the atmosphere called stratosphere

    Answer: d

    Explanation: The lower layer of the earth surrounding the Earth composed of the gases like nitrogen (78%), oxygen (21), argon (0.934%) carbon dioxide (0.03%) and other rare gases. The uppermost layer of the atmosphere called troposphere while stratosphere is just above the troposphere.

    Q3. Consider the following statements
    1. Environment includes both living and nonliving components.
    2. Environment includes pollutants and other factors that adversely affect our life.
    3. Environment is sum total of all forces, materials and influences around us at a given point of time and place.

    Select the correct answer from the following codes
    a. Only 3
    b. Only 1 and 3
    c. Only 2 and 3
    d. 1,2 and 3

    Answer: d

    Explanation:  Environment is the surroundings or conditions in which an organism lives or operates. All the above statements refer to environment.

    Q4. Landforms of earth surface includes
    1. Rocks
    2. Swamps
    3. Mountains
    4. Grasslands
    5. Ponds
    6. Lakes

    Select the correct answer from the following codes
    a. Only 1 and 4
    b. Only 1 , 4 and 5
    c. 1,2,3,4 and 6
    d. 1,2 ,3 and 4

    Answer: d

    Explanation: Land forms just approximately 29% of the earth’s surface which includes mountains, rocks, deserts, swamps, forests and grasslands. Rivers, ponds, lakes, waterfalls are surface water bodies.

    Q5. Which of the following are gases of primitive atmosphere?
    1. Methane
    2. Nitrogen
    3. Oxygen
    4. CO2
    5. Hydrogen

    Select the correct answer from the following codes
    a. Only 3,4 and 5
    b. Only 2,3 and 4
    c. Only 1,4and 5
    d. 1,2 ,3,4 and 5

    Answer: c

    Explanation:  gases of primitive atmosphere were primarily methane, ammonia, CO2 and hydrogen. There was no free oxygen only water vapour filled the atmosphere.

    Q6. Consider the following statements
    1. Amoeba was the first living organism on the earth.
    2. Free oxygen in atmosphere was first released by chlorophyll containing bacteria.
    Select the correct answer from the following codes
    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: b

    Explanation:  Bacteria were the first living organism on the earth. Continued photosynthesis by chlorophyll containing bacteria progressively accumulated oxygen in the atmosphere. Thus atmosphere gradually transformed from reducing to oxidising.

    Q7. Consider the following statement about ozonosphere.
    1. Ozone is a highly reactive oxygen molecule made of three oxygen atoms (O3) present in ozonosphere.
    2. The ozonosphere is also known as the upper functional layer.
    3. Ozone absorbs wavelength of ultraviolet light and subsequently eradicates that energy at longer wavelengths, infrared energy.

    Which of the following statements is/are correct?
    a. Only 1
    b. Only 1 and 2
    c. Only 1 and 3
    d. All of the above

    Answer: c

    Explanation: The ozonosphere is also known as the lower functional layer. Usually the oxygen molecules having only two oxygen atoms (O2) but in the ozonosphere it contains three oxygen atoms (O3). In the ozonosphere, the process of filtration of harmful ultraviolet radiation from the incoming solar radiation has been done here. It works as safeguarding life at earth’s surface and heating the stratosphere.

    Q8. Consider the following statements regarding thermosphere.
    1. In thermosphere temperatures increase with height.
    2. High temperatures are generated in the thermosphere because the gas molecules absorb shortwave solar radiation.
    3. Despite such high temperatures, the thermosphere is not ‘hot’ as expected.

    Which of the following statement is/are correct?
    a. Only 1
    b. Only 1 and 2
    c. Only 1 and 3
    d. All of the above

    Answer: d

    Explanation: Thermosphere is directly above the mesosphere and below the exosphere. Thermosphere extends from 80 to 480 km in altitude where temperature rises sharply in the atmosphere, up to 1200 degree and higher. The transitional area between the thermosphere and mesosphere is referred to as the mesopause.

    Q9. Which of the following statements is incorrect about biosphere?
    a. Biosphere intricate, interconnected web that links all organism with their physical environment.
    b. The biosphere extends from the bottom of ocean trenches to about 1000 km above the sea level.
    c. The biosphere has evolved, reorganised itself at times, faced extinction, gained new vitality, and managed to flourish overall.
    d. Earth’s biosphere is the only one known in the solar system; thus, life as we know is unique to the earth.

    Answer: b

    Explanation: The biosphere is the zone, incorporating elements of the hydrosphere, lithosphere and atmosphere. Biosphere is also known as the ecosphere. The biosphere extends from the bottom of ocean trenches to about 8 km above the sea level.

    Q10. Consider the following statements regarding the features of the environment:
    1. At any given point of time, environment is the sum of biotic and abiotic components.
    2. Environment changes in space and time
    3. Environment generates its own organic matter which differs in space, from origin to region and climate to climate.

    Which of the following statement(s) is/are correct?
    a. Only 1
    b. Only 1 and 2
    c. Only 1 and 3
    d. All of the above

    Answer: d

    Explanation: Environment has been defined as ‘the sum total of all conditions and influences that affect the development of organisms’. Environment also tends to maintain an ecological balance on the earth. The working of environment and its dependent systems are governed by the flow of energy.

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

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