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IAS Exam: Prelims Environment and Ecology Questions: Ecosystem Set II

Jan 29, 2016 16:25 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. The amount of energy decreases at each subsequent tropic level. What are the reasons behind this?

    1. Energy is lost in respiration

    2. Part of energy is lost as heat

    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: c

    Explanation: At each tropic level a part of available energy is lost in respiration or used up in metabolism. A part of energy is lost at each transformation i.e. when it moves from lower to higher tropic level as heat.

    Q2. which type of pyramid gives true picture of tropic structure of an ecosystem?

    1. Pyramid of numbers
    2. Pyramid of biomass
    3. Pyramid of energy

    Select the correct answer from the following codes

    a. Only 3
    b. Only 1 and 2
    c. Only 2 and 3
    d. 1,2 and 3

    Answer: a

    Explanation: pyramid of energy is always upright in all ecosystem, it represents amount of energy in all tropic level.

    Q3. The food chains in ecosystem help in understanding which of the following?

    1. Feeding relations among organisms
    2. Flow of energy
    3. Concept of biomagnifications

    Select the correct answer from the following codes

    a. Only 1
    b. Only 1 and 2
    c. Only 2 and 3
    d. 1,2 and 3

    Answer: d

    Explanation: The study of food chains helps in understanding the feeding relations and interactions among different organisms in ecosystem. It explains flow of energy and circulation of materials in ecosystem. It helps in understanding the concept of biomagnifications in ecosystem.

    Q4. Consider the following statements

    1. In ecosystem flow of energy is linear, but that of nutrients is cyclical.

    2. The biosphere is a closed system.

    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: c

    Explanation: Flow of energy is linear because, it is used or lost as heat, as it flows forward. Flow of nutrients is cyclical because nutrients released by detritivore into soil are absorbed back from soil by root of green plants.

    Q5. Which of the following forms the reservoir pool of biogeochemical cycle?

    1. Atmosphere/rock
    2. Plants
    3. Animals

    Select the correct answer from the following codes

    a. Only 1
    b. Only 1 and 2
    c. Only 2 and 3
    d. 1,2 and 3

    Answer: a

    Explanation: Atmosphere/rocks form the reservoir pool of biogeochemical cycle because it stores large amount of nutrients. Plants and animals are compartments of cycle because they are short storages of carbon.

    Q6. In photosynthesis green plants?

    1. Releases carbon dioxide
    2. Releases oxygen
    3. Converts inorganic matter into organic matter
    4. Converts organic matter into inorganic matter

    Select the correct answer from the following codes

    a. Only 1 and 3
    b. Only 2 and 3
    c. Only 2 and 4
    d. Only 1 and 4

    Answer: b

    Explanation: Green plants in the presence of sunlight utilize carbon dioxide in the process of photosynthesis and convert inorganic carbon into organic matter and release oxygen.

    Q7. Consider the following statements

    1. In respiration plants utilize carbon dioxide and liberate energy
    2. In photosynthesis plants utilize oxygen and convert inorganic matter into organic matter.

    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: d

    Explanation: In respiration all living organisms release energy, carbon dioxide and water. In photosynthesis plants utilize water, carbon dioxide and convert inorganic matter into organic matter.

    Q8. which of the following supports Forest as reservoir of carbon dioxide?

    a. long life cycles of trees
    b. Oxygen released during photosynthesis
    c. Less carbon dioxide released during respiration
    d. None

    Answer: c

    Explanation: Forests act as reservoir of carbon dioxide, as carbon fixed by trees remains stored in them for long due to their long life cycles.

    Q9. Which of the following are also called as detritus feeders?

    a. Hetrotrophs
    b. Saprotrophs
    c. Autotrophs
    d. None

    Answer: b

    Explanation: decomposers also called saprotrophs decompose dead organic matter of plants and animals by secreting enzymes outside their body on decaying matter. They are called detritivore or detritus feeders.

    Q10. Which of the following statement is incorrect?

    a. High solar energy striking near the equator ensures nearly constant high temperatures and high rates of evaporation and plant transpiration.

    b. Energy is continually input into an ecosystem in the form of heat energy, and some energy is lost with each transfer to a lower tropic level.

    c. Nutrients are recycled within an ecosystem, and their supply normally limits biological activity.  So, "energy flows, elements cycle".

    d. Energy is moved through an ecosystem via a food web, which is made up of interlocking food chains.

    Answer:b

    Explanation: High solar energy striking near the equator ensures nearly constant high temperatures and high rates of evaporation and plant transpiration. Energy is continually input into an ecosystem in the form of light energy, and some energy is lost with each transfer to a higher tropic level.

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

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