HomeLearn Fast select Course
Change UnitChange SubjectLast Menu
NEET-XII-Biology

14: Ecosystem

 
  • #
    14 - Ecosystem
  • #
    Section : I
    Page No 256:
  • #1-a
    Plants are called as_________ because they fix carbon dioxide.
    Ans : Plants are called as because they fix carbon dioxide.
  • #1-b
    In an ecosystem dominated by trees, the pyramid (of numbers) is _________ type.
    Ans : In an ecosystem dominated by trees, the pyramid (of numbers) is oftype.
  • #1-c
    In aquatic ecosystems, the limiting factor for the productivity is _________.
    Ans : In aquatic ecosystems, the limiting factor for productivity is.
  • #1-d
    Common detritivores in our ecosystem are_________.
    Ans : Common detritivores in our ecosystem are.
  • #1-e
    The major reservoir of carbon on earth is_________.
    Ans : A major reservoir of carbon on Earth is.

    SECTION I SECTION I Page No 257:
  • Qstn #2
    Which one of the following has the largest population in a food chain?

    -(a) Producers

    (b) Primary consumers

    (c) Secondary consumers

    (d) Decomposers
    Ans : (d) Decomposers

    Decomposers include micro-organisms such as bacteria and fungi. They form the largest population in a food chain and obtain nutrients by breaking down the remains of dead plants and animals.
  • Qstn #3
    The second trophic level in a lake is-

    -(a) Phytoplankton

    (b) Zooplankton

    (c) Benthos

    (d) Fishes
    Ans : (b) Zooplankton

    Zooplankton are primary consumers in aquatic food chains that feed upon phytoplankton. Therefore, they are present at the second trophic level in a lake.
  • Qstn #4
    Secondary producers are

    -(a) Herbivores

    (b) Producers

    (c) Carnivores

    (d) None of the above
    Ans : (d) None of the above

    Plants are the only producers. Thus, they are called primary producers. There are no other producers in a food chain.
  • Qstn #5
    What is the percentage of photosynthetically active radiation (PAR), in the incident solar radiation.

    -(a) 100%

    (b) 50 %

    (c) 1-5%

    (d) 2-10%
    Ans : (b) 50%

    Out of total incident solar radiation, about fifty percent of it forms photosynthetically active radiation or PAR.
  • Qstn #6
    Distinguish between (a) Grazing food chain and detritus food chain
    (b) Production and decomposition
    (c) Upright and inverted pyramid
    (d) Food chain and food web
    (e) Litter and detritus
    (f) Primary and secondary productivity
    Ans : (a) Grazing Food Chain (GFC) begins with primary producers or plants and ends in carnivores (tertiary or top carnivores) whereas Detritus Food Chain (DFC) begins with detritus or dead organic matter and it ends in carnivores. In GFC, energy for the food chain comes from sun whereas in DFC, energy for the food chain comes from organic remains or detritus.
    (b) Production is the phenomenon in which the energy is produced by the process of synthesis of organic compound from inorganic substances (such as ``\ce{C02}``, ``\ce{H20}`` & minerals) utilizing generally the sunlight. It traps energy.
    (c) In upright pyramid (e.g., grassland & cropland ecosystem), biomass or number of organisms or amount of energy decreases
    (d) A food chain is a sequence of different types of organisms by which the flow of energy occurs from one trophic level to another whereas food web is the network of various food chains inter-connected to each other. Food webs increase adaptability and competitiveness of the organisms.
    (e) Litter is the dead organic material fallen on the surface of the soil like leaves, remains of animals and excreta. Detritus is the dead organic matter found below the soil surface which is eaten up by the detritivores or broken down by decomposers.
    (f) Primary productivity is the rate of synthesis of biomass or energy fixation by the plants. It is comparatively quite high.
  • #6-a
    Grazing food chain and detritus food chain
    Ans : Grazing Food Chain (GFC) begins with primary producers or plants and ends in carnivores (tertiary or top carnivores) whereas Detritus Food Chain (DFC) begins with detritus or dead organic matter and it ends in carnivores. In GFC, energy for the food chain comes from sun whereas in DFC, energy for the food chain comes from organic remains or detritus.
  • #6-b
    Production and decomposition
    Ans : Production is the phenomenon in which the energy is produced by the process of synthesis of organic compound from inorganic substances (such as ``\ce{C02}``, ``\ce{H20}`` & minerals) utilizing generally the sunlight. It traps energy.
next page