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4th Class Science Our Environment Question Bank Our Environment

  • question_answer
    A factory was set up in an area which used to discharge its untreated waste down the pipe into nearby water body. After few years the factory was shut down due to some legal action. The given graph shows the changes in the populations of two organisms X and Y over time, before the setting of factory and after it was shut down. Identify X and Y and select the correct option.

    A)  X could be bacteria and Y could be fish.

    B)  X could be prawn and Y and could be a submerged aquatic plant.

    C)  X could be a water bird and Y could be algae.

    D)  X could be algae and Y could be bacteria.

    Correct Answer: A

    Solution :

    The given graph shows that the population of X increases after the setup of factory and simultaneously decreases after the factory is shut down. Opposite of this occurs in case of Y. Factory discharges many harmful chemicals in the water which pollute it. Many harmful microorganisms like bacteria grow in the polluted water and such water harm aquatic life and kill fishes and other aquatic animals and plants. Hence, X could be bacteria and Y could be fish.


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