SSC Ecology And Environment Sample Paper NCERT Sample Paper-1

  • question_answer
    Algal blooms in a lake

    A) Leads to oxygen depletion

    B) Increase \[C{{O}_{2}}\] level

    C) Kills fishes and other organisms

    D) all of the above.

    Correct Answer: D

    Solution :

    An algal bloom is a rapid increase or accumulation in the population of algae (typically microscopic) in a water system. Algal blooms are the result of an excess of nutrients, particularly some phosphates. The excess of nutrients may originate from fertilizers that are applied to land for agricultural or recreational purposes. When phosphates are introduced into water systems, higher concentrations cause increased growth of algae and plants. Algae tend to grow very quickly under high nutrient availability, but each alga is short-lived, and the result is a high concentration of dead organic matter which starts to decay. The decay process consumes dissolved oxygen in the water, resulting in hypoxic conditions. Without sufficient dissolved oxygen in the water, animals and plants may die off in large numbers.


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