everyday science MCQ #3772

For a healthy aquatic ecosystem, dissolved oxygen (DO) in water should be at least ______.

everyday science MCQ #3772

  1. Question 1

    Q1. For a healthy aquatic ecosystem, dissolved oxygen (DO) in water should be at least ______.

    • A) 0.4 to 0.5 ppm
    • B) 4 to 5 ppm
    • C) 4000 to 8000 ppm
    • D) 400 to 800 ppm

    Answer: 4 to 5 ppm

    Explanation: Aquatic organisms require a dissolved oxygen level of at least 4–5 ppm for survival; below this threshold, most fish and aerobic organisms cannot respire adequately.