MDCAT Biology MCQ #403

During an experiment using the heavy isotope Oxygen-18, a scientist observes that the oxygen gas released by algae is radioactive. Which reactant provided this oxygen?

MDCAT Biology MCQ #403

  1. Question 1

    Q1. During an experiment using the heavy isotope Oxygen-18, a scientist observes that the oxygen gas released by algae is radioactive. Which reactant provided this oxygen?

    • A) Carbon dioxide
    • B) Water
    • C) Glucose
    • D) Chlorophyll

    Answer: Water

    Explanation: Oxygen released during photosynthesis originates from water through photolysis. Carbon dioxide is the tempting wrong choice, but it forms glucose.