Q. With reference to the planet Earth, consider the following statements:
I. Rainforests produce more oxygen than that produced by oceans.
II. Marine phytoplankton and photosynthetic bacteria produce about 50% of the world’s oxygen.
III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.
Which of the statements given above is/are correct?
✅ Correct Answer: (b) II only
Explanation:
Statement I – Incorrect: Oceans, especially through phytoplankton, produce significantly more oxygen than rainforests. Oceans contribute about 50–80% of Earth’s oxygen, whereas rainforests contribute around 28%.
Statement II – Correct: Marine phytoplankton and some photosynthetic bacteria together produce about half (or more) of the oxygen in our atmosphere.
Statement III – Incorrect: Oxygen concentration in air (~21% by volume) is much higher than in well-oxygenated surface waters (~8–10 mg/L).
