With reference to the planet Earth, consider the following statements:
I. Rain forests 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?
- A.I and II
- B.II only
- C.I and III
- D.None of the above statements is correct
▶ Answer & Explanation
Correct answer: B. II only
Marine phytoplankton, along with photosynthetic bacteria, are collectively responsible for a substantial portion, often cited as around 50%, of the Earth's atmospheric oxygen through photosynthesis. While rainforests are vital for oxygen production and carbon sequestration, the vastness of the oceans and the sheer biomass of phytoplankton make them a primary source of global oxygen. Furthermore, atmospheric air has a higher concentration of oxygen (approximately 21%) compared to dissolved oxygen in surface waters, which varies but is generally significantly lower.
Source: UPSC gs1 2025