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 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?
Show answer
Answer: B. Statement I is wrong: oceans produce about half of Earth's oxygen, more than rainforests. Statement II is correct: marine phytoplankton and photosynthetic bacteria such as Prochlorococcus produce about 50% of the world's oxygen. Statement III is wrong: air is about 21% oxygen, while even well-oxygenated surface water holds only a small fraction of that. So only II is correct.
Watch for: Rainforests are called the 'lungs of the Earth', but the ocean produces more oxygen.
Why the other options are wrong
- A. Wrong: Statement I is false because oceans produce more oxygen than rainforests.
- C. Wrong: Statements I and III are both false.
- D. Wrong: Statement II is correct.
Source to check: NOAA National Ocean Service, 'How much oxygen comes from the ocean?' (oceanservice.noaa.gov).
Answer from the official UPSC key. Written and fact-checked by AI against the official key. Spotted a mistake? Report it.