With reference to the planet Earth, consider the following statements:

Question

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?

1. A. I and II
2. B. II only (Correct answer)
3. C. I and III
4. D. None of the above statements is correct

Correct Answer

Option B — II only

Detailed Solution & Explanation

The correct answer is II only.

Key Points

• Rain forests and oceans both produce oxygen, but marine phytoplankton and photosynthetic bacteria generate approximately 50% of Earth's oxygen — more than rainforests, so Statement I is incorrect. Statement II is correct.
• Dissolved oxygen in well-oxygenated water is typically 8–12 mg/L (~8 ppm), while atmospheric air contains about 210,000 ppm oxygen — water contains far LESS oxygen than atmospheric air, making Statement III incorrect.