Q20.
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 photo-synthetic 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?
Answer
B
Explanation
estimate that roughly half of the oxygen on Earth comes from the ocean. The of this production is from oceanic plankton — plants, algae, and some bacteria that can One particular species, is the smallest photosynthetic on Earth. But this little bacteria produces up 20% of the oxygen in our entire biosphere. That’s a percentage than all of the tropical rainforests on combined. Hence, statement I is not correct. than half of the oxygen we breathe comes from photosynthesizers, like phytoplankton and Both use carbon dioxide, water and energy the sun to make food for themselves, releasing in the process. Hence, statement II is correct. content is highest at the surface. As depth dissolved oxygen declines, reaching a between a few hundred meters and 1000 m the aptly-named oxygen minimum layer. It should noted that even though dissolved oxygen is highest the surface, there is still far less oxygen in the water is found in the air. Well-oxygenated surface water only contain around 8 mg O2/l, while the air 210 mg O2/l. Hence, statement III is not