“If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys.” Which one of the following functions of wetlands best reflects the above statement ?
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Answer: D. Kidneys filter waste from the blood. Wetlands do the same for water: aquatic plants absorb heavy metals and excess nutrients, cleaning the water that passes through. That filtering role is what the 'kidneys' comparison means.
Watch for: Option C on sedimentation also sounds like cleaning, but the kidney idea is about removing pollutants.
Why the other options are wrong
- A. Wrong because the water cycle describes movement of water, not filtering.
- B. Wrong because a food base describes productivity, not filtering.
- C. Wrong because sediment balance and soil stability are not the 'cleaning' role of kidneys.
Source to check: Ramsar Convention Secretariat, 'Wetlands: a global disappearing act' and Wetland Ecosystem Services factsheets; NCERT Class 12 Biology, Chapter 14 (Ecosystem)
Answer from the official UPSC key. Written and fact-checked by AI against the official key. Spotted a mistake? Report it.