"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?
Answer & explanation
Answer: (d) Aquatic plants absorb heavy metals and excess nutrients.
The kidney comparison is about purification: kidneys filter waste out of blood, and wetlands filter pollutants out of water. Option (d), aquatic plants absorbing heavy metals and excess nutrients, is the function that does this cleaning job.
- ✓ (d) Wetlands are called the earth's kidneys because they filter pollutants. Wetland plants take up heavy metals, and plant roots and microbes absorb excess nutrients from fertilizer, manure and sewage.
- ✗ (a) Runoff, percolation and evaporation describe how water moves through a wetland. This is the water cycle, not the removal of wastes.
- ✗ (b) Algae as the base of the food chain is a habitat and food-web function, closer to a 'nursery' role than to a kidney's cleaning role.
- ✗ (c) Sediment balance and soil stabilisation are physical, erosion-control functions. They do not purify water the way kidneys do.
Remember · Wetlands = kidneys of the landscape: they filter and purify water, with plants trapping heavy metals, pesticides and excess nutrients.
Sources
- Ramsar Convention on Wetlands, Wetlands: a sustainable solution for water purification and security (Internet Archive copy) ↗ “They are commonly referred to as the earth’s kidneys, because they function as filters, absorbing pesticides and chemicals and removing harmful waste from water.”
- US EPA, Economic Benefits of Wetlands ↗ “Plant roots and microorganisms on plant stems and in the soil absorb excess nutrients in the water from fertilizers, manure, leaking septic tanks and municipal sewage.”
- NIH National Library of Medicine (PMC), Screening the Capacity of 34 Wetland Plant Species to Remove Heavy Metals from Water ↗ “Wetland plant species are able to remove heavy metals from the surrounding environment, which can be utilized for purification of polluted waters.”
Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·