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Q53 (IAS/2022) Environment & Ecology › Ecology & Ecosystem Basics › Wetland ecosystems Official Key

"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?

Result
Your answer: —  ·  Correct: D
Explanation

The correct answer is Option 4. The analogy compares wetlands to kidneys because of their natural filtration and purification capabilities.

Just as biological kidneys filter waste and toxins from the bloodstream, wetlands act as huge biological filters for ecosystems. This function is primarily driven by aquatic plants (hydrophytes) and microorganisms that:

  • Absorb heavy metals: Plants like water hyacinths can sequester toxic pollutants.
  • Remove excess nutrients: They trap nitrogen and phosphorus from agricultural runoff, preventing eutrophication in larger water bodies.
  • Break down organic waste: Microbes in the wetland soil decompose organic matter, effectively "cleaning" the water.

While Options 1, 2, and 3 describe essential ecological functions (hydrology, food webs, and erosion control), they do not specifically address the purification/filtration aspect implied by the "kidney" metaphor. Option 4 directly explains how wetlands chemically and biologically cleanse the environment, making it the most accurate reflection of the statement.

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Q. "If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys." Which one of the followin…
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10
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This is a classic 'Functional Analogy' question found in the intro chapters of Shankar IAS or Majid Hussain. The strategy is simple: Don't just memorize definitions; map ecosystem functions to biological organs (Lungs = Gas Exchange, Kidneys = Filtration/Detox). If you missed this, you ignored the 'Ecosystem Services' table in your standard text.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Do wetlands' water cycles involve surface runoff, subsoil percolation, and evaporation?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > hydrological cyclE. > p. 24
Presence: 5/5
“Te hydrological cycle is an intricate combination of evaporation, transpiration, air-mass movements, condensation, precipitation, run of, percolation, and groundwater movements. Te greater part of atmospheric moisture, which eventually falls to the Earth as precipitation (rains), comes from the oceans. Some water takes a short cut in the water cycle and enters air (atmosphere) directly through evaporation and transpiration (from soil and vegetation) without returning to the oceans. Te process of evaporation, condensation and precipitation are essentially climatic and their functions in the water cycle would be quite simple if it were not for the constant motion in the atmosphere. Tis requires heat as well as moisture.”
Why this source?
  • Explicitly lists evaporation, runoff and percolation as constituent processes of the hydrological cycle.
  • Frames these processes as part of water movement on and in the Earth's surface, which applies to standing waterbodies.
Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > Fig. 7.9: Water cycle > p. 98
Presence: 5/5
“The continuous movement of water — upward as water vapour and downward through precipitation, passing through soil, rocks, and plants, and fi nally returning to water bodies, is called water cycle (Fig. 7.9). Thus, the water cycle helps in redistributing and replenishing water in rivers, lakes, and oceans. It also serves to conserve the total amount of water on the Earth. Rainwater that falls on the surface of the Earth, fl ows into ponds, lakes, rivers, and oceans or seeps into the ground.”
Why this source?
  • Describes rainwater flowing into ponds and lakes or seeping into the ground and returning to the atmosphere as vapour.
  • Directly links surface inflow, subsurface seepage and evaporation for small waterbodies analogous to wetlands.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Wetland Ecosystem > p. 27
Presence: 4/5
“Land areas of poor surface drainage, such as marshes and swamps are known as wetlands. Te wetland ecosystems experience periodic fooding from the adjacent deepwater habitat, and therefore supports plants and animals specifcally adapted to such shallow fooding or water logging. Wetlands are shallow lakes, generally less than three meters in depth. Wetlands include lake littorals (marginal areas between the highest and the lowest water level of the lakes), foodplains, bogs, fens, peat-land, marshy and swampy areas.”
Why this source?
  • Defines wetlands as shallow lakes and areas of poor surface drainage subject to periodic flooding and waterlogging.
  • Identifies wetlands as shallow waterbodies where hydrological processes (surface flow, percolation and evaporation) will operate.
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SIMILAR QUESTIONS

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