"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?
AThe water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.
BAlgae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.
CWetlands play a vital role in maintaining sedimentation balance and soil stabilization.
DAquatic plants absorb heavy metals and excess nutrients.
Answer & Solution
Correct answer: D. Aquatic plants absorb heavy metals and excess nutrients.
Answer: D. The 'kidneys of Earth' analogy reflects wetlands' role in absorbing heavy metals and excess nutrients (water purification function).
The kidney analogy is about FILTRATION AND DETOXIFICATION. Just as kidneys filter blood and remove toxins/excess salts from the human body, wetlands FILTER WATER passing through them, removing pollutants, sediments, heavy metals, excess nutrients (nitrogen, phosphorus from agricultural runoff), and toxins.
Specifically:
- AQUATIC PLANTS (cattails, hyacinth, reeds, mangroves) ABSORB HEAVY METALS like cadmium, lead, mercury into their tissues (phytoremediation).
- Microbial communities in wetland sediments BREAK DOWN organic pollutants.
- Plants ABSORB EXCESS NITROGEN AND PHOSPHORUS from runoff, preventing eutrophication of downstream water bodies.
Distractors:
(A) Water cycle is broader; not specifically the kidney analogy.
(B) Food chain support is the 'lungs/ecosystem' angle.
(C) Sediment balance is important but not the kidney/filtration metaphor.
Option D directly captures the filtration/detoxification analogy.
Source: Ramsar Convention / NCERT Class 12 Biology Ch 14 (Ecosystem).
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