UPSC Prelims 2022 · Question 43 of 98

UPSC Prelims 2022 question on Wetlands Kidneys of Earth

"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?

  1. The water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.
  2. Algae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.
  3. Wetlands play a vital role in maintaining sedimentation balance and soil stabilization.
  4. Aquatic plants absorb heavy metals and excess nutrients.
Show answer

Answer: D. Aquatic plants absorb heavy metals and excess nutrients.

Verdict

Correct answer: Option (d).

Analysis

The statement compares wetlands to kidneys of the Earth. The kidney's primary function is filtration — removing waste products and toxins from the blood.

Tropical rainforests are often called the 'lungs of the planet' because they generally draw in carbon dioxide and breathe out oxygen. Natural wetlands have often been referred to as 'earth's kidneys' because of their high and long-term capacity to filter pollutants from the water that flows through them.

Aquatic plants can uptake large amounts of metals from water and/or sediment through active and passive absorption, with this absorption capacity of metals through different organs such as roots, stems, and leaves, making these plants suitable for heavy metal alterations in the aquatic environment.

This filtration/purification function — absorbing heavy metals and excess nutrients — best reflects the 'kidney' analogy.

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