Q. “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?

Explanation : 

Importance of Wetlands in Environmental Health

The statement “If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys” is an analogy that compares the role of wetlands in the environment to the role of kidneys in the human body. Just as kidneys filter and remove waste products and excess substances from the bloodstream, thus helping to maintain the body’s internal environment, wetlands perform a similar function for the Earth’s water systems.

Wetlands as Earth’s Natural Filters

The correct answer, “Aquatic plants absorb heavy metals and excess nutrients,” best reflects the analogy because it describes how wetlands act as natural filters for the environment. Here’s a breakdown of how this function is similar to that of kidneys:

• Filtering Waste: Wetlands filter out pollutants from the water, including heavy metals and excess nutrients, much like kidneys filter out waste products from the blood.
• Maintaining Balance: Just as kidneys help to regulate the balance of electrolytes and other substances in the body, wetlands help to maintain the chemical balance of water ecosystems by absorbing and transforming excess nutrients that could otherwise lead to problems like eutrophication, which is the over-enrichment of water bodies with nutrients, leading to excessive growth of algae and depletion of oxygen.
• Detoxification: Wetlands can break down or store harmful pollutants, similar to how kidneys detoxify the blood by removing toxins and converting them into less harmful substances that can be excreted.

The other options, while they describe important functions of wetlands, do not directly relate to the analogy of wetlands being the Earth’s “kidneys“:

• The water cycle in wetlands is more akin to the circulation of fluids in the body rather than the specific filtering function of kidneys.
• Algae forming the nutrient base for other organisms is related to the food chain and productivity of the ecosystem, not to the filtering and regulatory role of kidneys.
• Maintaining sedimentation balance and soil stabilization is more about physical support and erosion control than the specific cleansing and filtering function that the kidneys perform.

Therefore, the function of aquatic plants absorbing heavy metals and excess nutrients is the one that best reflects the idea of wetlands functioning as the Earth’s kidneys, providing a vital cleansing and balancing role in the environment.