RAS question
Consider the following statements about Mangrove forests: 1. Mangroves grow in the intertidal zones of tropical and subtropical coastlines. 2. Pneumatophores are aerial roots that help mangroves breathe in waterlogged, oxygen-deficient soils. 3. The Sundarbans, shared between India and Bangladesh, is the world's largest mangrove forest. 4. Mangroves are effective carbon sinks, storing up to 4 times more carbon per unit area than tropical rainforests. Which of the following is correct?
Correct answer: (D) 1, 2, 3 and 4.
All four statements are correct: mangroves grow in tropical and subtropical intertidal coasts, use pneumatophores to breathe in oxygen-poor soils, include the Sundarbans as the world's largest mangrove forest, and act as high-capacity blue-carbon sinks.
Explanation
Mangroves are coastal trees and shrubs adapted to the intertidal belt: they live between land and sea, where daily tides, salt water and waterlogged soil make ordinary plant growth difficult. Their roots explain much of this success. Aerial roots with lenticels, including finger-like pneumatophores, take in air when the mud has little oxygen. The Sundarbans, shared by India and Bangladesh, is the world's largest mangrove forest. The carbon statement is also correct: mangroves are blue-carbon ecosystems that can store three to five times more carbon per unit area than tropical rainforests, because anaerobic waterlogged soils preserve organic matter.
Why the other options are wrong
- (A) Option A drops statement 4, although mangroves are correctly described as blue-carbon ecosystems with far higher carbon storage per unit area than tropical rainforests.
- (B) Option B keeps the habitat and pneumatophore statements but wrongly excludes the Sundarbans statement and the blue-carbon statement, both of which are correct.
- (C) Option C omits statement 1, even though mangroves are specifically associated with tropical and subtropical coastal intertidal zones.
Concept
This tests coastal ecosystems under World Geography, especially mangrove habitat, root adaptations, the Sundarbans and blue carbon. RAS repeats such themes because they connect physical geography with environment, biodiversity and climate-change mitigation.