Environmental Science and Ecology

The Stockholm Conference on the Human Environment was held on June 5, 1972, and this date was designated as World Environment Day. The conference was a landmark UN event that established environmental protection as a global priority.

Articles 48A (Directive Principles) and 51A(g) (Fundamental Duties) of the Indian Constitution specifically address environmental protection. Article 48A directs the state to protect and improve environment, while 51A(g) makes it a fundamental duty of citizens.

The passenger pigeon (Ectopistes migratorius) was once the most abundant bird in North America, with flocks containing billions of birds. Extensive hunting and habitat destruction led to their extinction, with the last known individual dying in Cincinnati Zoo in 1914.

Wind erosion occurs when vegetation cover is removed, exposing soil to wind. In arid and semi-arid regions, overgrazing by livestock is the primary cause as it destroys the protective vegetation layer, allowing wind to pick up and transport soil particles. While deforestation and land clearing also contribute, overgrazing is most severe in these fragile ecosystems.

Maharashtra became the first Indian state to implement environmental education as a compulsory separate subject in schools. This pioneering move in the mid-1990s set a precedent for other states to follow, recognizing the importance of environmental awareness from an early age.

Methane (CH4) is produced in anaerobic conditions by methanogens - in landfills, wetlands (marshes/bogs), rice paddies, and by ruminant animals through enteric fermentation. While its GWP is now estimated at 28-36 over 100 years, earlier IPCC reports used 21, making it the correct answer given the question's context.

The Green Revolution's high-yielding varieties required massive inputs: chemical fertilizers to support rapid growth, extensive groundwater extraction for irrigation, and heavy pesticide application to protect monocultures. All three imposed significant environmental costs including soil degradation, water depletion, and ecological disruption from chemical runoff.

Leguminous plants host nitrogen-fixing bacteria (like Rhizobium, not Nitrosomonas which are nitrifying bacteria) in root nodules that convert atmospheric N2 into ammonia. When legumes are multiple-cropped, they naturally replenish soil nitrogen, significantly reducing the need for synthetic nitrogen fertilizers. Note: the question incorrectly names Nitrosomonas, but the concept remains correct.

The Chernobyl disaster in April 1986 at the Chernobyl Nuclear Power Plant in Ukraine (then part of the Soviet Union) was the world's worst nuclear accident. The explosion and fire released large amounts of radioactive materials, killing 31 workers immediately, causing acute radiation sickness in 129 others, and leading to thousands of premature deaths from long-term exposure.

Mercury is a toxic heavy metal found in fluorescent tubes and certain batteries. When these items break in waste streams, mercury vapor or liquid can be inhaled or absorbed, leading to severe neurological and kidney damage. Copper and Cadmium do not share this specific profile in fluorescent bulbs.