MPPSC 2023 Prelims Paper-I · Question 6 of 100

Correct — C, Marine ecosystem. Oceans are the largest and most continuous ecosystems on Earth, and water's high heat capacity gives them enormous thermal and chemical buffering — temperature, salinity and other conditions change far more slowly and gently there than on land. This buffering supports a long-established, minimally disturbed community, which is the classic definition of ecological stability.

• (a)Forest ecosystem — Forests are diverse and comparatively stable among land ecosystems, but they remain far more exposed to seasonal climate swings, fire and human disturbance than the buffered marine environment, so they rank below it in stability.
• (b)Desert ecosystem — Deserts see extreme temperature swings between day and night and scarce, unpredictable rainfall — among the least stable, most fluctuating ecosystems, not the most stable.
• (d)Grassland ecosystem — Grasslands are strongly shaped by seasonal rainfall, grazing and fire, making them comparatively more variable than the buffered marine environment.

Ecological stability describes how well an ecosystem resists and recovers from disturbance and fluctuation, not how productive or biodiverse it is. Large, ancient, buffered systems tend to be the most stable; small or climatically extreme systems tend to be the least. Among the major ecosystem types, the marine (ocean) ecosystem is considered the most stable because of its vast, continuous size and water's strong thermal buffering, which dampens the swings that disturb terrestrial ecosystems.

The trap is equating 'stable' with 'productive' or 'biodiverse' — a rainforest can be more productive and diverse yet still be more exposed to disturbance (seasonal change, fire, deforestation) than the vast, buffered ocean.

• The marine (ocean) ecosystem is considered the most stable of the major ecosystem types
• Stability here means resistance to environmental fluctuation, not productivity or diversity
• Deserts and grasslands are comparatively unstable owing to extreme or seasonal climate swings
• Water's high heat capacity gives oceans strong thermal buffering compared with land

• Equating 'stability' with 'high productivity/diversity' (tropical forests are highly productive but not the most stable)
• Assuming a forest, not the ocean, is automatically the most stable ecosystem

MPPSC/UPSC ecology MCQs often rank ecosystem types by a single property (stability, productivity, diversity) — expect direct 'which is the most X ecosystem' framing.

No directly related past PYQ was found.

• practice — not a real PYQ

  Which of the following ecosystems is generally considered the LEAST stable, owing to extreme temperature fluctuation and scarce, unpredictable rainfall?

  • (a)Marine ecosystem
  • (b)Desert ecosystem
  • (c)Forest ecosystem
  • (d)Freshwater ecosystem

  Answer(b) Desert ecosystem — extreme day-night temperature swings and erratic rainfall make it among the least stable ecosystems.

• practice — not a real PYQ

  The high ecological stability of the marine ecosystem, relative to terrestrial ecosystems, is chiefly attributed to:

  • (a)High species diversity alone
  • (b)Absence of any predators
  • (c)Its vast size and the ocean's strong thermal buffering
  • (d)Complete absence of seasonal change

  Answer(c) Its vast size and the ocean's strong thermal buffering — these dampen the fluctuations that destabilize smaller or terrestrial ecosystems.