Q.46 Which one of the following ecosystems is represented by an inverted pyramid of numbers?
(A) Grassland
(B) Pond
(C) Desert
(D) Parasitic forest

Correct Answer

The correct answer is (B) Pond. In a pond ecosystem, the pyramid of numbers is inverted because a small number of phytoplankton producers support a larger population of zooplankton and other consumers.​

Pyramid of Numbers Overview

A pyramid of numbers illustrates the count of organisms at each trophic level in an ecosystem. Upright pyramids show more producers at the base than consumers higher up, but inverted ones reverse this with fewer individuals at lower levels supporting more at higher levels.​

Pond ecosystems exemplify this inversion: microscopic phytoplankton are few but reproduce rapidly, sustaining vast numbers of zooplankton, which in turn feed fish and other organisms.​

Option Analysis

• (A) Grassland: Features an upright pyramid with abundant grasses as producers outnumbering herbivores and carnivores.​

• (B) Pond: Shows inversion due to fewer phytoplankton than primary consumers like zooplankton.​

• (C) Desert: Typically upright, as sparse producers like shrubs support even fewer herbivores adapted to harsh conditions.​

• (D) Parasitic forest: May exhibit partial inversion if one tree hosts numerous parasites, but standard classification favors ponds for clear examples; parasitic chains can invert, though not purely “forest.”​

Exam Preparation Tips

Grasping ecological pyramids aids in understanding energy flow and trophic dynamics. Focus on aquatic vs. terrestrial differences for questions on biomass or numbers pyramids.​