Ecological pyramids typically represent a simplified view of energy flow or biomass within an ecosystem. The limitations of ecological pyramids include:
No place for saprophytes: Saprophytes (decomposers) play a crucial role in nutrient cycling but are often not explicitly represented in ecological pyramids.
Simplified food chains: Ecological pyramids often depict simple, linear food chains, while in reality, ecosystems have complex food webs.
Ignoring same species at multiple trophic levels: Some species can occupy multiple trophic levels (e.g., an omnivore). Ecological pyramids often don’t account for this.
The statement “It accommodates a food web” is not a limitation; it would be an improvement if they did.
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Ecosystem
A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is : 
AB is a part of an electrical circuit (see figure). The potential difference \(V_A - V_B\), at the instant when current \(i = 2\) A and is increasing at a rate of 1 amp/second is:
Three identical heat conducting rods are connected in series as shown in the figure. The rods on the sides have thermal conductivity 2K while that in the middle has thermal conductivity K. The left end of the combination is maintained at temperature 3T and the right end at T. The rods are thermally insulated from outside. In steady state, temperature at the left junction is \(T_1\) and that at the right junction is \(T_2\). The ratio \(T_1 / T_2\) is 