Comprehension:
An ecosystem is a structural and functional unit of nature, which comprises of both abiotic (e.g., air, water, soil) and biotic (e.g., producers, consumers, decomposers) components. Productivity, decomposition, energy flow and nutrient cycling are four key important processes in an ecosystem. Primary productivity is rate of capture of solar energy or biomass production by producers. The energy flow is unidirectional and plants can utilize only 1% of available solar energy and energy is transferred among trophic level, following 10% law. The rate of capture of solar energy or total production of biomass by producers is called as gross primary productivity. The energy left after utilisation by producers is called as net primary productivity. Rate of assimilation of food energy by the consumers is referred as secondary productivity. Decomposition processes such as fragmentation of detritus, leaching and catabolism are responsible for converting detritus into CO2, H2O and inorganic nutrients.
What will be the energy available at secondary consumer level, if total available solar energy is 106 J ?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 100 J
The passage gives two rules. Plants capture only 1% of the available solar energy, so the producers hold 106 × 0.01 = 104 J. Thereafter the 10% law applies at each transfer.
Primary consumers therefore receive 104 × 0.1 = 103 J, and secondary consumers receive 103 × 0.1 = 102 J, that is 100 J.