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Biology · 2023 · 2 marks
CBSE 2023 · Region 1 · Set 2 · Q20
Plants capture only 2-10 percent of the photosynthetically active radiation of the Sun and this small amount of energy is able to sustain the entire…
Plants capture only $\displaystyle 2$-$\displaystyle 10$ percent of the photosynthetically active radiation of the Sun and this small amount of energy is able to sustain the entire living world. During this process, ecosystems are in consonance with the two laws of thermodynamics. Explain.
Marking-scheme solution
First law of thermodynamics - All organisms are dependent for their food on producers (who capture PAR) either directly or indirectly, unidirectional flow of energy from sun to the producers and then to consumers.
Second law - Organisms need a constant supply of energy to synthesize the molecule they require, to counteract the universal tendency towards increasing disorderliness.
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