”The energy flow in the ecosystem follows the second law of thermodynamics.” Explain. 

Explanation

Second law of thermodynamics , also called law of Entropy , states that energy transfer or energy transformation is never cent per cent . It involves degradation or dissipation from as is used to maintain the metabolism , So only a part of energy is stored in the biomass .
When a producer traps radiant energy for photosynthesis , only 2-10 per cent of PAR (and only 1 to 5 per cent of incident solar radiation ) is used in photosynthesis called GPP. About 0.2 to 1 % of incident radiation is used by plants in respiration while 0.8 to 4 % of incident radiations is used to produce biomass called NPP .
When a herbivore eats a producer , then about 90% of potential energy is dissipated while only 10% of energy is available for producing biomass. The same will be repeated when a herbivore is eaten by a carnivore .