Question

Flow of energy declines as it passes from food chain explained by

• A. First law of thermodynamics
  
• B. Newton’s third law
  
• C. Newton’s second law
  
• D. Second law of thermodynamics
  

Answer 1

The correct option is D Second law of thermodynamics


Flow of energy in a food chain :

• The sequence of the energy flow in the ecosystem is studied in the form of a food chain with various trophic levels (nutritional status) and is as follows:-
• Producers (plant) → Primary consumers → Secondary consumers
• Features of the energy flow
• The energy flow decreases as we go up the trophic levels due to the 10% law. The law states that only 10% of the energy is transferred to each trophic level as we go up the trophic levels.
• Hence, the number of trophic levels is limited.
• The energy flow is unidirectional
• The flow of energy is represented by the rate of biomass production. (Primary productivity in case of producers and secondary productivity in case of consumers)

Flow of energy and the first law of thermodynamics :
The first law of thermodynamics states that energy cannot be created nor destroyed; it can only be converted from one form to another. In case of the energy flow in the food chain, energy is transferred as chemical energy from producers to consumers in a unidirectional manner. The energy that is lost in each transfer is converted to heat energy. Therefore the total energy in the ecosystem remains constant.

Flow of energy and the second law of thermodynamics :
In the food chain, according to the 10% rule, only 10% of energy is transferred to each trophic level. The rest of energy is lost as heat due to the process of respiration increasing the entropy of the system.