Q.4 Explain Flow of Energy in an Ecosystem.
Answer:
In an ecosystem, energy as well as materials travels from one trophic level to the next.
Trophic Level
Trophic level is the level at which an organism feeds in food chain. The first trophic level is made of producers; the second of primary consumers and so on.
Flow of Energy
The flow of energy in different trophic levels of ecosystem is unidirectional. The following is an overview of the flow of energy in an ecosystem.

Source of Energy in an Ecosystem
The Sun is the primary source of energy for all ecosystems. Producers get solar energy and transform it into chemical energy by the process of photosynthesis. They store this energy in their tissues and also transform it into mechanical and heat energy during their metabolic activities.
Movement of Energy
The energy in producers’ tissues flows to herbivores when producers are eaten. Herbivores transform it into mechanical and heat energy during their metabolic activities and store the rest in their tissues. Carnivores eat herbivores and get energy. They also use it for their body activities and store the rest in their tissues. After the death of producers and consumers, the energy stored in their tissues is used by the decomposers.
Storage and Expenditure of Energy.
The storage and expenditure of energy in an ecosystem is in accordance with the basic law of thermodynamics i.e. “energy can neither be created nor destroyed but can be transformed from one form into another”. In an ecosystem there is,
• Constant flow of energy from the Sun through producers to consumers and decomposers.
• A significant decrease in useful energy during transfer of energy at each trophic level.