The correct option is 10 %.
Explanation
Energy flow in an ecosystem is unidirectional and governed by the laws of thermodynamics. The quantitative transfer of energy from one trophic level to another is described by the efficiency of ecological productivity.
Analysis of Energy Transfer
The specific principle governing this transfer is known as Lindeman’s 10 % Law, proposed by Raymond Lindeman in 1942.
- The Rule: It states that during the transfer of organic food energy from one trophic level to the next higher level, only about 10 % of the energy is stored as biomass (flesh) and becomes available to the next consumer.
- Energy Loss: The remaining 90 % of the energy is lost to the environment. This loss occurs primarily through respiration (heat loss), metabolic activities (movement, digestion), and unassimilated waste.
- Consequence: Due to this significant loss at each step, the amount of available energy decreases rapidly as one moves up the trophic levels. This explains why food chains rarely exceed four or five levels and why the Pyramid of Energy is always upright.
Key Takeaway
Lindeman's 10% Law establishes that energy transfer between trophic levels is highly inefficient, with approximately 90% of energy lost as heat and metabolic cost at each step.