What is the main factor that restricts the number of trophic levels in the grazing food chain?

Transfer of energy following the 10% law

The correct answer is Option (2)- Transfer of energy following the 10% law.

The transfer of energy following the 10% law is the main factor that restricts the number of trophic levels in the grazing food chain. The 10% law states that approximately only 10% of the energy available at one trophic level is transferred to the next trophic level.

As energy flows through a food chain, each trophic level utilizes a portion of the energy for its own metabolic needs and loses some energy as heat during processes like respiration. Consequently, only a fraction of the energy is passed on to the next trophic level. This energy loss limits the amount of energy available to support higher trophic levels.

With each successive trophic level, there is a further reduction in the available energy. This decrease in energy transfer makes it inefficient to sustain a large number of trophic levels in a food chain. As a result, the number of trophic levels in a grazing food chain is typically limited.

For example, let's consider a simple grazing food chain: grass (producer) → grasshopper (primary consumer) → mouse (secondary consumer) → snake (tertiary consumer). If the grass captures 1,000 units of energy from the sun through photosynthesis, approximately 10% (100 units) of that energy will be transferred to the grasshopper. Then, only around 10% (10 units) of the energy from the grasshopper will be available to the mouse, and so on.

As the energy decreases at each trophic level, it becomes increasingly challenging to sustain additional trophic levels in the food chain. This limitation is due to the inefficiency of energy transfer and the decreasing amount of available energy.

Therefore, the transfer of energy following the 10% law acts as a major constraint on the number of trophic levels in the grazing food chain. It helps shape the structure and dynamics of ecosystems by influencing the distribution and abundance of organisms at different trophic levels.