Question

Check all that apply: The ecological efficiency in a food chain is usually less that 100% because:

  

some material is not eaten

   

material eaten in son converted with 100% efficiency

   

of the addition of more than 2 trophic levels

   

the decrease in primary productivity

Answer 1

The ecological efficiency in a food chain is usually less that 100% because:

the decrease in primary productivity

Explanation

Ecological efficiency is the efficiency by which transfer of energy occurs from one trophic level to the next trophic level in a food chain.

The ecological efficiency could not be 100 %. To understand the reason of inefficient ecological efficiency, we should be familiar with the few basic terminology such as primary productivity, gross primary productivity and net primary productivity.

Basically, the autotrophs fix the energy from sunlight into the chemical energy through the process of photosynthesis. The total amount of energy fixed by the autotroph through the process of photosynthesis is referred as gross primary productivity of that particular autotroph. Then the organisms utilises fraction of that energy (gross primary productivity) for the completion of respiration. Total energy remains after the respiration is referred as net primary productivity.

It is interesting to note that, net primary productivity at a particular trophic level is only 10 % of the net primary productivity of the proceeding trophic level. Main reason for the decrease in net primary productivity are predatory death, egestion and cellular respiration. These factors leads to the reduction in the amount of energy transferred at each trophic level.

In conclusion, we can say that the ecological efficiency is less than 100 % because of the decrease in primary productivity at each trophic level.