Trophic Levels : The various steps in a food chain at which the transfer of food (or energy) takes place are called trophic levels. Example A food chain operating in a grassland is given below :
Grass -> Insects -> Frog-> Birds
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In this food chain
1. Grass represents first trophic level.
2 Grasshopper represents second trophic level.
3. Frog represents third trophic level.
4 Eagle represents fourth tropic level.