Trophic level is the specific place occupied by an organism in a food chain on the basis of its source of nutrition or food. Primary producers (green plants) belong to the first trophic level, they prepare the food by photosynthesis by utilising radiant energy of sun. Plant eating herbivores (e.g., cow, grasshopper) are primary consumers and occupy second trophic level. Secondary consumers are carnivores (e.g., frogs, lizards) which feed on herbivores and occupy third trophic level in a food chain. Tertiary consumers or top carnivores (e.g., lion, man) feeding on secondary consumers are present at next higher trophic level.