First Trophic Level:
1. The organisms of this trophic level are plants and are also called producers.
2. They transform solar energy into chemical energy by photosynthesis.
e.g. : grass (all green plants).
Third Trophic Level:
1. The organisms of this trophic level are animals and are also called secondary consumers.
2. They obtain chemical energy by eating other animals.
e.g. : all carnivores (like lion).