Question

Zebra eats grass lion eats zebra what is this an example of?

Answer 1

This is a an example of the food chain. The zebra is a Herbivore and eats grass and the Lion is a carnivore who eats meat aka as the poor zebra D;

Answer 2

Ecosystem; a cycle 
More accurately the Food Chain
For the Zebra feeds on grass that also feeds on smaller organisms to live; The Zebra is a herbivore (Eats only plants) while the lion is a carnivore (Only eats meat) it is placed higher on the food chain, making Zebra's underneath of the Lion's 
Lion-> Zebra-> Grass