Describe one example of when an ecosystem can become unstable. be sure to describe both the biotic and abiotic factors in your example for full credit

An ecosystem becomes unstable when there is an unequal number or ratio of predators and preys. Predators are animals that consume smaller animals and other edible produces found within the environment, while preys are first consumers of the producers (i.e. plants) that are found around a particular area. 

When there is a greater number of predator over prey, the result is a decrease in population of primary consumers and the environment will also follow by increasing its plant growth, and other processes. When there is a great number of prey over predator, producers will have a hard time to thrive providing less efficiency in producing supply for animals that are dependent for food, water, and shelter. 

The Yellowstone National Park is a very good example of this predator-prey relationship. The re-introduction of the wolves made the ecosystem become balanced once again.

That would be exocytosis