What is a system?
A system is a something that needs not be consciously controlled or supervised, something natural. For example the ecosystem, where organisms can live and adapt to their surroundings without external help.
In a system, everything is important and should be considered. A system can affect anything outside of it or other systems as well. It makes our world, and must be sustained.
How humans and the environment are dependent on each other.
Humans all need what the environment has to offer to live on. Oil, water, animals and even the air. When the condition of the environment deteriorates, humans will suffer the consequences. However, these consequences are that of their own actions. The condition of the environment largely depends on humans, even though humans need a good environment for survival. When there is pollution, most likely than anything, it is done by humans, for industrialization.
Humans have the power to improve, conserve or destroy their environment. The mangrove that we visited is a great example of humans conserving and making an effort to improve the environment. Without the humans, natural causes can still destroy the environment and we can save it. Without what the environment has to offer, living will be a futile struggle for humans.