Q1 What is a system
It is a area that is able to sustain itself. But in this case the area is man made and took some time to be able to stabilise and sustain itself.
Q2 How humans and environment are dependent on each other.
Without the humans, the environment might have some problems getting dependent on each other. The humans help in stabilizing it by helping get rid of pest or weeds that would hinder the process of growing the plants. The plants help by giving the human resources to be able to maintain itself and have resources to help in the growth of plants. Thus they both benefit each other in stabilizing itself.