With respect to air, water, and material resources, which of the following is true?
A) A forest is a closed system.
B) A forest is an open system.
C) A forest is an open system in terms of air, but closed in terms of material resources.
D) A forest is an open system in terms of water, but closed in terms of energy resources.
Question 2
In terms of matter and resources, the Earth is essentially a(n) ________ system; In terms of energy, the Earth is a(n) ________ system.
A) closed; closed
B) closed; open
C) open; open
D) open; closed