What is the definition of ecosystem in geography?
With Example and detailed

The vegetation that thrives in the tundra is limited to a. mosses, barley, wheat, and corn. b. coniferous trees. c. dwarf shrubs, mosses, lichen, potatoes, and beans. d. mosses, lichen, algae, and dwarf shrubs.

Many areas surrounding the caspian sea contain important a. rare minerals b. forestry resources c. gold and silver mines d. oil and natural gas fields

If the diameter of the sphere is 12 cm, what is the surface area?