Suggest why an increasing number of megacities are located in lower income countries or newly emerging economies.

At which point on the diagram do convection currents occur to drive plate movement?

What evidence does the writer give to support his argument about coral reefs? a) he speaks of the activities of coral polyps. b) he describes the composition of the great barrier reef. c) he emphasizes the ways in which coral reefs are fragile. d) he points out the ways that scientists do research on the reefs.

What is the amount of organic matter in all living organisms in a habitat called?