Unlike secondary succession, primary succession a. occurs in an area where existing communities still exist. b. has the challenge of occuring in areas where no community exists at all. c. proceeds at a much faster rate. d. leads to an increased number of different species over time.

How many chromosomes does each human cell contain? a. 23 chromosomes b. 26 chromosomes c. 43 chromosomes d. 46 chromosomes

Why is earth's outer core hotter than earth’s oceanic crust? earth’s oceanic crust is denser than earth’s outer core is. earth’s oceanic crust has lava flowing from the mantle. earth’s outer core has a composition of solid iron and nickel. earth’s outer core is deeper within earth than oceanic crust is.

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic