Scientists have difficulty predicting the frequency and intensity of flooding along major rivers, such as the Mississippi, because the increased run-off from impervious surfaces in large human settlements changes how much water flows into rivers.

Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.

In stage 2 farmers used the land primarily to grow food for their families and their small communities.

Which of the following insects is a decomposer? a. mosquito. b. caterpillar. c. beetle. d. none of the above.