Wetlands have important filtering capabilities. Wetlands filter surface water from higher dry land before it reaches open water. As the runoff water passes through, the wetlands retain excess nutrients and some pollutants. This filtering also helps reduce sediment that would clog waterways and affect fish and amphibian egg development. In performing this filtering function, wetlands save us a great deal of money. Without the natural filtration system of a wetland, money would most likely be spent on
(A) building barrier islands
(B) coastal rebuilding efforts
(C) waste water treatment plants
(D) non-point source clean-up

According the inverse square law, doubling the distance from the source of the sound, a speaker, for example, will drop the sound 6 db each time. if you were standing in the back of an auditorium, 32 feet away from a speaker not using any amplification, would you be able to hear a speaker clearly? why or why not?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.

What materials must dams have to produce electricity, and what must occur?