Suppose you want to perform a scientific investigation to find out how high a ball bounces on diferent kinds of surfaces. What are appropriate materials to reference before beginning your investigation? What are examples of
appropriate reference materiais?

answer; /// i believe the name your looking for is called (plaque)or check good luck

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.