1. Compare the formation of six features that are pro-
duced by shoreline erosion.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate