Sound waves travel the fastest through

Sound travels fastest through the SOLIDS

Explanation:

Since the density of solids is high and the molecules of a solid are closely packed, sound waves are quickly transmitted from one molecule to the next thus enabling it to travel faster. The speed of sound, therefore, is fastest in solids, followed by liquids (less dense than solids) and then gas (least dense).

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.