The center of a tornado is characterized by its
a) very high pressure
b) eye wall
c) sinking air

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.

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .