Walking through the woods, you come upon a patch of ferns. you notice small, scabby-looking brown dots on the underside of the fronds. what are they, and what is their function?

that scientist would be robert hooke

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.