What happens to the atoms in a scoop of ice cream as it melts? a. they decrease in temperature. b.they lose energy. c.they vibrate faster. d.they are held tightly in a fixed position.

It is C.They vibrate faster

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.