Which statement is true about a cell? a. they can only reproduce by budding. b. they do not pass on genetic traits. c. all organisms are made up of one or more cells. d. they are unable to respond to their environment. c

answer; ///(statins)/aka as hmg coa

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.