9. describe the position of the vein(s) in each model. a. describe model 1.
b. describe model 2.

i think that the best answer would be c.

tell me if im wrong : )

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.