Which if te following statements about stars is true? a. stars rarely differ in size b. none of these c. al stars are the same size d. stars vary greatly in size

The correct answer is D. Stars very pretty greatly in size. Have a great day :)

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.