What did not contribute to the expansion of Marine Science? a. Improvement of design of research equipment
b. War and conflict
c. The Catholic church during the middle (dark) ages
d. Shipbuilding improvements including the use of iron and the steam engir

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.

sorry to break it to ya but no one can answer your question it's just

jk but i am serious about the part that most people cant answer it beacuse you did not mention the section you are talking about. but it would if you added some detail and were a bit more specific.