Which is a force is responsible for seafloor spreading? a. convection in the crust b. convection in the mantle c. the effect of tides d. condensation in the mantle

Which is a force is responsible for seafloor spreading?

D. condensation in the mantle

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.