The lecture you were listening to is over. The bell that rang in the hall signaled the end of class. You get up out of your seat, pick up your things and walk out the classroom door. Which kind of nerves sent the signals from your brain to initiate your physical movements

the sun d the answer is sun

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.

i would think a oil tanker that has leaked in a bay