Why are there hundreds of different protein channels?
a. they work for different molecules
b. the cells make multiple protein channels just in case one dies
c. in case molecules have to go from a low to high concentration
d. smaller molecules will go through protein channels to save space

Which of the following may one conclude from a map that shows the average ph value of rainfall in the u.s.? acid rain is a more serious problem on the east coast. acid rain falls equivalently across the continental u.s. there are more factories on the west coast. the midwest has fewer forests than the rest of the u.s.