What is the characterization of a cell membrane that controls which substance can enter and exit the cell?

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.

If a force of 40 newtons moves a cart a distance of 9 meters, the work done is nm. if the same force moves the same cart three times that distance, the work done is nm.

Through which structure do the sperm travel to exit the testes?