1. How do diffusion and facilitated diffusion differ? Diffusion favors one containment space over the other.
Diffusion does not require that the molecule be small enough to pass through the membrane.
Facilitated diffusion is affected by the concentration levels.
Facilitated diffusion requires the molecule to receive help to cross the cell membrane.

2. What does active transport require, and why does the process require it?
sodium and potassium; to pump out concentrated molecules
sodium; to replace the pumped out potassium
protein; to mark molecules that need to be forced out
energy; to move molecules against the concentration gradient