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

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

For the strategies below, decide whether they are best described as demand-side solutions or supply-side solutions to meeting human needs for fresh water. remember that a demand-side solution reduces demand for fresh water, whereas a supply-side solution increases the supply of fresh water. (a) damming a river to create a reservoir (b) desalinating seawater (c) a nation invading a neighboring country to access their rivers (d) raising water prices for consumers and businesses (e) providing tax breaks for companies that use less water (f) replacing inefficient irrigation with more-efficient drip irrigation to grow crops (g) requiring low-flow showerheads in all new homes

How do all types of diffusion/passive transport actually ‘work’ without using even the smallest amount of cellular energy?