Question

while water molecules are polar, they are also very small. one fact not mentioned in the video is that some (but not most) water molecules are able to squeeze directly through the phospholipid bilayer due to their small size. this is an example of which of the following? simple diffusion active transport facilitated diffusion

Explanation:

Simple diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration without the help of transport proteins. Small non - polar or some small polar molecules like water can pass directly through the phospholipid bilayer by simple diffusion. Active transport requires energy and uses transport proteins to move molecules against their concentration gradient. Facilitated diffusion uses transport proteins (channels or carriers) to move molecules across the membrane. Since water molecules are moving directly through the bilayer due to their small size without the help of transport proteins, it is simple diffusion.

Answer:

simple diffusion