What is the main difference in the movement of molecules during simple diffusion and facilitated diffusion? Facilitated diffusion uses protein channels. Simple diffusion moves large molecules. Facilitated diffusion moves all molecules.

Answer 1

The main difference in the movement of molecules during simple diffusion and facilitated diffusion lies primarily in the mechanisms of transport and the types of molecules involved.

1. Simple Diffusion:

   • In simple diffusion, molecules move directly through the phospholipid bilayer of the cell membrane down their concentration gradient (from an area of higher concentration to an area of lower concentration) without the need for energy or assistance from proteins.
   • This process is typically used by small, nonpolar molecules (e.g., oxygen, carbon dioxide) that can easily pass through the lipid bilayer.

2. Facilitated Diffusion:

   • Facilitated diffusion, on the other hand, involves specific protein channels or carriers embedded in the cell membrane that help transport molecules across the membrane. This process also moves molecules down their concentration gradient, but it is primarily used for larger, polar, or charged molecules (e.g., glucose, ions) that cannot easily cross the lipid bilayer on their own.
   • While facilitated diffusion does not require energy (it is also a passive transport mechanism), it does rely on membrane proteins to facilitate the movement of certain substances.

In summary, simple diffusion does not involve proteins and typically moves small, nonpolar molecules, whereas facilitated diffusion uses protein channels to transport larger, polar, or charged molecules across the membrane.

Answer 2

pick one of the provided answers

Answer 3

The correct choice is: Facilitated diffusion uses protein channels.

This highlights a key distinction: simple diffusion involves the direct movement of molecules through the membrane, while facilitated diffusion relies on protein channels or carriers to help transport larger or polar molecules.