Question

select the true statements.
once equilibrium is reached via facilitated diffusion, molecules keep moving.
charged molecules can only cross the cell membrane by active transport.
in facilitated diffusion, molecules move from areas of high concentration to areas of low concentration to reach equilibrium.
molecules can only cross the cell membrane directly through the phospholipids.

Explanation:

• Once equilibrium is reached via facilitated diffusion, molecules keep moving: In facilitated diffusion, equilibrium is a dynamic state. Molecules continue to move back and forth across the membrane at equal rates.
• Charged molecules can only cross the cell membrane by active transport: Charged molecules (ions) can also cross the membrane via facilitated diffusion through ion channels. So this statement is false.
• In facilitated diffusion, molecules move from areas of high concentration to areas of low concentration to reach equilibrium: Facilitated diffusion is a passive transport process. Molecules move down their concentration gradient (from high to low concentration) until equilibrium is achieved.
• Molecules can only cross the cell membrane directly through the phospholipids: Small non - polar molecules can cross directly through the phospholipid bilayer. However, many molecules (such as polar molecules, ions) cross via transport proteins (facilitated diffusion or active transport). So this statement is false.

Answer:

• Once equilibrium is reached via facilitated diffusion, molecules keep moving.
• In facilitated diffusion, molecules move from areas of high concentration to areas of low concentration to reach equilibrium.