Question

which statements about diffusion are accurate? select all that apply.

molecules do not move unless they are in an area with a concentration gradient.

diffusion across a cell membrane may occur through protein transporters.

diffusion requires an input of energy to drive the movement of molecules.

net movement of molecules is from areas of high concentration to areas of low concentration.

gas molecules can diffuse freely through cell membranes.

Explanation:

• Molecules are in constant motion due to kinetic energy, regardless of concentration gradient. So the statement "Molecules do not move unless they are in an area with a concentration gradient" is incorrect.
• Diffusion across a cell membrane can occur through protein transporters (facilitated diffusion). This statement is correct.
• Diffusion is a passive process and does not require an input of energy. So the statement "Diffusion requires an input of energy to drive the movement of molecules" is incorrect.
• Net movement of molecules in diffusion is from areas of high concentration to areas of low concentration. This statement is correct.
• Gas molecules (e.g., \(O_2\), \(CO_2\)) can diffuse freely through cell membranes as they are small and non - polar. This statement is correct.

Answer:

• B. Diffusion across a cell membrane may occur through protein transporters.
• D. Net movement of molecules is from areas of high concentration to areas of low concentration.
• E. Gas molecules can diffuse freely through cell membranes.